Journal articles on the topic 'Industries de pointe – Tunisie'

RésuméUne méthodologie a été proposée pour la prédétermination des débits à partir de la pluviométrie. Il s’agit d’associer, en entrée, les simulations Monte Carlo de hyétogrammes de pluie nette avec un modèle d’hydrogramme unitaire à base de géomorphologie pour obtenir des hydrogrammes simulés en sortie. À la fin des simulations, l’analyse statistique des sorties permet d’apprécier l’étendue de la variabilité de la réponse du bassin aux événements pluvieux et de caractériser les débits et les temps de pointe. Un total de 44 simulations ont été menées pour chacun des 15 événements observés pour un petit bassin versant situé en Tunisie centrale. L’analyse des hydrogrammes générés a montré une assez faible dispersion des débits de pointe, d’une simulation à l’autre, pour un événement donné, et a mis en évidence la dissymétrie des distributions des débits et temps de pointe. L’exploitation des résultats de l’ensemble des simulations permet de dégager des relations empiriques caractérisant le comportement du bassin selon les débits de pointe, les temps de pointe, les temps de base et les volumes écoulés.

Addressing the Social Determinants of Health is critical if we truly want to achieve health equity. The World Health Organization’s Commission on the Social Determinants of Health (2008) recognized the need to broaden the understanding of these determinants among the general public to facilitate change in communities and improve the overall health status. Using the data from the Tunisian Health Examination Survey (2016), this quantitative preliminary study explored the state of social inequity in health among the Tunisian population using a quantitative statistical analysis that shed light on the relations between the SDHs (Age – gender – SES – Geographical location – Area of residence – and Educational attainment) and the self-rated health status. This preliminary study explored the current state of health equity in Tunisia through exploring the hidden patterns of social identity formation and power relation inside society. This preliminary study also pointed out certain aspects of health inequity in Tunisia as well as the social factors and determinants contributing to the status-quo. The findings of this preliminary study could be the basis of an ambitious academic work that will explore the intersection between SDHs and their impact on health outcomes in Tunisia that will be an asset in the process of implementing health equity policies in the future.

Purpose Extending the service business in manufacturing firms has received significant attention in recent research. As it has been acknowledged by many authors, developing a service orientation can offer additional benefit potential. However, achieving profit with a competitive strategy depends on the firm’s characteristics and equally on environmental ones. In this scope, the present paper aims to identify antecedents to service orientation and the impact of this strategy on the firm’s performance. Design/methodology/approach The authors first conducted a qualitative research to identify the different forms used to serve clients. Then to test the hypotheses, the authors conducted a quantitative study on a sample of 130 Tunisian firms belonging to three key Tunisian industries. Findings The findings show that the managerial motivation, the firm’s characteristics in addition to environmental characteristics must be considered as antecedents to service orientation. The study has in fact verified the positive impact of service orientation on the firm’s performance and the fact that the business sector has a moderating effect on this relationship. Practical implications At the business level, marketing managers have to commit to finding new opportunities by valorizing market survey, establishing a management mechanism and controlling their service offer system. They have to try to internally “sell this service project” before thinking of adopting a service-oriented marketing strategy. However, industrial firms must equally take into account the services’ specificities for a better management of products/services. In fact, the intangible and the heterogeneous aspect of services increase risk perception and the degree of uncertainty among clients more than in a purchasing situation of a simple product. Consequently, marketing managers have to elaborate a specific approach, decide on a list of offered services, on their method and on quality standards to finally decide on the price. At the economic level, extending the service business has potential benefit for manufacturing firms and consequently for economy. Therefore, manufacturing firms seeking to invest in the service business must be encouraged by the government’s industrial policy. It is very important to help them overcome the obstacles to service adoption by providing financial incentives. In addition, it is very important to help them use and develop the technologies needed to improve the delivery of services. Originality/value In spite of the significant number of studies in this respect, the strategic perspective of service orientation was not as well developed as the organizational perspective and the theoretical development of this field remains underdeveloped. The authors noticed that the empirical applications of previous studies revealed divergent results that can be sometimes contradictory, particularly when they examine the impact of service orientation on performance. Besides, in recent research, “deservitization” appears as a solution adopted by managers who are unable to generate high revenues or margins to cover the additional investment in services. Consequently and considering the lack of consensus in previous studies, the authors’ principal objective is to identify the antecedents of service orientation and to test its impact on the industrial business performance. Additionally, and from an empirical point of view, the authors notice that the majority of past research on service orientation of industrial businesses was conducted in developed countries, whereas the empirical study of the present work was conducted in an emerging country in a transitional phase: Tunisia. Finally, because previous literature has assumed homogeneity on service strategies across sectors, the authors tried to show whether the business sector matters in terms of the relationship between service orientation and the manufacturing firm’s performance.

La Tunisie est toujours dépendante des importations pour satisfaire ses besoins en bois et produits dérivés à hauteur de 90 % malgré l’extension du couvert boisé de 500 000 ha environ au coursdescinq der- nières décennies. L’objectif principal de ce travail est d’apprécier la contribution des forêts à la satisfaction des besoins en bois industriel et son évolution au cours des cinq dernières décennies, et de déterminer la capacité desindustriesdu boisà valoriser le bois local. La consommation de bois industriel a augmenté de 0,19 M m3 en 1961 à 1,30 M m3 en 2012, alors que la production de bois industriel a augmenté de 0,09 M m3 seulement durant cette période. Dans un contexte de libéralisation des marchés, la valorisation du bois indus- triel et la maîtrise des importations ne peu- vent être réalisées que s’il existe une réelle coordination entre les acteurs de la filière bois (administration chargée de la gestion forestière et de la vente du bois, exploitants, industriels) permettant d’aboutir à la com- pétitivité des industries du bois. Une mise sur le marché de 50 000 m3 de bois sup- plémentaireset leur valorisation industrielle entraîneraient une recette additionnelle de 1,5 millions de dinars tunisiens (M DT) (+22 %) pour le budget de l’État, la réduction de la valeur des importations de 12 M DT (3 % des importations de bois et ouvrages en bois), et l’accroissement de la valeur ajoutée du secteur bois de 4 M DT, en plus de la création d’emploi au niveau de l’ex- ploitation et la transformation.

Much of the prior research on entrepreneurial orientation (EO) has focused on its determinants. This paper attempts to extend a point of view by which the EO allows to grasp the internal and external organizational conditions in order to update its business opportunities and innovate (Aloulou and Fayolle, 2005). The study examines the link between entrepreneurial orientation and innovation intensity through intellectual capital in a turbulent context. Research features were drawn in the light of the literature review and access to the ground. After stimulating the debate on the EO phenomenon and ensuring a critical revisit of its approach, the empirical basis was formed by 155 questionnaire surveys among industrial companies active in Tunisia. The mediating role of intellectual capital and the moderating role of environmental turbulence are highlighted while detecting the context specificities. Analysis reveals important contributions in the management research field.

RésuméLa présente contribution analyse un échantillon de dossiers de naturalisation concernant des étrangers italiens, polonais, portugais, algériens, marocains et tunisiens, résidents de l’agglomération de Longwy entre 1946 et 1990. Il en résulte que la population déclarée française doit être envisagée comme le point de croisement entre la volonté et la représentation de l’appartenance nationale de la part des cadres politico-administratifs et un ensemble de stratégies sociales de la part des étrangers. On peut distinguer trois constellations spécifiques renvoyant aux périodes 1950-1958, 1965-1975 et 1976-1990. En même temps, l’analyse fait voir l’émergence lente d’un modèle républicain de la naturalisation qui puise ses forces dans la stabilité des procédures administratives et dans la continuité du discours sur l’intégration. En pratique, la conception selon laquelle un individu est prêt et capable de faire partie harmonieusement de la « communauté française » a changé à partir du milieu des années 1970. La naturalisation est bien davantage devenue une ressource stratégique pour les immigrés, en particulier pour les jeunes, dans le cadre de trajectoires biographiques plus complexes et souvent très précaires. Surtout à l’égard de ces derniers, l’administration française a réagi en facilitant leur inclusion dans la communauté nationale.

In recent years, the evaluation of several energy sources is an extremely significant issue that affects socio-environmental development and techno-economic growth in different sectors. To tackle this concern, many researchers have concentrated on preferring desirable energy sources and adopting multi-criteria group decision-making (MCGDM) approaches for only a single type of user (e.g., agricultural, industrial, tourism, or domestic users). However, every energy user plays an important role in shaping energy policy. In fact, for sustainable energy, it is important to include all main energy users at the same time in energy decision-making. The main objective of this work was to propose a fuzzy MCGDM approach to evaluate and prioritize energy sources in Tunisia from various sectors’ point of views. Many criteria are combined, including the following: technical, economic, social, political and environmental. After applying the fuzzy Delphi method, the proposed approach consists of applying a fuzzy TOPSIS method as a multi-criteria approach. Finally, a sensitivity analysis is performed to evaluate the results of the proposed approach and to study how the optimal solution is affected by the objective function coefficients.

Introduction. Essential oils and their components are currently of great interest as a potential source of highly bioactive natural molecules. They are being studied for their possible use as safe alternative for food protection against oxidation and microbial spoilage. Objective. This study aimed on the phytochemical prospection of Thymus capitatus and Rosmainus officinalis essential oils and their oral toxicity evaluation. Material and methods. Chemical analysis of tested essential oils was carried out using gas chromatography combined to mass spectroscopic (GC-MS). Their safety limit was evaluated by acute toxicity. The antioxidant activity was estimated using in vitro methods. The antimicrobial activity was evaluated against twelve pathogenic germs. Results. Results showed that carvacrol and 1,8-cineol were the major compounds of Thymus capitatus and Rosmarinus officinalis essential oils. Acute toxicity results exhibited that both tested essential oils were inoffensive at 2000 mg/kg. Additionally, Thymus capitatus essential oil presented higher antioxidant activity than Rosmarinus officinalis: 2,2-diphényl-1-picrylhydrazyl (DPPH) assay results showed lower IC50 for Thymus capitatus essential oil than Rosmarinus officinalis. Concerning the antimicrobial results, Thymus capitatus essential oil presented greater efficacy than R. officinalis. Indeed, the minimal growth inhibition diameter generated by thyme essential oil exceeded 38 mm (except for Salmonella typhirium) and reached 60 mm (against C. tropicalis and C. albicans). However, the maximal growth inhibition diameter generated by R. officinalis essential oil was limited to 36 mm (against Shigella sonnei). Conclusion. Overall, Thymus capitatus and Rosmarinus officinalis essential oils have strong potential applicability for pharmaceutical industries.

Proposer une synthèse sur la préhistoire d’un archipel et de ses assemblages lithiques n’est pas chose facile, d’une part à cause de l’immensité de l’espace concerné mesurant 2 millions de km2, d’autre part du fait que la notion de Paléolithique y est difficilement applicable et notamment celles de « Paléolithique supérieur » ou d’Epipaléolithique-Mésolithique établies en Eurasie occidentale. L’Indonésie et ses myriades d’îles et îlots (environ 18000) s’inscrivent dans un rectangle 5000 km sur 2000 km de part et d’autre de l’équateur ce qui en fait le plus grand archipel du monde. Cette aire géographique immense s’étirant sur un espace maritime d’environ 6 millions de km2, ne nous permet pas aujourd’hui de traiter exhaustivement l’ensemble des groupes industriels, des faciès ou des cultures préhistoriques, c’est pour cela que nous aborderons les principaux. L’Indonésie occupe une place privilégiée pour l’histoire des hommes fossiles qui la rend incontournable dans les connaissances de la variabilité des comportements des hominidés en contexte intertropical. Cette contribution a pour objectif de dresser un bilan critique et objectif des différentes méthodes de taille rencontrées depuis 1 million d’années sur les principales îles à partir d’une sélection de sites dont la stratigraphie est bien établie et bien datée. Rares sont les technocomplexes bien définis avant l’Holocène, période où l’insularité de cette aire géographique s’est fixée avec la remontée marine marquant progressivement le début de l’histoire des archipels insulindiens. Parmi ceux-ci nous citerons le « Toalien » à Sulawesi (faciès à pointes), le « Sampungien » (faciès à pointes) et les industries sur éclats de Song Keplek ou « Keplekien » (débitage orthogonal) dans l’Est de l’île de Java. Hormis ces trois traditions techniques qui restent individualisables sur un plan typo-technologique, il n’y a pas dans l’ensemble du matériel rencontré, de faciès différentiables associés à une dénomination d’outils spécifiques. En règle générale, les industries lithiques du Pléistocène supérieur et de l’Holocène indonésien répondent à une production basique d’éclats et d’outils sur éclats avec de multiples variantes régionales. Le mode de débitage est très largement à la pierre dure, non Levallois, rarement Discoïde, non lamino-lamellaire tel qu’on peut le rencontrer en Europe de l’Ouest ou au Proche et Moyen-Orient. Contrairement à l’Asie du Sud-Est continentale où il est encore plus difficile de discerner un Paléolithique ancien, moyen et récent du fait de la continuité d’industries toutes réalisées sur galet (Hoabinhien et autres), l’Indonésie qui devient insulaire à la marge du Pléistocène et de l’Holocène propose une hétérogénéité des assemblages lithiques sans précédent. C’est-à-dire une diversité dans les modalités de production lithique selon différentes chaînes opératoires de façonnage (galet, pointe de type de Sampung, biface...) ou de débitage (discoïde, orthogonal et laminaire). Le but de cet article est donc de présenter de façon synthétique les principaux ensembles lithiques de l’Archipel indonésien à partir d’une sélection d’îles sur lesquelles des assemblages lithiques ont pu être correctement documentés. Nous nous intéresserons ainsi aux îles de Sumatra, de Java, de Kalimantan (Bornéo), de Sulawesi, et à quelques autres plus orientales qui, comme Timor et Flores, ont, ces dernières années, livré des découvertes de premier plan en paléoanthropologie et en préhistoire. Par commodité, nous avons été obligés de procéder à des coupures régionales et chronologiques (Pléistocène ancien-moyen et Pléistocène supérieur final-Holocène ancien) qui permettent d’exposer au mieux cette synthèse sur des assemblages lithiques qui n’ont pas tous fait l’objet d’études technologiques approfondies au sens où nous pouvons l’entendre en Europe avec l’utilisation du concept de chaîne opératoire.

Nowadays the telecommunications sector is becoming very complex Because of the panoply of high-speed technological services. Customers are abandoning the services offered by telecommunications operators because of their dissatisfaction with the services they offer. «Churn» or the migration of customers from one telecommunications operator to another is the main problem facing the telecommunications industries worldwide. Business managers consider the quality of service to be paramount. As a consequence, they have devised reliable criteria to assess the flow of customers within the market and check and evaluate whether customers are satisfied with the services they are offered. This, in turn, helps to establish customer loyalty and provide a healthy and sustainable trading agreement. Service quality control assessment is pivotal to identify the leverage and evaluate the internal and external competition in the industry. Although this concept is not foreign, rather it is an essential business management tool. The goal of this study is to determine the significant criteria for the cause migration of a Tunisie Telecom customer to another operator. Telecommunication is an essential lifelong component that contributes to the comfortability of our daily lives. The various means of telephone communication play a significant role in improving the effectiveness of communication industry. Every telecommunication operator is aware today that it is cheaper to retain an existing customer than to seek to recruit a new one. Indeed, we noticed that the telecommunications market is characterized by intense competition, where a change in the quality of service or a negative interaction perceived by the customer could risk losing them. As a result, the majority of operators introduce studies and action plans to retain customers and keep them as long as possible. The notion of keeping customers and building loyalty is probably one of the biggest challenges that operators around the world face in global competition. In order to achieve the goals set by telecom operators and to achieve maximum profitability, operators must effectively analyze market data and adopt a most effective targeted communications strategy for their customers. Keywords: churn analysis, customer loyalty, mobile marketing, telecommunications, telecommunications customer.

La préhistoire du Sud-est asiatique se caractérise par un matériel lithique dont les chaînes opératoires restent encore peu connues ou mal décrites. Cette méconnaissance s’explique par l’éloignement géographique de ces régions tropicales vis à vis des problématiques préhistoriques occidentales développées depuis maintenant deux siècles. La préhistoire de l’Extrême-Orient est complexe, originale, surprenante parfois paradoxale car en marge des grandes lignées techniques connues ailleurs pour la période concernée, celle qui a vu l’avènement de l’Homme anatomiquement moderne. Cette préhistoire régionale d’environ 2 millions de km2 que l’on nomme l’Asie du Sud-est péninsulaire ou continentale renvoie à l’élaboration d’une science en mouvement dont la construction est toujours d’actualité. En se heurtant à la thèse classique de l’évolution comme à celle du progrès technique, le Hoabinhien bouscule les règles et les repères en préhistoire. Il se situe aux antipodes du modèle classique (Eurasiatique, Africain) de développement des outils de pierre selon l’enrichissement et l’allègement progressif de l’outillage depuis la pebble culture jusqu’au Néolithique. C’est précisément sur cette singularité que porte notre réflexion à propos d’un phénomène technique unique qui reste difficile à positionner sur l’axe évolutif des industries tel qu’il existe ailleurs dans le monde ou en Asie de l’Est (Chine, Corée, Japon). La régularité et l’homogénéité des formes d’outils façonnées sur galet dans un vaste espace et sur une durée record de près de 30 000 ans sont les caractéristiques principales de ce technocomplexe peu orthodoxe qui interroge la capacité cognitive d’Homo sapiens en écosystème tropical humide. Mais aussi, la question de la nature des liens existants entre l’homme et ses productions lithiques ou la place occupée par la technique de la pierre taillée lors du développement humain dans cette région hors d’Europe.A cette monotone pérennité d’outils sur galet se greffe l’absence d’outils lithiques pointus (pointe, extrémité apicale, outil à bords saillants convergents, etc.) tels qu’ils se rencontrent partout ailleurs chez les groupes de chasseurs-cueilleurs qu’ils soient du Paléolithique supérieur ou (sub-)actuels.C’est pourquoi la stabilité de ces outillages sur galet cacherait tout un pan de complexité inconnu du domaine technique comme l’insaisissable travail des matières dures d’origine animale mais surtout végétale non conservées à ce jour dans les niveaux archéologiques. Le cheminement du minéral vers la question du végétal renvoie à la nécessité de compléter la « boîte à outils » des artisans préhistoriques hoabinhiens par des objets pointus. Connue à ce jour qu’à travers les données de l’ethnographie, la « civilisation du végétal » conduit tout naturellement à réfléchir sur l’importance de ce matériau périssable dans le bagage outillé des derniers chasseurs-cueilleurs de la forêt tropicale d’Asie du Sud-est continentale. Autrement dit, la possibilité d’une autre existence technique en équilibre avec le milieu extérieur.Après avoir mis en avant l’originalité du phénomène culturel hoabinhien au regard de l’impact de la recherche en préhistoire et en paléoanthropologie dans les régions du Sud-est asiatique, cet article présentera d’un point de vue strictement qualitatif, les chaînes opératoires du techno-complexe hoabinhien. Faciès industriel sur galet qui caractérise la principale culture technique des chasseurs-cueilleurs du Paléolithique final d’Asie du Sud-est entre environ 30 000 et 5 000 ans BP. Plus largement des précisions seront apportées d’une part sur l’inachèvement informatif du phénomène lithique en tant que donnée archéologique et d’autre part, sur son dépassement en tant que phénomène. Il s’agira donc de repenser l’envers de la dialectique lithique-lignic c’est-à-dire les objets du végétal à jamais disparus, à la lumière des objets de pierre taillée seuls conservés comme marqueurs de temps, de technique, d'espace et d’absence.

Environments containing significant concentration of NaCl such as salt lakes harbor extremophiles microorganisms which have a great biotechnology interest. To explore the diversity of Bacteria in Chott Tinsilt (Algeria), an isolation program was performed. Water samples were collected from the saltern during the pre-salt harvesting phase. This Chott is high in salt (22.47% (w/v). Seven halophiles Bacteria were selected for further characterization. The isolated strains were able to grow optimally in media with 10–25% (w/v) total salts. Molecular identification of the isolates was performed by sequencing the 16S rRNA gene. It showed that these cultured isolates included members belonging to the Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus genera with less than 98% of similarity with their closest phylogenetic relative. The halophilic bacterial isolates were also characterized for the production of biosurfactant and industrially important enzymes. Most isolates produced hydrolases and biosurfactants at high salt concentration. In fact, this is the first report on bacterial strains (A4 and B4) which were a good biosurfactant and coagulase producer at 20% and 25% ((w/v)) NaCl. In addition, the biosurfactant produced by the strain B4 at high salinity (25%) was also stable at high temperature (30-100°C) and high alkalinity (pH 11).Key word: Salt Lake, Bacteria, biosurfactant, Chott, halophiles, hydrolases, 16S rRNAINTRODUCTIONSaline lakes cover approximately 10% of the Earth’s surface area. The microbial populations of many hypersaline environments have already been studied in different geographical regions such as Great Salt Lake (USA), Dead Sea (Israel), Wadi Natrun Lake (Egypt), Lake Magadi (Kenya), Soda Lake (Antarctica) and Big Soda Lake and Mono Lake (California). Hypersaline regions differ from each other in terms of geographical location, salt concentration and chemical composition, which determine the nature of inhabitant microorganisms (Gupta et al., 2015). Then low taxonomic diversity is common to all these saline environments (Oren et al., 1993). Halophiles are found in nearly all major microbial clades, including prokaryotic (Bacteria and Archaea) and eukaryotic forms (DasSarma and Arora, 2001). They are classified as slight halophiles when they grow optimally at 0.2–0.85 M (2–5%) NaCl, as moderate halophiles when they grow at 0.85–3.4 M (5–20%) NaCl, and as extreme halophiles when they grow at 3.4–5.1 M (20–30%) NaCl. Hyper saline environments are inhabited by extremely halophilic and halotolerant microorganisms such as Halobacillus sp, Halobacterium sp., Haloarcula sp., Salinibacter ruber , Haloferax sp and Bacillus spp. (Solomon and Viswalingam, 2013). There is a tremendous demand for halophilic bacteria due to their biotechnological importance as sources of halophilic enzymes. Enzymes derived from halophiles are endowed with unique structural features and catalytic power to sustain the metabolic and physiological processes under high salt conditions. Some of these enzymes have been reported to be active and stable under more than one extreme condition (Karan and Khare, 2010). Applications are being considered in a range of industries such as food processing, washing, biosynthetic processes and environmental bioremediation. Halophilic proteases are widely used in the detergent and food industries (DasSarma and Arora, 2001). However, esterases and lipases have also been useful in laundry detergents for the removal of oil stains and are widely used as biocatalysts because of their ability to produce pure compounds. Likewise, amylases are used industrially in the first step of the production of high fructose corn syrup (hydrolysis of corn starch). They are also used in the textile industry in the de-sizing process and added to laundry detergents. Furthermore, for the environmental applications, the use of halophiles for bioremediation and biodegradation of various materials from industrial effluents to soil contaminants and accidental spills are being widely explored. In addition to enzymes, halophilic / halotolerants microorganisms living in saline environments, offer another potential applications in various fields of biotechnology like the production of biosurfactant. Biosurfactants are amphiphilic compounds synthesized from plants and microorganisms. They reduce surface tension and interfacial tension between individual molecules at the surface and interface respectively (Akbari et al., 2018). Comparing to the chemical surfactant, biosurfactant are promising alternative molecules due to their low toxicity, high biodegradability, environmental capability, mild production conditions, lower critical micelle concentration, higher selectivity, availability of resources and ability to function in wide ranges of pH, temperature and salinity (Rocha et al., 1992). They are used in various industries which include pharmaceuticals, petroleum, food, detergents, cosmetics, paints, paper products and water treatment (Akbari et al., 2018). The search for biosurfactants in extremophiles is particularly promising since these biomolecules can adapt and be stable in the harsh environments in which they are to be applied in biotechnology.OBJECTIVESEastern Algeria features numerous ecosystems including hypersaline environments, which are an important source of salt for food. The microbial diversity in Chott Tinsilt, a shallow Salt Lake with more than 200g/L salt concentration and a superficies of 2.154 Ha, has never yet been studied. The purpose of this research was to chemically analyse water samples collected from the Chott, isolate novel extremely or moderate halophilic Bacteria, and examine their phenotypic and phylogenetic characteristics with a view to screening for biosurfactants and enzymes of industrial interest.MATERIALS AND METHODSStudy area: The area is at 5 km of the Commune of Souk-Naâmane and 17 km in the South of the town of Aïn-Melila. This area skirts the trunk road 3 serving Constantine and Batna and the railway Constantine-Biskra. It is part the administrative jurisdiction of the Wilaya of Oum El Bouaghi. The Chott belongs to the wetlands of the High Plains of Constantine with a depth varying rather regularly without never exceeding 0.5 meter. Its length extends on 4 km with a width of 2.5 km (figure 1).Water samples and physico-chemical analysis: In February 2013, water samples were collected from various places at the Chott Tinsilt using Global Positioning System (GPS) coordinates of 35°53’14” N lat. and 06°28’44”E long. Samples were collected randomly in sterile polythene bags and transported immediately to the laboratory for isolation of halophilic microorganisms. All samples were treated within 24 h after collection. Temperature, pH and salinity were measured in situ using a multi-parameter probe (Hanna Instruments, Smithfield, RI, USA). The analytical methods used in this study to measure ions concentration (Ca2+, Mg2+, Fe2+, Na+, K+, Cl−, HCO3−, SO42−) were based on 4500-S-2 F standard methods described elsewhere (Association et al., 1920).Isolation of halophilic bacteria from water sample: The media (M1) used in the present study contain (g/L): 2.0 g of KCl, 100.0/200.0 g of NaCl, 1.0 g of MgSO4.7HO2, 3.0 g of Sodium Citrate, 0.36 g of MnCl2, 10.0 g of yeast extract and 15.0 g agar. The pH was adjusted to 8.0. Different dilutions of water samples were added to the above medium and incubated at 30°C during 2–7 days or more depending on growth. Appearance and growth of halophilic bacteria were monitored regularly. The growth was diluted 10 times and plated on complete medium agar (g/L): glucose 10.0; peptone 5.0; yeast extract 5.0; KH2PO4 5.0; agar 30.0; and NaCl 100.0/200.0. Resultant colonies were purified by repeated streaking on complete media agar. The pure cultures were preserved in 20% glycerol vials and stored at −80°C for long-term preservation.Biochemical characterisation of halophilic bacterial isolates: Bacterial isolates were studied for Gram’s reaction, cell morphology and pigmentation. Enzymatic assays (catalase, oxidase, nitrate reductase and urease), and assays for fermentation of lactose and mannitol were done as described by Smibert (1994).Optimization of growth conditions: Temperature, pH, and salt concentration were optimized for the growth of halophilic bacterial isolates. These growth parameters were studied quantitatively by growing the bacterial isolates in M1 medium with shaking at 200 rpm and measuring the cell density at 600 nm after 8 days of incubation. To study the effect of NaCl on the growth, bacterial isolates were inoculated on M1 medium supplemented with different concentration of NaCl: 1%-35% (w/v). The effect of pH on the growth of halophilic bacterial strains was studied by inoculating isolates on above described growth media containing NaCl and adjusted to acidic pH of 5 and 6 by using 1N HCl and alkaline pH of 8, 9, 10, 11 and 12 using 5N NaOH. The effect of temperature was studied by culturing the bacterial isolates in M1 medium at different temperatures of incubation (4°C–55°C).Screening of halophilic bacteria for hydrolytic enzymes: Hydrolase producing bacteria among the isolates were screened by plate assay on starch, tributyrin, gelatin and DNA agar plates respectively for amylase, lipase, protease and DNAse activities. Amylolytic activity of the cultures was screened on starch nutrient agar plates containing g/L: starch 10.0; peptone 5.0; yeast extract 3.0; agar 30.0; NaCl 100.0/250.0. The pH was 7.0. After incubation at 30 ºC for 7 days, the zone of clearance was determined by flooding the plates with iodine solution. The potential amylase producers were selected based on ratio of zone of clearance diameter to colony diameter. Lipase activity of the cultures was screened on tributyrin nutrient agar plates containing 1% (v/v) of tributyrin. Isolates that showed clear zones of tributyrin hydrolysis were identified as lipase producing bacteria. Proteolytic activity of the isolates was similarly screened on gelatin nutrient agar plates containing 10.0 g/L of gelatin. The isolates showing zones of gelatin clearance upon treatment with acidic mercuric chloride were selected and designated as protease producing bacteria. The presence of DNAse activity on plates was determined on DNAse test agar (BBL) containing 10%-25% (w/v) total salt. After incubation for 7days, the plates were flooded with 1N HCl solution. Clear halos around the colonies indicated DNAse activity (Jeffries et al., 1957).Milk clotting activity (coagulase activity) of the isolates was also determined following the procedure described (Berridge, 1952). Skim milk powder was reconstituted in 10 mM aqueous CaCl2 (pH 6.5) to a final concentration of 0.12 kg/L. Enzyme extracts were added at a rate of 0.1 mL per mL of milk. The coagulation point was determined by manual rotating of the test tube periodically, at short time intervals, and checking for visible clot formation.Screening of halophilic bacteria for biosurfactant production. Oil spread Assay: The Petridis base was filled with 50 mL of distilled water. On the water surface, 20μL of diesel and 10μl of culture were added respectively. The culture was introduced at different spots on the diesel, which is coated on the water surface. The occurrence of a clear zone was an indicator of positive result (Morikawa et al., 2000). The diameter of the oil expelling circles was measured by slide caliber (with a degree of accuracy of 0.02 mm).Surface tension and emulsification index (E24): Isolates were cultivated at 30 °C for 7 days on the enrichment medium containing 10-25% NaCl and diesel oil as the sole carbon source. The medium was centrifuged (7000 rpm for 20 min) and the surface tension of the cell-free culture broth was measured with a TS90000 surface tensiometer (Nima, Coventry, England) as a qualitative indicator of biosurfactant production. The culture broth was collected with a Pasteur pipette to remove the non-emulsified hydrocarbons. The emulsifying capacity was evaluated by an emulsification index (E24). The E24 of culture samples was determined by adding 2 mL of diesel oil to the same amount of culture, mixed for 2 min with a vortex, and allowed to stand for 24 h. E24 index is defined as the percentage of height of emulsified layer (mm) divided by the total height of the liquid column (mm).Biosurfactant stability studies : After growth on diesel oil as sole source of carbone, cultures supernatant obtained after centrifugation at 6,000 rpm for 15 min were considered as the source of crude biosurfactant. Its stability was determined by subjecting the culture supernatant to various temperature ranges (30, 40, 50, 60, 70, 80 and 100 °C) for 30 min then cooled to room temperature. Similarly, the effect of different pH (2–11) on the activity of the biosurfactant was tested. The activity of the biosurfactant was investigated by measuring the emulsification index (El-Sersy, 2012).Molecular identification of potential strains. DNA extraction and PCR amplification of 16S rDNA: Total cellular DNA was extracted from strains and purified as described by Sambrook et al. (1989). DNA was purified using Geneclean® Turbo (Q-BIO gene, Carlsbad, CA, USA) before use as a template in polymerase chain reaction (PCR) amplification. For the 16S rDNA gene sequence, the purified DNA was amplified using a universal primer set, forward primer (27f; 5′-AGA GTT TGA TCM TGG CTC AG) and a reverse primer (1492r; 5′-TAC GGY TAC CTT GTT ACG ACT T) (Lane, 1991). Agarose gel electrophoresis confirmed the amplification product as a 1400-bp DNA fragment.16S rDNA sequencing and Phylogenic analysis: Amplicons generated using primer pair 27f-1492r was sequenced using an automatic sequencer system at Macrogene Company (Seoul, Korea). The sequences were compared with those of the NCBI BLAST GenBank nucleotide sequence databases. Phylogenetic trees were constructed by the neighbor-joining method using MEGA version 5.05 software (Tamura et al., 2011). Bootstrap resembling analysis for 1,000 replicates was performed to estimate the confidence of tree topologies.Nucleotide sequence accession numbers: The nucleotide sequences reported in this work have been deposited in the EMBL Nucleotide Sequence Database. The accession numbers are represented in table 5.Statistics: All experiments were conducted in triplicates. Results were evaluated for statistical significance using ANOVA.RESULTSPhysico-chemical parameters of the collected water samples: The physicochemical properties of the collected water samples are reported in table 1. At the time of sampling, the temperature was 10.6°C and pH 7.89. The salinity of the sample, as determined in situ, was 224.70 g/L (22,47% (w/v)). Chemical analysis of water sample indicated that Na +and Cl- were the most abundant ions (table 1). SO4-2 and Mg+2 was present in much smaller amounts compared to Na +and Cl- concentration. Low levels of calcium, potassium and bicarbonate were also detected, often at less than 1 g/L.Characterization of isolates. Morphological and biochemical characteristic feature of halophilic bacterial isolates: Among 52 strains isolated from water of Chott Tinsilt, seven distinct bacteria (A1, A2, A3, A4, B1, B4 and B5) were chosen for further characterization (table 2). The colour of the isolates varied from beige, pale yellow, yellowish and orange. The bacterial isolates A1, A2, A4, B1 and B5 were rod shaped and gram negative (except B5), whereas A3 and B4 were cocci and gram positive. All strains were oxidase and catalase positive except for B1. Nitrate reductase and urease activities were observed in all the bacterial isolates, except B4. All the bacterial isolates were negative for H2S formation. B5 was the only strain positive for mannitol fermentation (table 2).We isolated halophilic bacteria on growth medium with NaCl supplementation at pH 7 and temperature of 30°C. We studied the effect of NaCl, temperature and pH on the growth of bacterial isolates. All the isolates exhibited growth only in the presence of NaCl indicating that these strains are halophilic. The optimum growth of isolates A3 and B1 was observed in the presence of 10% NaCl, whereas it was 15% NaCl for A1, A2 and B5. A4 and B4 showed optimum growth in the presence of 20% and 25% NaCl respectively. A4, B4 and B5 strains can tolerate up to 35% NaCl.The isolate B1 showed growth in medium supplemented with 10% NaCl and pH range of 7–10. The optimum pH for the growth B1 was 9 and they did not show any detectable growth at or below pH 6 (table 2), which indicates the alkaliphilic nature of B1 isolate. The bacterial isolates A1, A2 and A4 exhibited growth in the range of pH 6–10, while A3 and B4 did not show any growth at pH greater than 8. The optimum pH for growth of all strains (except B1) was pH 7.0 (table 2). These results indicate that A1, A2, A3, A4, B4 and B5 are neutrophilic in nature. All the bacterial isolates exhibited optimal growth at 30°C and no detectable growth at 55°C. Also, detectable growth of isolates A1, A2 and A4 was observed at 4°C. However, none of the bacterial strains could grow below 4°C and above 50°C (table 2).Screening of the halophilic enzymes: To characterize the diversity of halophiles able to produce hydrolytic enzymes among the population of microorganisms inhabiting the hypersaline habitats of East Algeria (Chott Tinsilt), a screening was performed. As described in Materials and Methods, samples were plated on solid media containing 10%-25% (w/v) of total salts and different substrates for the detection of amylase, protease, lipase and DNAse activities. However, coagulase activity was determined in liquid medium using milk as substrate (figure 3). Distributions of hydrolytic activity among the isolates are summarized in table 4.From the seven bacterial isolates, four strains A1, A2, A4 and B5 showed combined hydrolytic activities. They were positive for gelatinase, lipase and coagulase. A3 strain showed gelatinase and lipase activities. DNAse activities were detected with A1, A4, B1 and B5 isolates. B4 presented lipase and coagulase activity. Surprisingly, no amylase activity was detected among all the isolates.Screening for biosurfactant producing isolates: Oil spread assay: The results showed that all the strains could produce notable (>4 cm diameter) oil expelling circles (ranging from 4.11 cm to 4.67 cm). The average diameter for strain B5 was 4.67 cm, significantly (P < 0.05) higher than for the other strains.Surface tension and emulsification index (E24): The assimilation of hydrocarbons as the sole sources of carbon by the isolate strains led to the production of biosurfactants indicated by the emulsification index and the lowering of the surface tension of cell-free supernatant. Based on rapid growth on media containing diesel oil as sole carbon source, the seven isolates were tested for biosurfactant production and emulsification activity. The obtained values of the surface tension measurements as well as the emulsification index (E24) are shown in table 3. The highest reduction of surface tension was achieved with B5 and A3 isolates with values of 25.3 mN m−1 and 28.1 mN m−1 respectively. The emulsifying capacity evaluated by the E24 emulsification index was highest in the culture of isolate B4 (78%), B5 (77%) and A3 (76%) as shown in table 3 and figure 2. These emulsions were stable even after 4 months. The bacteria with emulsification indices higher than 50 % and/or reduction in the surface tension (under 30 mN/m) have been defined as potential biosurfactant producers. Based on surface tension and the E24 index results, isolates B5, B4, A3 and A4 are the best candidates for biosurfactant production. It is important to note that, strains B4 and A4 produce biosurfactant in medium containing respectively 25% and 20% (w/v) NaCl.Stability of biosurfactant activities: The applicability of biosurfactants in several biotechnological fields depends on their stability at different environmental conditions (temperatures, pH and NaCl). For this study, the strain B4 appear very interesting (It can produce biosurfactant at 25 % NaCl) and was choosen for futher analysis for biosurfactant stability. The effects of temperature and pH on the biosurfactant production by the strain B4 are shown in figure 4.biosurfactant in medium containing respectively 25% and 20% (w/v) NaCl.Stability of biosurfactant activities: The applicability of biosurfactants in several biotechnological fields depends on their stability at different environmental conditions (temperatures, pH and NaCl). For this study, the strain B4 appear very interesting (It can produce biosurfactant at 25 % NaCl) and was chosen for further analysis for biosurfactant stability. The effects of temperature and pH on the biosurfactant production by the strain B4 are shown in figure 4. The biosurfactant produced by this strain was shown to be thermostable giving an E-24 Index value greater than 78% (figure 4A). Heating of the biosurfactant to 100 °C caused no significant effect on the biosurfactant performance. Therefore, the surface activity of the crude biosurfactant supernatant remained relatively stable to pH changes between pH 6 and 11. At pH 11, the value of E24 showed almost 76% activity, whereas below pH 6 the activity was decreased up to 40% (figure 4A). The decreases of the emulsification activity by decreasing the pH value from basic to an acidic region; may be due to partial precipitation of the biosurfactant. This result indicated that biosurfactant produced by strain B4 show higher stability at alkaline than in acidic conditions.Molecular identification and phylogenies of potential isolates: To identify halophilic bacterial isolates, the 16S rDNA gene was amplified using gene-specific primers. A PCR product of ≈ 1.3 kb was detected in all the seven isolates. The 16S rDNA amplicons of each bacterial isolate was sequenced on both strands using 27F and 1492R primers. The complete nucleotide sequence of 1336,1374, 1377,1313, 1305,1308 and 1273 bp sequences were obtained from A1, A2, A3, A4, B1, B4 and B5 isolates respectively, and subjected to BLAST analysis. The 16S rDNA sequence analysis showed that the isolated strains belong to the genera Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus as shown in table 5. The halophilic isolates A2 and A4 showed 97% similarity with the Halomonas variabilis strain GSP3 (accession no. AY505527) and the Halomonas sp. M59 (accession no. AM229319), respectively. As for A1, it showed 96% similarity with the Halomonas venusta strain GSP24 (accession no. AY553074). B1 and B4 showed for their part 96% similarity with the Salinivibrio costicola subsp. alcaliphilus strain 18AG DSM4743 (accession no. NR_042255) and the Planococcus citreus (accession no. JX122551), respectively. The bacterial isolate B5 showed 98% sequence similarity with the Halobacillus trueperi (accession no. HG931926), As for A3, it showed only 95% similarity with the Staphylococcus arlettae (accession no. KR047785). The 16S rDNA nucleotide sequences of all the seven halophilic bacterial strains have been submitted to the NCBI GenBank database under the accession number presented in table 5. The phylogenetic association of the isolates is shown in figure 5.DICUSSIONThe physicochemical properties of the collected water samples indicated that this water was relatively neutral (pH 7.89) similar to the Dead Sea and the Great Salt Lake (USA) and in contrast to the more basic lakes such as Lake Wadi Natrun (Egypt) (pH 11) and El Golea Salt Lake (Algeria) (pH 9). The salinity of the sample was 224.70 g/L (22,47% (w/v). This range of salinity (20-30%) for Chott Tinsilt is comparable to a number of well characterized hypersaline ecosystems including both natural and man-made habitats, such as the Great Salt Lake (USA) and solar salterns of Puerto Rico. Thus, Chott Tinsilt is a hypersaline environment, i.e. environments with salt concentrations well above that of seawater. Chemical analysis of water sample indicated that Na +and Cl- were the most abundant ions, as in most hypersaline ecosystems (with some exceptions such as the Dead Sea). These chemical water characteristics were consistent with the previously reported data in other hypersaline ecosystems (DasSarma and Arora, 2001; Oren, 2002; Hacěne et al., 2004). Among 52 strains isolated from this Chott, seven distinct bacteria (A1, A2, A3, A4, B1, B4 and B5) were chosen for phenotypique, genotypique and phylogenetique characterization.The 16S rDNA sequence analysis showed that the isolated strains belong to the genera Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus. Genera obtained in the present study are commonly occurring in various saline habitats across the globe. Staphylococci have the ability to grow in a wide range of salt concentrations (Graham and Wilkinson, 1992; Morikawa et al., 2009; Roohi et al., 2014). For example, in Pakistan, Staphylococcus strains were isolated from various salt samples during the study conducted by Roohi et al. (2014) and these results agreed with previous reports. Halomonas, halophilic and/or halotolerant Gram-negative bacteria are typically found in saline environments (Kim et al., 2013). The presence of Planococcus and Halobacillus has been reported in studies about hypersaline lakes; like La Sal del Rey (USA) (Phillips et al., 2012) and Great Salt Lake (Spring et al., 1996), respectively. The Salinivibrio costicola was a representative model for studies on osmoregulatory and other physiological mechanisms of moderately halophilic bacteria (Oren, 2006).However, it is interesting to note that all strains shared less than 98.7% identity (the usual species cut-off proposed by Yarza et al. (2014) with their closest phylogenetic relative, suggesting that they could be considered as new species. Phenotypic, genetic and phylogenetic analyses have been suggested for the complete identification of these strains. Theses bacterial strains were tested for the production of industrially important enzymes (Amylase, protease, lipase, DNAse and coagulase). These isolates are good candidates as sources of novel enzymes with biotechnological potential as they can be used in different industrial processes at high salt concentration (up to 25% NaCl for B4). Prominent amylase, lipase, protease and DNAase activities have been reported from different hypersaline environments across the globe; e.g., Spain (Sánchez‐Porro et al., 2003), Iran (Rohban et al., 2009), Tunisia (Baati et al., 2010) and India (Gupta et al., 2016). However, to the best of our knowledge, the coagulase activity has never been detected in extreme halophilic bacteria. Isolation and characterization of crude enzymes (especially coagulase) to investigate their properties and stability are in progress.The finding of novel enzymes with optimal activities at various ranges of salt concentrations is of great importance. Besides being intrinsically stable and active at high salt concentrations, halophilic and halotolerant enzymes offer great opportunities in biotechnological applications, such as environmental bioremediation (marine, oilfiel) and food processing. The bacterial isolates were also characterized for production of biosurfactants by oil-spread assay, measurement of surface tension and emulsification index (E24). There are few reports on biosurfactant producers in hypersaline environments and in recent years, there has been a greater increase in interest and importance in halophilic bacteria for biomolecules (Donio et al., 2013; Sarafin et al., 2014). Halophiles, which have a unique lipid composition, may have an important role to play as surface-active agents. The archae bacterial ether-linked phytanyl membrane lipid of the extremely halophilic bacteria has been shown to have surfactant properties (Post and Collins, 1982). Yakimov et al. (1995) reported the production of biosurfactant by a halotolerant Bacillus licheniformis strain BAS 50 which was able to produce a lipopeptide surfactant when cultured at salinities up to 13% NaCl. From solar salt, Halomonas sp. BS4 and Kocuria marina BS-15 were found to be able to produce biosurfactant when cultured at salinities of 8% and 10% NaCl respectively (Donio et al., 2013; Sarafin et al., 2014). In the present work, strains B4 and A4 produce biosurfactant in medium containing respectively 25% and 20% NaCl. To our knowledge, this is the first report on biosurfactant production by bacteria under such salt concentration. Biosurfactants have a wide variety of industrial and environmental applications (Akbari et al., 2018) but their applicability depends on their stability at different environmental conditions. The strain B4 which can produce biosurfactant at 25% NaCl showed good stability in alkaline pH and at a temperature range of 30°C-100°C. Due to the enormous utilization of biosurfactant in detergent manufacture the choice of alkaline biosurfactant is researched (Elazzazy et al., 2015). On the other hand, the interesting finding was the thermostability of the produced biosurfactant even after heat treatment (100°C for 30 min) which suggests the use of this biosurfactant in industries where heating is of a paramount importance (Khopade et al., 2012). To date, more attention has been focused on biosurfactant producing bacteria under extreme conditions for industrial and commercial usefulness. In fact, the biosurfactant produce by strain B4 have promising usefulness in pharmaceutical, cosmetics and food industries and for bioremediation in marine environment and Microbial enhanced oil recovery (MEOR) where the salinity, temperature and pH are high.CONCLUSIONThis is the first study on the culturable halophilic bacteria community inhabiting Chott Tinsilt in Eastern Algeria. Different genera of halotolerant bacteria with different phylogeneticaly characteristics have been isolated from this Chott. Culturing of bacteria and their molecular analysis provides an opportunity to have a wide range of cultured microorganisms from extreme habitats like hypersaline environments. Enzymes produced by halophilic bacteria show interesting properties like their ability to remain functional in extreme conditions, such as high temperatures, wide range of pH, and high salt concentrations. These enzymes have great economical potential in industrial, agricultural, chemical, pharmaceutical, and biotechnological applications. Thus, the halophiles isolated from Chott Tinsilt offer an important potential for application in microbial and enzyme biotechnology. In addition, these halo bacterial biosurfactants producers isolated from this Chott will help to develop more valuable eco-friendly products to the pharmacological and food industries and will be usefulness for bioremediation in marine environment and petroleum industry.ACKNOWLEDGMENTSOur thanks to Professor Abdelhamid Zoubir for proofreading the English composition of the present paper.CONFLICT OF INTERESTThe authors declare that they have no conflict of interest.Akbari, S., N. H. Abdurahman, R. M. Yunus, F. Fayaz and O. R. Alara, 2018. Biosurfactants—a new frontier for social and environmental safety: A mini review. Biotechnology research innovation, 2(1): 81-90.Association, A. P. H., A. W. W. Association, W. P. C. 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Songolo River receives daily domestic and industrial wastewaters from households, laboratories, small and medium size industries (SMEs) and the Loandjili hospital, which are discharged directly into it without prior treatment. The objective of this study is to evaluate the physico- chemical quality of wastewaters discharged into the Songolo River at Pointe-Noire in Republic of Congo. To do this, 56 wastewater samples were taken. Physicochemical analyzes as temperature, pH, electronical conductivity, total dissolved solids, chloride ions, nitrate ions and total hydrocarbons, were carried out on wastewaters. These analyzes showed that in terms of time, during wet periods (April to June), the values of the physico-chemical parameters (conductivity, total dissolved solids, chlorides ions, nitrates ions and total hydrocarbons) are the lowest due to the dilution phenomenon brought by the rains. On the other hand, the beginning of the dry season (July) is marked by much higher levels. The results of physico-chemical analyzes of these effluents also revealed that conductivity, total dissolved solids and total hydrocarbons often have values higher than those recommended by the WHO standard for wastewaters intended for release into the natural environment.

Abstract This study evaluated the occurrence of extended-spectrum β-lactamases (ESBL) and associated resistance genes, integrons, and plasmid types as well as the genetic relatedness of enterobacterial isolates in the wastewater treatment plant (WWTP) of La Charguia, Tunis City (Tunisia). One-hundred water samples were collected at different points of the sewage treatment process during 2017–2019. Antimicrobial susceptibility was conducted by disc-diffusion method. blaCTX-M, blaTEM and blaSHV genes as well as those encoding non-β-lactam resistance, the plasmid types, occurrence of class1 integrons and phylogenetic groups of Escherichia coli isolates were determined by PCR/sequencing. Genomic relatedness was determined by MLST for selected isolates. Fifty-seven ESBL-producer isolates were recovered (47 E. coli, eight Klebsiella pneumoniae, one of the Citrobacter freundii complex and one of the Enterobacter cloacae complex). CTX-M-15 was the most frequently detected ESBL, followed by CTX-M-27, CTX-M-55 and SHV-12. One E. coli isolate harboured the mcr-1 gene. The following phylogroups/STs were identified among ESBL-producing E. coli isolates: B2/ST131 (subclade-C1), A/ST3221, A/ST8900, D/ST69, D/ST2142, D/ST38, B1/ST2460 and B1/ST6448. High number of isolates harboured the class 1 integrons with various gene cassette arrays as well as IncP-1 and IncFIB plasmids. Our findings confirm the importance of WWTPs as hotspot collectors of ESBL-producing Enterobacteriaceae with high likelihood spread to human and natural environment.

IntroductionAs the teaching staff working in a university postgraduate program—the Graduate Certificate of Creative Industries (Creative Practice) at Central Queensland University, Australia—an ongoing concern has been to ensure our students engage with the digital course content (delivered via the Moodle learning management system). This is an issue shared across the sector (La Pointe and Reisetter; Dargusch et al.) and, in our case, specifically in the area of students understanding how this online course content and tasks could benefit them in a program that is based around individual projects. As such, we are invested in enhancing student engagement both within the framework of this individual program and at an institution level. Like many institutions which now offer degrees which are either partially or fully online, the program in question offers a blended learning environment, with internal students also expected to engage with online materials (Rovai and Jordan; Colis and Moonen). The program was developed in 2011, first offered in 2012, and conducted two and sometimes three terms a year since then.Within the first year of delivery, low levels of student participation in online learning were identified as problematic. This issue was addressed using strategies that made use of characteristic strengths among our creative industries students, by developing and linking a peer-to-peer mentoring approach to our blended learning course design. Our challenge in this (as project facilitators and as teachers) has been to devise strategies to shift the students from reluctant to engaged online content users. A key strategy has evolved around introducing peer-mentoring as an intrinsic behaviour in the courses in the program. While not using a full case study approach, we do offer this singular instance for consideration as “much can be learned from a particular case” (Merriam 51). The below is based on our own observations, together with formal and informal student feedback gathered since 2012.Mentors and MentoringThe term mentor can have different meanings depending on the context in which the phrase is used. Ambrosetti and Dekkers note that “it is evident from the literature that there is no single definition for mentoring” (42). Drawing on an array of literature from a number of disciplines to qualify the definition of the term mentoring, Ambrosetti and Dekkers have identified a series of theorists whose definitions demonstrate the wide-ranging interpretation of what this act might be. Interestingly, they found that, even within the relatively narrow context of pre-service teacher research, words used to identify the term mentor varied from relatively collegial descriptors for the established teacher such as supporter, friend, collaborator, role model, and protector, to more formalised roles including trainer, teacher, assessor, and evaluator. The role to be played by a mentor—and how it is described—can also vary according to parameters around, and the purpose of, the mentoring relationship. That is, even though “mentoring, as described in literature, generally involves supporting and providing feedback to the mentee without judgment or criteria” (43), the dynamics of the mentor-mentee relationship may influence the perception and the nature of these roles. For example, the mentoring relationship between a teacher and pre-service teacher may be perceived as hierarchical whereby knowledge and feedback is “passed down” from mentor to mentee, that is, from a more authoritative, experienced figure to a less knowledgeable recipient. As such, this configuration implies a power imbalance between the roles.The relationships involved in peer-to-peer mentoring can be similarly defined. In fact, Colvin and Ashman describe the act of peer-mentoring as “a more experienced student helping a less experienced student improve overall academic performance”, and a relationship that “provides advice, support, and knowledge to the mentee” (122). Colvin and Ashman’s research also suggests that “if mentors and mentees do not have a clear sense of their roles and responsibilities, mentors will find it difficult to maintain any sort of self‐efficacy” (122)—a view that is held by others researchers in this field (see Hall et al.; Reid; Storrs, Putsche and Taylor). However, this collective view of peer-to-peer mentorship was not what we aimed to foster. Instead, we wanted our courses and program to both exhibit and inculcate practices and processes which we felt are more in line with our understanding of the creative industries, including a more organic, voluntary and non-hierarchical approach to peer-to-peer mentorship. This could use Ambrosetti and Dekker’s less hierarchical descriptors of supporter, friend, and collaborator listed above.Student CohortThe student cohort in this program regularly includes on-campus and distance education students in approximately equal ratios, with those studying by distance often geographically very widely dispersed across Australia, and sometimes internationally. The students in this program come from a diverse spectrum of creative industries’ art forms, including creative writing, digital media, film, music, and visual arts. Most enter the program with advanced skills, undergraduate or equivalent qualifications and/or considerable professional experience in their individual areas of creative practice and are seeking to add a postgraduate-level of understanding and scholarly extension to this practice (Kroll and Brien; Webb and Brien). Students also utilise a wide range of learning styles and approaches when developing and completing the creative works and research-informed reflective reports which comprise their assessment. All the students in the program’s courses utilise, and contribute to, a single online Moodle site each term. Some also wish to progress to research higher degree study in creative practice-led research projects (Barrett and Bolt) after completing the program.Applying Peer-to-Peer Mentoring in a Project-Based ProgramThe student cohort in this program is diverse, both geographically and in terms of the area of individual creative industries’ specialisation and the actual project that each student is working on. This diversity was a significant factor in the complexity of the challenge of how to make the course online site and its contents and tasks (required and optional) relevant and engaging for all students. We attempted to achieve this, in part, by always focusing on content and tasks directly related to the course learning outcomes and assessment tasks, so that their usefulness and authenticity in terms of the student learning journey was, we hoped, obvious to students. While this is a common practice in line with foundational conceptions of effective learning and teaching in higher education, we also proposed that we might be able to insure that course content was accessed and engaged with, and tasks completed, by linking the content and tasks in Moodle to the action of mentoring. In this, students were encouraged to discuss their projects in the online discussion forum throughout the term. This began with students offering brief descriptions of their projects as they worked through the project development stage, to reports on progress including challenges and problems as well as achievements. Staff input to these discussions offered guidance—both through example and (at times) gentle direction—on how students could also give collegial advice to other students on their projects. This was in terms of student knowledge and experience gained from previous work plus that learned during the program. In this, students reported on their own activities and how learning gained could potentially be used in other professional fields, as for example: “I specifically enjoyed the black out activity and found the online videos exceptional, inspiring and innovating. I really enjoyed this activity and it was something that I can take away and use within the classroom when educating” (‘Student 1’, week 8, Term 1 2015). Students also gave advice for others to follow: “I understand that this may not have been the original intended goal of Free Writing—but it is something I would highly recommend … students to try and see if it works for you” (‘Student 2’, week 5, Term 1 2015). As each term progressed, and trust built up—a key aspect of online collaboration (Holton) as well as a fruitful mentoring relationship (Allen and Poteet)—joint problem solving also began to take place in these discussions.As most of the students never interact face-to-face during the term, the relative impersonality of the online discussions in Moodle, although certainly not anonymous, seemed to provide a safe platform for peer-to-peer mentoring, even when this was offered by those who were also interacting in class as well. As facilitators of this process, we also sought to model best-practice interaction in this communication and ensure that any posts were responded to in an encouraging and timely manner (Aragon). As a result, the traffic within these forums generally increased each week so that, by the end of the term, every student (both external and internal) had contributed significantly to online discussions—even those who appeared to be more reluctant participants in the beginning weeks of the term. Strategies to Facilitate Peer-to-Peer MentoringSeeking to facilitate this process, we identified discrete points within the term’s course delivery at which we would encourage a greater level of engagement with the online resources and, through this, also encourage more discussion in the online discussion forum. One of the strategies we employed was to introduce specific interactions as compulsory components of the course but, at the same time, always ensuring that these mandated interactions related directly to assessment items. For example, a key assessment task requires students to write reflectively about their creative work and processes. We duly included information and examples of reflective writing as resources online. In order to further develop this skill for both internal and external students, we adopted an active and iterative learning approach to this task by asking students to write reflectively, each week, about the online resources provided to them. In asking students to do this, we reiterated that, at the end of term, a core part of the assessment item was that each student would be asked to describe, analyse and reflect on how they used these resources to facilitate their creative practice. At the end of the term, therefore, each student could collate his or her weekly responses, and use these as part of this assessment task. However, before this final reflection needed to be completed, these reflective musings were already being refined and extended as a result of the commentaries offered by other students responding to these weekly reflections. In this, these commenting students were, in fact, playing the role of peer-to-peer mentors, assisting each other to enhance their abilities in reflective thinking and writing.It should be stated that neither formal mentoring roles nor expectations of the process or its outcomes were pre-determined, defined or outlined to students by the teaching staff or communicated directly to them in any way (such as via the course materials). Instead, internal and distance students were encouraged to communicate with each other and offer guidance, help and support to each other (but which was never described as peer-to-peer mentorship) via their use of the Moodle learning managements system as both a group communication tool and a collaborative learning resource (Dixon, Dixon and Axmann). It is common for creative practitioners to collect data in the form of objects, resources, tools, and memories in order to progress their work and this habit has been termed that of the “bowerbird” (Brady). Knowing that it likely that many of our students are already proficient bowerbirds with many resources in their personal collections, we also facilitated a peer-to-peer mentoring activity in the form of an online competition. This competition asked students to post their favourite interactive resource onto the Moodle site, accompanied by a commentary explaining why and how it could be used. Many students engaged with these peer-posted resources and then, in turn, posted reflections on their usefulness, or not, for their own personal practice and learning. This, in turn, engendered more resources to be posted, shared, and discussed in terms of project problem-solving and, thus, became another ongoing activity that encouraged students to act as increasingly valued peer-mentors to each other.The Practical Application of Peer-to-Peer MentoringEach term, it is a course requirement that the student cohort, both internal and external, combine to create a group outcome—an exhibition of their creative work (Sturm, Beckton and Brien). For some students, the work exhibited is completed; for others, particularly part-time students, the work shown is frequently still in progress. Given that the work in the student exhibition regularly includes music and creative writing as well as visual art, this activity forces students to engage with their peers in ways that most of them have not previously encountered. This interaction includes communication across the internal and distance members of the cohort to determine what work will be included in the exhibition, and how work will be sent for display by external students, as well as liaising in relation to range of related considerations including: curatorial (what the exhibition will be named, and how work is to be displayed), cataloguing (how the works, and their contributors, are to be described), and the overall design of the catalogue and invitation (Sturm, Beckton and Brien). Students make these decisions, as a group, with guidance from staff mainly being offered in terms of practical information (such as what days and times the exhibition space can be accessed) and any limitations due to on-site health and safety considerations and other university-wide regulations.Student feedback has been very positive in relation to this aspect of the course (Sturm, Beckton and Brien), and its collective nature is often remarked on in both formal and informal feedback. We are also finding that some prospective students are applying to the program with a knowledge of this group exhibition and some information about how it is achieved. After graduation, students have reported that this experience of peer-to-peer working across the spectrum of creative industries’ art forms has given them a confidence that they were able to apply in real work situations and has, moreover been a factor that directly led to relevant employment. One student offered in unsolicited feedback: “It was a brilliant course that I gained a lot from. One year on, I have since released another single and work as an artist manager, independently running campaigns for other artists. The course also helped make me more employable as well, and I now work … as a casual admin and projects officer” (Student 3, 2015).Issues Arising from Peer-to-Peer MentoringAn intrinsic aspect of facilitating and encouraging this peer-to-peer mentoring was to allow a degree of latitude in relation to student online communication. The week-to-week reflection on the online resources was, for instance, the only mandated activity. Other participation was modeled and encouraged, but left to students as to how often and when they participated, as well as the length of their posts. In each term, we have found student involvement in discussions increased throughout the term, and tended to exceed our expectations in both quantity and quality of posts.We have also found that the level of intimate detail offered, and intimacy developed, in the communications was far greater than we had initially anticipated, and that there were occasions when students raised personal issues. Initially, we were apprehensive about this, particularly when one student discussed past mental health challenges. At the time, we discussed that the creative arts – whether in terms of its creation or appreciation – are highly personal practices (Sternberg), and that the tone taken by many of the creative individuals, theorists, and researchers whose materials we use as resources was often personally revealing (see, for example, Brien and Brady). By not interfering, other than ensuring that the tone students used with each other was always respectful and focused on the professional aspects of what was being discussed, we observed that this personal revelation translated into high levels of engagement in the discussions, and indeed, encouraged peer support and understanding. Thus, in terms of the student who revealed information about past health issues and who at one stage had considered withdrawing from the course, this student later related to staff—in an unsolicited communication—that these discussions led to him feeling well supported. This student has, moreover, continued to work on related creative practice projects after completing the program and, indeed, is now considering continuing onto Masters level studies.ConclusionIn relation to much of the literature of mentoring, this experience of student interaction with others through an online discussion board appears to offer a point of difference. While that literature reports on other examples of peer-to-peer mentoring, most of these follow the seemingly more usual vertical mentoring model (that is, one which is hierarchical), rather than what developed organically in our case as a more horizontal mode. This is, moreover, a mode which has many synergies with the community of practice and collaborative problem solving models which are central to the creative industries (Brien and Bruns).Collings, Swanson, and Watkins have reported on the positive impact of peer mentoring on student wellbeing, integration, and retention. In terms of effects and student outcomes, although we have not yet collected data on these aspects of this activity, our observations together with informal and University-solicited feedback suggests that this peer-to-peer mentoring was useful (in terms of their project work) and affirming and confidence-building (personally and professionally) for students who are both mentors and mentees. These peer-to-peer mentoring activities assisted in developing, and was encouraged by, an atmosphere in which students felt it was appropriate and safe to both offer support and critique of each others’ work and ideas, as well as encouragement when students felt discouraged or creatively blocked. Students, indeed, reported in class and online that this input assisted them in moving through their projects and, as program staff, we saw that that this online space created a place where collaborative problem-solving could be engaged in as the need arose—rather than in a more forced manner. As teachers, we also found these students became our post-graduate colleagues in the way more usually experienced in the doctoral supervisor-student relationship (Dibble and Loon).The above reports on a responsive learning and teaching strategy that grew out of our understanding of our students’ needs that was, moreover, in line with our institution’s imperatives. We feel this was a successful and authentic way of involving students in online discussions, although we did not originally foresee that they would become mentors in the process. The next step is to develop a project to formally evaluate this aspect of this program and our teaching, as well as whether (or how) they reflect the overarching discipline of the creative industries in terms of process and philosophy. ReferencesAllen, Tammy D., and Mark L. Poteet. “Developing Effective Mentoring Relationships: Strategies from the Mentor’s Viewpoint.” The Career Development Quarterly 48.1 (1999): 59–57.Ambosetti, Angelina, and John Dekkers. “The Interconnectedness of the Roles of Mentors and Mentees in Pre-Service Teacher Education Mentoring Relationships.” Australian Journal of Teaching Education 35.6 (2010): 42–55.Aragon, Steven R. “Creating Social Presence in Online Environments.” New Directions for Adult and Continuing Education 100 (2003): 57–68. Barrett, Estelle, and Barbara Bolt, eds. Practice as Research: Approaches to Creative Arts Enquiry. London: I.B. Tauris, 2007.Brady, Tess. “A Question of Genre: Demystifying the Exegesis.” TEXT: Journal of the Australian Association of Writing Programs 4.1 (2000). 1 Mar. 2016 <http://www.textjournal.com.au/april00/brady.htm>.Brien, Donna Lee, and Tess Brady. “Collaborative Practice: Categorising Forms of Collaboration for Practitioners.” TEXT: The Journal of the Australian Association of Writing Programs 7.2 (2003). 1 Mar. 2016 <http://www.textjournal.com.au/oct03/brienbrady.htm>.Brien, Donna Lee, and Axel Bruns. “Editorial.” M/C Journal 9.2 (2006) 1 Mar. 2016 <http://www.textjournal.com.au/oct03/brienbrady.htm>.Central Queensland University. CB82 Graduate Certificate in Creative Industries. 2016. 1 Mar. 2016 <http://handbook.cqu.edu.au/programs/index?programCode=CB82>.Colis, B., and J. Moonen. Flexible Learning in a Digital World: Experiences and Expectations. London: Kogan-Page, 2001.Collings, R., V. Swanson and R. Watkins. “The Impact of Peer Mentoring on Levels of Student Wellbeing, Integration and Retention: A Controlled Comparative Evaluation of Residential Students in U.K. Higher Education.” Higher Education 68 (2014): 927–42.Colvin, Janet W., and Miranda Ashman. “Roles, Risks and Benefits of Peer Mentoring Relationships in Higher Education.” Mentoring and Tutoring: Partnership in Learning 18.2 (2010): 121–34. Dargusch, Joanne, Lois R. Harris, Kerry Reid-Searl, and Benjamin Taylor. “Getting the Message Through: Communicating Assessment Expectations to First Year Students.” Australian Association of Research in Education Conference. Fremantle, WA: 2015.Dibble, Brian, and Julienne van Loon. “The Higher Degree Research Journey as a Three Legged Race.” TEXT: Journal of the Australian Association of Writing Programs 8.2 (2004). 20 Feb. 2016 <http://www.textjournal.com.au/oct04/dibble_vanloon.htm>.Dixon, Robert, Kathryn Dixon, and Mandi Axmann. “Online Student Centred Discussion: Creating a Collaborative Learning Environment.” Hello! Where Are You in the Landscape of Educational Technology: Proceedings ASCILITE. Melbourne: ASCILITE, 2008. 256–264.Hall, Kendra M., Rani Jo Draper, Leigh K. Smith, and Robert V. Bullough. “More than a Place to Teach: Exploring the Perceptions of the Roles and Responsibilities of Mentor Teachers.” Mentoring & Tutoring: Partnership in Learning 16.3 (2008): 328–45.Holton, Judith A. “Building Trust and Collaboration in a Virtual Team.” Team Performance Management: An International Journal 7.3/4 (2001): 36–47.Kroll, Jeri, and Donna Lee Brien. “Studying for the Future: Training Creative Writing Postgraduates for Life after Degrees.” Australian Online Journal of Arts Education 2.1 (2006): 1–13.La Pointe, Loralee, and Marcy Reisetter. “Belonging Online: Students’ Perceptions of the Value and Efficacy of an Online Learning Community.” International Journal on E-Learning 7.4 (2008): 641–65.Merriam, Sharan B. Qualitative Research: A Guide to Design and Implementation. San Francisco, CA: Jossey-Bass, 2009.Reid, E. Shelley. “Mentoring Peer Mentors: Mentor Education and Support in the Composition Program.” Composition Studies 36.2 (2008): 51–79.Rovai, A.P., and Hope M. Jordan. “Blended Learning and Sense of Community: A Comparative Analysis with Traditional and Fully Online Graduate Courses.” Virginia: Regent University, 2004. 20 Feb. 2016 <http://www.irrodl.org/index.php/irrodl/article/view/192/274>.Storrs, D., L. Putsche, and A. Taylor. “Mentoring Expectations and Realities: An Analysis of Metaphorical Thinking among Female Undergraduate Protégés and Their Mentors in a University Mentoring Programme.” Mentoring & Tutoring: Partnership in Learning 16.2 (2008): 175–88. Sternberg, Robert. The Nature of Creativity: Contemporary Psychological Perspectives. Cambridge: Cambridge UP, 1988.Sturm, Ulrike, Denise Beckton, and Donna Lee Brien. “Curation on Campus: An Exhibition Curatorial Experiment for Creative Industries Students.” M/C Journal 18.4 (2015). 12 Feb. 2016 <http://journal.media-culture.org.au/index.php/mcjournal/article/view/1000>.Webb, Jen, and Donna Lee Brien. “Preparing Graduates for Creative Futures: Australian Creative Arts Programs in a Globalising Society.” Partnerships for World Graduates: AIC (Academia, Industry and Community) 2007 Conference. Melbourne: RMIT, 28–30 November 2007.

Lists and Social MediaLists have long been an ordering mechanism for computer-mediated social interaction. While far from being the first such mechanism, blogrolls offered an opportunity for bloggers to provide a list of their peers; the present generation of social media environments similarly provide lists of friends and followers. Where blogrolls and other earlier lists may have been user-generated, the social media lists of today are more likely to have been produced by the platforms themselves, and are of intrinsic value to the platform providers at least as much as to the users themselves; both Facebook and Twitter have highlighted the importance of their respective “social graphs” (their databases of user connections) as fundamental elements of their fledgling business models. This represents what Mejias describes as “nodocentrism,” which “renders all human interaction in terms of network dynamics (not just any network, but a digital network with a profit-driven infrastructure).”The communicative content of social media spaces is also frequently rendered in the form of lists. Famously, blogs are defined in the first place by their reverse-chronological listing of posts (Walker Rettberg), but the same is true for current social media platforms: Twitter, Facebook, and other social media platforms are inherently centred around an infinite, constantly updated and extended list of posts made by individual users and their connections.The concept of the list implies a certain degree of order, and the orderliness of content lists as provided through the latest generation of centralised social media platforms has also led to the development of more comprehensive and powerful, commercial as well as scholarly, research approaches to the study of social media. Using the example of Twitter, this article discusses the challenges of such “big data” research as it draws on the content lists provided by proprietary social media platforms.Twitter Archives for ResearchTwitter is a particularly useful source of social media data: using the Twitter API (the Application Programming Interface, which provides structured access to communication data in standardised formats) it is possible, with a little effort and sufficient technical resources, for researchers to gather very large archives of public tweets concerned with a particular topic, theme or event. Essentially, the API delivers very long lists of hundreds, thousands, or millions of tweets, and metadata about those tweets; such data can then be sliced, diced and visualised in a wide range of ways, in order to understand the dynamics of social media communication. Such research is frequently oriented around pre-existing research questions, but is typically conducted at unprecedented scale. The projects of media and communication researchers such as Papacharissi and de Fatima Oliveira, Wood and Baughman, or Lotan, et al.—to name just a handful of recent examples—rely fundamentally on Twitter datasets which now routinely comprise millions of tweets and associated metadata, collected according to a wide range of criteria. What is common to all such cases, however, is the need to make new methodological choices in the processing and analysis of such large datasets on mediated social interaction.Our own work is broadly concerned with understanding the role of social media in the contemporary media ecology, with a focus on the formation and dynamics of interest- and issues-based publics. We have mined and analysed large archives of Twitter data to understand contemporary crisis communication (Bruns et al), the role of social media in elections (Burgess and Bruns), and the nature of contemporary audience engagement with television entertainment and news media (Harrington, Highfield, and Bruns). Using a custom installation of the open source Twitter archiving tool yourTwapperkeeper, we capture and archive all the available tweets (and their associated metadata) containing a specified keyword (like “Olympics” or “dubstep”), name (Gillard, Bieber, Obama) or hashtag (#ausvotes, #royalwedding, #qldfloods). In their simplest form, such Twitter archives are commonly stored as delimited (e.g. comma- or tab-separated) text files, with each of the following values in a separate column: text: contents of the tweet itself, in 140 characters or less to_user_id: numerical ID of the tweet recipient (for @replies) from_user: screen name of the tweet sender id: numerical ID of the tweet itself from_user_id: numerical ID of the tweet sender iso_language_code: code (e.g. en, de, fr, ...) of the sender’s default language source: client software used to tweet (e.g. Web, Tweetdeck, ...) profile_image_url: URL of the tweet sender’s profile picture geo_type: format of the sender’s geographical coordinates geo_coordinates_0: first element of the geographical coordinates geo_coordinates_1: second element of the geographical coordinates created_at: tweet timestamp in human-readable format time: tweet timestamp as a numerical Unix timestampIn order to process the data, we typically run a number of our own scripts (written in the programming language Gawk) which manipulate or filter the records in various ways, and apply a series of temporal, qualitative and categorical metrics to the data, enabling us to discern patterns of activity over time, as well as to identify topics and themes, key actors, and the relations among them; in some circumstances we may also undertake further processes of filtering and close textual analysis of the content of the tweets. Network analysis (of the relationships among actors in a discussion; or among key themes) is undertaken using the open source application Gephi. While a detailed methodological discussion is beyond the scope of this article, further details and examples of our methods and tools for data analysis and visualisation, including copies of our Gawk scripts, are available on our comprehensive project website, Mapping Online Publics.In this article, we reflect on the technical, epistemological and political challenges of such uses of large-scale Twitter archives within media and communication studies research, positioning this work in the context of the phenomenon that Lev Manovich has called “big social data.” In doing so, we recognise that our empirical work on Twitter is concerned with a complex research site that is itself shaped by a complex range of human and non-human actors, within a dynamic, indeed volatile media ecology (Fuller), and using data collection and analysis methods that are in themselves deeply embedded in this ecology. “Big Social Data”As Manovich’s term implies, the Big Data paradigm has recently arrived in media, communication and cultural studies—significantly later than it did in the hard sciences, in more traditionally computational branches of social science, and perhaps even in the first wave of digital humanities research (which largely applied computational methods to pre-existing, historical “big data” corpora)—and this shift has been provoked in large part by the dramatic quantitative growth and apparently increased cultural importance of social media—hence, “big social data.” As Manovich puts it: For the first time, we can follow [the] imaginations, opinions, ideas, and feelings of hundreds of millions of people. We can see the images and the videos they create and comment on, monitor the conversations they are engaged in, read their blog posts and tweets, navigate their maps, listen to their track lists, and follow their trajectories in physical space. (Manovich 461) This moment has arrived in media, communication and cultural studies because of the increased scale of social media participation and the textual traces that this participation leaves behind—allowing researchers, equipped with digital tools and methods, to “study social and cultural processes and dynamics in new ways” (Manovich 461). However, and crucially for our purposes in this article, many of these scholarly possibilities would remain latent if it were not for the widespread availability of Open APIs for social software (including social media) platforms. APIs are technical specifications of how one software application should access another, thereby allowing the embedding or cross-publishing of social content across Websites (so that your tweets can appear in your Facebook timeline, for example), or allowing third-party developers to build additional applications on social media platforms (like the Twitter user ranking service Klout), while also allowing platform owners to impose de facto regulation on such third-party uses via the same code. While platform providers do not necessarily have scholarship in mind, the data access affordances of APIs are also available for research purposes. As Manovich notes, until very recently almost all truly “big data” approaches to social media research had been undertaken by computer scientists (464). But as part of a broader “computational turn” in the digital humanities (Berry), and because of the increased availability to non-specialists of data access and analysis tools, media, communication and cultural studies scholars are beginning to catch up. Many of the new, large-scale research projects examining the societal uses and impacts of social media—including our own—which have been initiated by various media, communication, and cultural studies research leaders around the world have begun their work by taking stock of, and often substantially extending through new development, the range of available tools and methods for data analysis. The research infrastructure developed by such projects, therefore, now reflects their own disciplinary backgrounds at least as much as it does the fundamental principles of computer science. In turn, such new and often experimental tools and methods necessarily also provoke new epistemological and methodological challenges. The Twitter API and Twitter ArchivesThe Open API was a key aspect of mid-2000s ideas about the value of the open Web and “Web 2.0” business models (O’Reilly), emphasising the open, cross-platform sharing of content as well as promoting innovation at the margins via third-party application development—and it was in this ideological environment that the microblogging service Twitter launched and experienced rapid growth in popularity among users and developers alike. As José van Dijck cogently argues, however, a complex interplay of technical, economic and social dynamics has seen Twitter shift from a relatively open, ad hoc and user-centred platform toward a more formalised media business: For Twitter, the shift from being primarily a conversational communication tool to being a global, ad-supported followers tool took place in a relatively short time span. This shift did not simply result from the owner’s choice for a distinct business model or from the company’s decision to change hardware features. Instead, the proliferation of Twitter as a tool has been a complex process in which technological adjustments are intricately intertwined with changes in user base, transformations of content and choices for revenue models. (van Dijck 343)The specifications of Twitter’s API, as well as the written guidelines for its use by developers (Twitter, “Developer Rules”) are an excellent example of these “technological adjustments” and the ways they are deeply interwined with Twitter’s search for a viable revenue model. These changes show how the apparent semantic openness or “interpretive flexibility” of the term “platform” allows its meaning to be reshaped over time as the business models of platform owners change (Gillespie).The release of the API was first announced on the Twitter blog in September 2006 (Stone), not long after the service’s launch but after some popular third-party applications (like a mashup of Twitter with Google Maps creating a dynamic display of recently posted tweets around the world) had already been developed. Since then Twitter has seen a flourishing of what the company itself referred to as the “Twitter ecosystem” (Twitter, “Developer Rules”), including third-party developed client software (like Twitterific and TweetDeck), institutional use cases (such as large-scale social media visualisations of the London Riots in The Guardian), and parasitic business models (including social media metrics services like HootSuite and Klout).While the history of Twitter’s API rules and related regulatory instruments (such as its Developer Rules of the Road and Terms of Use) has many twists and turns, there have been two particularly important recent controversies around data access and control. First, the company locked out developers and researchers from direct “firehose” (very high volume) access to the Twitter feed; this was accompanied by a crackdown on free and public Twitter archiving services like 140Kit and the Web version of Twapperkeeper (Sample), and coincided with the establishment of what was at the time a monopoly content licensing arrangement between Twitter and Gnip, a company which charges commercial rates for high-volume API access to tweets (and content from other social media platforms). A second wave of controversy among the developer community occurred in August 2012 in response to Twitter’s release of its latest API rules (Sippey), which introduce further, significant limits to API use and usability in certain circumstances. In essence, the result of these changes to the Twitter API rules, announced without meaningful consultation with the developer community which created the Twitter ecosystem, is a forced rebalancing of development activities: on the one hand, Twitter is explicitly seeking to “limit” (Sippey) the further development of API-based third-party tools which support “consumer engagement activities” (such as end-user clients), in order to boost the use of its own end-user interfaces; on the other hand, it aims to “encourage” the further development of “consumer analytics” and “business analytics” as well as “business engagement” tools. Implicit in these changes is a repositioning of Twitter users (increasingly as content consumers rather than active communicators), but also of commercial and academic researchers investigating the uses of Twitter (as providing a narrow range of existing Twitter “analytics” rather than engaging in a more comprehensive investigation both of how Twitter is used, and of how such uses continue to evolve). The changes represent an attempt by the company to cement a certain, commercially viable and valuable, vision of how Twitter should be used (and analysed), and to prevent or at least delay further evolution beyond this desired stage. Although such attempts to “freeze” development may well be in vain, given the considerable, documented role which the Twitter user base has historically played in exploring new and unforeseen uses of Twitter (Bruns), it undermines scholarly research efforts to examine actual Twitter uses at least temporarily—meaning that researchers are increasingly forced to invest time and resources in finding workarounds for the new restrictions imposed by the Twitter API.Technical, Political, and Epistemological IssuesIn their recent article “Critical Questions for Big Data,” danah boyd and Kate Crawford have drawn our attention to the limitations, politics and ethics of big data approaches in the social sciences more broadly, but also touching on social media as a particularly prevalent site of social datamining. In response, we offer the following complementary points specifically related to data-driven Twitter research relying on archives of tweets gathered using the Twitter API.First, somewhat differently from most digital humanities (where researchers often begin with a large pre-existing textual corpus), in the case of Twitter research we have no access to an original set of texts—we can access only what Twitter’s proprietary and frequently changing API will provide. The tools Twitter researchers use rely on various combinations of parts of the Twitter API—or, more accurately, the various Twitter APIs (particularly the Search and Streaming APIs). As discussed above, of course, in providing an API, Twitter is driven not by scholarly concerns but by an attempt to serve a range of potentially value-generating end-users—particularly those with whom Twitter can create business-to-business relationships, as in their recent exclusive partnership with NBC in covering the 2012 London Olympics.The following section from Twitter’s own developer FAQ highlights the potential conflicts between the business-case usage scenarios under which the APIs are provided and the actual uses to which they are often put by academic researchers or other dataminers:Twitter’s search is optimized to serve relevant tweets to end-users in response to direct, non-recurring queries such as #hashtags, URLs, domains, and keywords. The Search API (which also powers Twitter’s search widget) is an interface to this search engine. Our search service is not meant to be an exhaustive archive of public tweets and not all tweets are indexed or returned. Some results are refined to better combat spam and increase relevance. Due to capacity constraints, the index currently only covers about a week’s worth of tweets. (Twitter, “Frequently Asked Questions”)Because external researchers do not have access to the full, “raw” data, against which we could compare the retrieved archives which we use in our later analyses, and because our data access regimes rely so heavily on Twitter’s APIs—each with its technical quirks and limitations—it is impossible for us to say with any certainty that we are capturing a complete archive or even a “representative” sample (whatever “representative” might mean in a data-driven, textualist paradigm). In other words, the “lists” of tweets delivered to us on the basis of a keyword search are not necessarily complete; and there is no way of knowing how incomplete they are. The total yield of even the most robust capture system (using the Streaming API and not relying only on Search) depends on a number of variables: rate limiting, the filtering and spam-limiting functions of Twitter’s search algorithm, server outages and so on; further, because Twitter prohibits the sharing of data sets it is difficult to compare notes with other research teams.In terms of epistemology, too, the primary reliance on large datasets produces a new mode of scholarship in media, communication and cultural studies: what emerges is a form of data-driven research which tends towards abductive reasoning; in doing so, it highlights tensions between the traditional research questions in discourse or text-based disciplines like media and communication studies, and the assumptions and modes of pattern recognition that are required when working from the “inside out” of a corpus, rather than from the outside in (for an extended discussion of these epistemological issues in the digital humanities more generally, see Dixon).Finally, even the heuristics of our analyses of Twitter datasets are mediated by the API: the datapoints that are hardwired into the data naturally become the most salient, further shaping the type of analysis that can be done. For example, a common process in our research is to use the syntax of tweets to categorise it as one of the following types of activity: original tweets: tweets which are neither @reply nor retweetretweets: tweets which contain RT @user… (or similar) unedited retweets: retweets which start with RT @user… edited retweets: retweets do not start with RT @user…genuine @replies: tweets which contain @user, but are not retweetsURL sharing: tweets which contain URLs(Retweets which are made using the Twitter “retweet button,” resulting in verbatim passing-along without the RT @user syntax or an opportunity to add further comment during the retweet process, form yet another category, which cannot be tracked particularly effectively using the Twitter API.)These categories are driven by the textual and technical markers of specific kinds of interactions that are built into the syntax of Twitter itself (@replies or @mentions, RTs); and specific modes of referentiality (URLs). All of them focus on (and thereby tend to privilege) more informational modes of communication, rather than the ephemeral, affective, or ambiently intimate uses of Twitter that can be illuminated more easily using ethnographic approaches: approaches that can actually focus on the individual user, their social contexts, and the broader cultural context of the traces they leave on Twitter. ConclusionsIn this article we have described and reflected on some of the sociotechnical, political and economic aspects of the lists of tweets—the structured Twitter data upon which our research relies—which may be gathered using the Twitter API. As we have argued elsewhere (Bruns and Burgess)—and, hopefully, have begun to demonstrate in this paper—media and communication studies scholars who are actually engaged in using computational methods are well-positioned to contribute to both the methodological advances we highlight at the beginning of this paper and the political debates around computational methods in the “big social data” moment on which the discussion in the second part of the paper focusses. One pressing issue in the area of methodology is to build on current advances to bring together large-scale datamining approaches with ethnographic and other qualitative approaches, especially including close textual analysis. More broadly, in engaging with the “big social data” moment there is a pressing need for the development of code literacy in media, communication and cultural studies. In the first place, such literacy has important instrumental uses: as Manovich argues, much big data research in the humanities requires costly and time-consuming (and sometimes alienating) partnerships with technical experts (typically, computer scientists), because the free tools available to non-programmers are still limited in utility in comparison to what can be achieved using raw data and original code (Manovich, 472).But code literacy is also a requirement of scholarly rigour in the context of what David Berry calls the “computational turn,” representing a “third wave” of Digital Humanities. Berry suggests code and software might increasingly become in themselves objects of, and not only tools for, research: I suggest that we introduce a humanistic approach to the subject of computer code, paying attention to the wider aspects of code and software, and connecting them to the materiality of this growing digital world. With this in mind, the question of code becomes increasingly important for understanding in the digital humanities, and serves as a condition of possibility for the many new computational forms that mediate our experience of contemporary culture and society. (Berry 17)A first step here lies in developing a more robust working knowledge of the conceptual models and methodological priorities assumed by the workings of both the tools and the sources we use for “big social data” research. Understanding how something like the Twitter API mediates the cultures of use of the platform, as well as reflexively engaging with its mediating role in data-driven Twitter research, promotes a much more materialist critical understanding of the politics of the social media platforms (Gillespie) that are now such powerful actors in the media ecology. ReferencesBerry, David M. “Introduction: Understanding Digital Humanities.” Understanding Digital Humanities. Ed. David M. Berry. 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