Journal articles on the topic 'Defined and undefined starter cultures'
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1
Giraffa, Giorgio. "The Microbiota of Grana Padano Cheese. A Review." Foods 10, no. 11 (October 29, 2021): 2632. http://dx.doi.org/10.3390/foods10112632.
Abstract:
Grana Padano (GP) is the most appreciated and marketed cheese with Protected Designation of Origin in the world. The use of raw milk, the addition of undefined cultures (defined as ‘sieroinnesto naturale’), the peculiar manufacturing proces, and the long ripening make the cheese microbiota play a decisive role in defining the quality and the organoleptic properties of the product. The knowledge on the microbial diversity associated with GP has been the subject, in recent years, of several studies aimed at understanding its composition and characteristics in order, on the one hand, to improve its technological performances and, on the other hand, to indirectly enhance the nutritional quality of the product. This review aims to briefly illustrate the main available knowledge on the composition and properties of the GP microbiota, inferred from dozens of studies carried out by both classical microbiology techniques and metagenomic analysis. The paper will essentially, but not exclusively, be focused on the lactic acid bacteria (LAB) derived from starter (SLAB) and the non-starter bacteria, both lactic (NSLAB) and non-lactic, of milk origin.
2
Parente, Eugenio, Angela Guidone, Attilio Matera, Francesca De Filippis, Gianluigi Mauriello, and Annamaria Ricciardi. "Microbial community dynamics in thermophilic undefined milk starter cultures." International Journal of Food Microbiology 217 (January 2016): 59–67. http://dx.doi.org/10.1016/j.ijfoodmicro.2015.10.014.
3
Smid, Eddy J., Oylum Erkus, Maciej Spus, Judith CM Wolkers-Rooijackers, Svetlana Alexeeva, and Michiel Kleerebezem. "Functional implications of the microbial community structure of undefined mesophilic starter cultures." Microbial Cell Factories 13, Suppl 1 (2014): S2. http://dx.doi.org/10.1186/1475-2859-13-s1-s2.
4
Frantzen, Cyril Alexander, and Helge Holo. "Unprecedented Diversity of Lactococcal Group 936 Bacteriophages Revealed by Amplicon Sequencing of the Portal Protein Gene." Viruses 11, no. 5 (May 16, 2019): 443. http://dx.doi.org/10.3390/v11050443.
Abstract:
Lactococcus lactis is one of the most important bacteria in dairy fermentations, being used in the production of cheese and buttermilk. The processes are vulnerable to phage attacks, and undefined mixtures of lactococcal strains are often used to reduce the risk of bacteriophage caused fermentation failure. Other preventive measures include culture rotation to prevent phage build-up and phage monitoring. Phage diversity, rather than quantity, is the largest threat to fermentations using undefined mixed starter cultures. We have developed a method for culture independent diversity analysis of lytic bacteriophages of the 936 group, the phages most commonly found in dairies. Using, as a target, a highly variable region of the portal protein gene, we demonstrate an unprecedented diversity and the presence of new 936 phages in samples taken from cheese production. The method should be useful to the dairy industry and starter culture manufacturers in their efforts to reduce phage problems.
5
MORZEL, MARTINE, NICOLINE G. FRANSEN, and ELKE K. ARENDT. "Defined Starter Cultures used for Fermentation of Salmon Fillets." Journal of Food Science 62, no. 6 (November 1997): 1214–18. http://dx.doi.org/10.1111/j.1365-2621.1997.tb12247.x.
6
STAVRIC, S., and J. Y. D'AOUST. "Undefined and Defined Bacterial Preparations for the Competitive Exclusion of Salmonella in Poultry - A Review." Journal of Food Protection 56, no. 2 (February 1, 1993): 173–80. http://dx.doi.org/10.4315/0362-028x-56.2.173.
Abstract:
During the past two decades, there have been many studies on the efficacy of competitive exclusion for the control of Salmonella in poultry. Undefined preparations of cultured fecal or cecal microflora generally reduce the prevalence of infected chicks upon challenge with a standard dose of Salmonella under laboratory conditions; in contrast, results under field conditions are more variable. The protective capacity of undefined cultures can be affected by several factors including the source of microflora, method for protective culture administration, presence of poultry feed additives, in-laboratory or natural environmental challenge, and hygienic practices on the farm. The formulation of effective defined cultures is most difficult because of insufficient knowledge on the underlying protective mechanism(s) and interactions between gut microflora. Defined cultures are less effective than undefined cultures under laboratory conditions and afford little protection against natural Salmonella challenge; their potency decreases upon storage and manipulation of single or mixtures of defined culture isolates.
7
Carvalho, Erich H., Angélica S. Mendes, Sabrina E. Takahashi, Rosângela A. B. Assumpção, Douglas V. Bonamigo, Daniel Müller, and Rosana R. Sikorski. "Defined and undefined commercial probiotics cultures in the prevention of Salmonella Enteritidis in broilers." Pesquisa Veterinária Brasileira 38, no. 2 (February 2018): 271–76. http://dx.doi.org/10.1590/1678-5150-pvb-4860.
Abstract:
ABSTRACT: This study aimed to evaluate the efficacy of probiotics from different formations, defined and undefined cultures, applied in the control of Salmonella Enteritidis in broilers, identifying the compositions and states for which the probiotics are more effective. For that, 390 broilers were inoculated orally with 1.00 ml of Salmonella Enteritidis at a concentration of 1.2x109 CFU (Colony Forming Units). The experimental design used was randomized blocks with 5 treatments and 6 replications, totaling 30 boxes with 13 birds/box (13 birds/m2). The treatments were provided via drinking water 1 hour after inoculation, keeping a daily treatment of 12 hours with probiotics, for 3 consecutive days (birds at 1, 2 and 3 days of age). In general, the five treatments conducted were: T1 - Control without probiotic, T2 - Probiotic A (defined culture - lyophilized form, strain 7), T3 - Probiotic B (defined culture - lyophilized form, strain 11), T4 - Probiotic C (undefined culture liquid form), T5 - Probiotic D (undefined culture - liquid form). After treatments, performance was evaluated through average body weight, feed conversion and mortality counting. Microbiological analysis and Salmonella isolation were performed using MPN (Most Probable Number) and selective enrichment technique methods, respectively. Samples of ileum and liver pool, cecal tonsils, cecum, heart and spleen pool were collected at 5 and 31 days of age. No differences were observed on growth performance and isolation of Salmonella Enteritidis (p≥0.05). All probiotics applied were effective on reducing Salmonella Enteritidis colonization in the ileum, cecal tonsils, and cecum at 5 days of life. Probiotics T2 and T5 has shown effectiveness in reducing colonization at 31 days, being considered the most efficient on Salmonella Enteritidis control, for the intestines segments evaluated. It was not possible to affirm which probiotics formation, defined or undefined, is more efficient for Salmonella Enteritidis control.
8
García-Díez, Juan, and Cristina Saraiva. "Use of Starter Cultures in Foods from Animal Origin to Improve Their Safety." International Journal of Environmental Research and Public Health 18, no. 5 (March 4, 2021): 2544. http://dx.doi.org/10.3390/ijerph18052544.
Abstract:
Starter cultures can be defined as preparations with a large number of cells that include a single type or a mixture of two or more microorganisms that are added to foods in order to take advantage of the compounds or products derived from their metabolism or enzymatic activity. In foods from animal origin, starter cultures are widely used in the dairy industry for cheese, yogurt and other fermented dairy products, in the meat industry, mainly for sausage manufacture, and in the fishery industry for fermented fish products. Usually, microorganisms selected as starter culture are isolated from the native microbiota of traditional products since they are well adapted to the environmental conditions of food processing and are responsible to confer specific appearance, texture, aroma and flavour characteristics. The main function of starter cultures used in food from animal origin, mainly represented by lactic acid bacteria, consists in the rapid production of lactic acid, which causes a reduction in pH, inhibiting the growth of pathogenic and spoilage microorganisms, increasing the shelf-life of fermented foods. Also, production of other metabolites (e.g., lactic acid, acetic acid, propionic acid, benzoic acid, hydrogen peroxide or bacteriocins) improves the safety of foods. Since starter cultures have become the predominant microbiota, it allows food processors to control the fermentation processes, excluding the undesirable flora and decreasing hygienic and manufacturing risks due to deficiencies of microbial origin. Also, stater cultures play an important role in the chemical safety of fermented foods by reduction of biogenic amine and polycyclic aromatic hydrocarbons contents. The present review discusses how starter cultures contribute to improve the microbiological and chemical safety in products of animal origin, namely meat, dairy and fishery products.
9
Bockelmann, Wilhelm. "Development of defined surface starter cultures for the ripening of smear cheeses." International Dairy Journal 12, no. 2-3 (January 2002): 123–31. http://dx.doi.org/10.1016/s0958-6946(01)00152-2.
10
Hati, Subrota, Surajit Mandal, and J. Prajapati. "Novel Starters for Value Added Fermented Dairy Products." Current Research in Nutrition and Food Science Journal 1, no. 1 (August 27, 2013): 83–91. http://dx.doi.org/10.12944/crnfsj.1.1.09.
Abstract:
Starter cultures are those microorganisms (bacteria, yeasts, and molds or their combinations) that initiate and carry out the desired fermentation essential in manufacturing cheese and fermented dairy products such as Dahi, Lassi, Yogurt, Sour cream, Kefir, and Koumiss amongst others. Starter culture is defined as “an active microbial preparation, deliberately added to initiate desirable changes during preparation of fermented products”. Starter cultures have a multifunctional role in dairy fermentations. The production of lactic acid by fermenting lactose is the major role of dairy starters. The acid is responsible for development of characteristic body and texture of the fermented milk products, contributes to the overall flavour of the products, and enhances preservation. Beyond the horizons of their conventional role in acid, flavour and texture development, they are being looked up on as burgeoning “cell factories” for production of host of functional biomolecules and food ingredients such as biothickeners, bacteriocins, vitamins, bioactive peptides and amino acids.
11
Cvetkovic, Dragoljub, and Sinisa Markov. "Preparation of kombucha from winter savory (Satureja Montana L.) in the laboratory bioreactor." Acta Periodica Technologica, no. 36 (2005): 187–96. http://dx.doi.org/10.2298/apt0536187c.
Abstract:
The possibility of obtaining kombucha from winter savory tea has been tested in the laboratory bioreactor by applying starter cultures and traditional way of inoculation. On the basis of the obtained results, it can be concluded that applying the inoculating method with the beverage from the previous process of biotransformation yielded kombucha beverage (capacity 15 I) from winter savory tea in the laboratory bioreactor. The application of defined starter culture from the isolate of yeast and acetic acid bacteria of local tea in the glass jar (capacity 5 I) gave 3 litres of kombucha beverage, which is acceptable according to the basic parameters and sensory characteristics. However, the application of the same starter culture in the laboratory bioreactor did not result in synchronized activity of yeast and bacteria.
12
Zakharova, Lyudmila, and Marina Gorbunchikova. "A New Synbiotic Fermented Dairy Product: Technological Production Features." Food Processing: Techniques and Technology 51, no. 1 (March 25, 2021): 17–28. http://dx.doi.org/10.21603/2074-9414-2021-1-17-28.
Abstract:
Introduction. Many strains used in dairy industry are antagonists of harmful microflora. Logically, a successful combination of several cultures can enhance the bactericidal effect. The present research objective was to develop a fermented milk drink using a prebiotic to stimulate a multicomponent starter culture.
Study objects and methods. The research featured pure strains of Bifidobacterium bifidum strain No. 791 and Lactobacillus acidophilus (VZ-AP), as well as Bio-fi Pro WR 400 beet fiber. The study involved standard and conventional research methods.
Results and discussion. The first stage defined the optimal ratios of B. bifidum and L. acidophilus for a two-component starter culture, as well as the optimal production method and their antibiotic activity. The second stage featured the functional and technological properties of the prebiotic beet fiber and its effect on the development of microorganisms in the starter. The study resulted in the main production parameters and a technological scheme for the production of fermented dairy product.
Conclusion. The paper introduces a new technology for production of a functional fermented milk product fortified with probiotics and prebiotics, as well as approved technical documentation. The new functional fermented dairy product was based on a starter
culture that combined a liquid concentrate of B. bifidum strain No. 791 and a starter culture of L. acidophilus (VZ-AP). The optimal ratio of microbial cultures was 5:1, respectively. The starter strain proved to have a high antibiotic activity. Prebiotic beet fiber Bio-fi Pro WR 400 could be recommended as a product stabilizer at the optimal amount of 0.7% by weight of standardized milk.
13
Basappa, S. C., D. Somashekar, Renu Agrawal, K. Suma, and K. Bharathi. "Nutritional composition of fermentedragi(chhang) byphaband defined starter cultures as compared to unfermentedragi(Eleucine coracanaG.)." International Journal of Food Sciences and Nutrition 48, no. 5 (January 1997): 313–19. http://dx.doi.org/10.3109/09637489709028577.
14
Nambou, Komi, Caixia Gao, Fangfang Zhou, Benheng Guo, Lianzhong Ai, and Zheng-Jun Wu. "A novel approach of direct formulation of defined starter cultures for different kefir-like beverage production." International Dairy Journal 34, no. 2 (February 2014): 237–46. http://dx.doi.org/10.1016/j.idairyj.2013.03.012.
15
Кригер, Ольга, Olga Kriger, Светлана Носкова, and Svetlana Noskova. "Properties of Lactic Acid Microorganisms: Long-Term Preservation Methods." Food Processing: Techniques and Technology 48, no. 4 (February 13, 2019): 30–38. http://dx.doi.org/10.21603/2074-9414-2018-4-30-38.
Abstract:
Among the relevant studies on lactic acid bacteria there are projects devoted to the multienzyme complexes of starter cultures, new competitive bacterial concentrates and their use in fermented functional milk products. In fermented milk production, the process of albuminolysis has a significant impact on the consistency, taste, and smell of the product. Therefore, lactic acid bacteria with high proteolytic properties are of the greatest interest for fermented milk industry. The present research features long- term methods for preservation of the properties of lactic acid microorganisms. The experiment defined the regime parameters of combined starter lyophilisation. The results prove that fermented milk production requires high-quality starter strains. The authors developed a long-term method for preservation of properties of particular strains of lactic acid microorganisms. The method presupposes freeze-drying with the following parameters: freezing temperature – minus 25°C in a protective 5%-glycerol medium (90 minutes); the drying temperature – 30°C (6 hours); refrigerating load – 5.45 kW/m²; residual pressure – 0.6‒0.8 kPa, bed depth – 2 mm. The authors also developed the necessary documentation (No. 9225-096-02054145-2013), procedures, and formula of the fermented milk product with a combined direct application starter.
16
Prknová, H. "The use of silica sand in micropropagation of woods." Journal of Forest Science 53, No. 2 (January 7, 2008): 88–92. http://dx.doi.org/10.17221/2138-jfs.
Abstract:
Cultures <i>in vitro</i> made in agar are rather precarious, because gel strength varies both with the medium formula used and the source and grade of agar. Any solidifying agent (like for example agar) should be strong enough to support cultivated plantlets, yet liquid enough to allow the nutrients and drossy products from plants through the medium. It should also be a chemically inert material. Agar, especially in acid solutions, is an undefined constituent of culture media, namely in the mentioned properties. Silica sand, used in cultures of herbs up to the present time, is applicable also in cultures of <i>Sorbus sudetica</i>. The required acid medium is exactly defined if sand is substituted for agar. Similar cultures of wood species, including conifers, will be realized in future research.
17
Bojanic-Rasovic, Mirjana, Sigrid Mayrhofer, Mary Ochome, Erna Ajanovic, Marija Zunabovic, Aleksandra Martinovic, and Konrad Domig. "Diversity of lactic acid bacteria isolated from traditional Montenegrin dairy products." Genetika 50, no. 2 (2018): 465–82. http://dx.doi.org/10.2298/gensr1802465b.
Abstract:
Traditional production of fermented dairy products in Montenegro is carried out without adding defined starter cultures. This way of production involves lactic acid bacteria (LAB) that are normally present in the raw milk and production environment. This autochthonous ("wild") fermentation microbiota represents a reservoir of unknown strains. In order to study the LAB diversity, 25 indigenous dairy products in Montenegro have been tested. Isolation was performed on microbial media M17 and MRS agar with or without supplementations under aerobic and anaerobic conditions at temperatures of 30?C, 37 ?C and 44?C. Identification of these isolates at species level was done by species-specific PCR and gene regions sequencing of representatives of each RAPD-cluster. RAPD-PCR was used to characterize the isolates at strain level. Nine Lactobacillus species, five Leuconostoc species, four Enterococcus species as well as strains of the species Lactococcus lactis, Pediococcus pentosaceus and Streptococcus thermophilus were detected. It can be concluded that a rich lactic acid bacteria diversity existed in the analyzed Montenegrin dairy products. Further examination of the isolates could lead to the development of autochthonous starter cultures that would contribute to a product that is characteristic for the geographical area and to which the local population is accustomed.
18
John, Gernot T., Detlef Goelling, Ingo Klimant, Holger Schneider, and Elmar Heinzle. "pH-Sensing 96-well microtitre plates for the characterization of acid production by dairy starter cultures." Journal of Dairy Research 70, no. 3 (July 21, 2003): 327–33. http://dx.doi.org/10.1017/s0022029903006344.
Abstract:
A new method for characterization of acid production by dairy starter cultures is presented. Microplates with integrated optical pH sensors are developed. Two fluorophores, a pH-sensitive and a pH-insensitive one are immobilised at the bottom of a polystyrene 96-well microtitre plate. The pH-insensitive fluorophore serves as an internal reference and makes calibration unnecessary. The sensor measures pH accurately in optically well-defined media. Particles and fluorophores contained in the bulk medium disturbed the measurements. Despite these disturbances it was possible to clearly sense differences in inoculum type and in inoculum sizes of cultures of Lactococcus lactis and of Streptococcus thermophilus at 30 and 37°C. Besides a pH-related signal there is information about other changes during milk fermentation. The cultivation results were compared with those from the established CINAC-method. From this comparison it can be concluded that the new method can be used reliably to characterize particularly a large number of strains for screening purposes but also for quality control.
19
Nejati, Fatemeh, Stefan Junne, and Peter Neubauer. "A Big World in Small Grain: A Review of Natural Milk Kefir Starters." Microorganisms 8, no. 2 (January 30, 2020): 192. http://dx.doi.org/10.3390/microorganisms8020192.
Abstract:
Milk kefir is a traditional fermented milk product whose consumption is becoming increasingly popular. The natural starter for kefir production is kefir grain, which consists of various bacterial and yeast species. At the industrial scale, however, kefir grains are rarely used due to their slow growth, complex application, bad reproducibility and high costs. Instead, mixtures of defined lactic acid bacteria and sometimes yeasts are applied, which alter sensory and functional properties compared to natural grain-based milk kefir. In order to be able to mimic natural starter cultures for authentic kefir production, it is a prerequisite to gain deep knowledge about the nature of kefir grains, its microbial composition, morphologic structure, composition of strains on grains and the impact of environmental parameters on kefir grain characteristics. In addition, it is very important to deeply investigate the numerous multi-dimensional interactions among different species, which play important roles on the formation and the functionality of grains.
20
Hayek, Saeed A., Rabin Gyawali, Sulaiman O. Aljaloud, Albert Krastanov, and Salam A. Ibrahim. "Cultivation media for lactic acid bacteria used in dairy products." Journal of Dairy Research 86, no. 4 (November 2019): 490–502. http://dx.doi.org/10.1017/s002202991900075x.
Abstract:
AbstractThis review aims to familiarize the reader with research efforts on the cultivation media of lactic acid bacteria (LAB). We have also included a brief discussion on standard ingredients used in LAB media and chemically defined media as related to bacterial growth requirements. Recent research has focused on modifying standard media for the enumeration, differentiation, isolation, and identification of starter cultures and probiotics. Even though large numbers of these media have been developed to serve dairy microbial control, they have failed to provide consistent results. The research consequently points to the need to develop a reliable lactobacilli growth medium for the dairy industry.
21
Frantzen, Cyril, Hans Petter Kleppen, and Helge Holo. "Use of M17 and a milk-based medium enables isolation of two distinct and diverse populations of Lactococcus lactis strains from undefined mesophilic starter cultures." International Dairy Journal 53 (February 2016): 45–50. http://dx.doi.org/10.1016/j.idairyj.2015.09.005.
22
Berhe, Tesfemariam, Richard Ipsen, Eyassu Seifu, Mohamed Y. Kurtu, Angelina Fugl, and Egon Bech Hansen. "Metagenomic analysis of bacterial community composition in Dhanaan: Ethiopian traditional fermented camel milk." FEMS Microbiology Letters 366, Supplement_1 (June 10, 2019): i127—i132. http://dx.doi.org/10.1093/femsle/fnz128s.
Abstract:
ABSTRACT This study was conducted to evaluate the safety and bacterial profile of Dhanaan (Ethiopian traditional fermented camel milk). The composition of the microbial community in Dhanaan samples was analysed by a metagenomic approach of 16S rRNA gene amplicon sequencing. Metagenomic profiling identified 87 different bacterial microorganisms (OTUs) in six samples analysed. Although the Dhanaan samples contained various lactic acid bacteria (LAB), they also all contained undesirable microorganisms in large proportions. The following LAB genera were identified: Streptococcus, Lactococcus and Weissella. One Streptococcus species represented by OTU-1 (operational taxonomic unit) was found in all Dhanaan samples and the dominating species in four out of six samples. This common isolate was found to be closely related to S. lutetiensis and S. infantarius. Undesirable microorganisms from genera such as Escherichia, Klebsiella, Enterobacter, Acinetobacter and Clostridium were, however, also frequent, or even dominant in Dhanaan samples. Thus, this calls for a change in the Dahnaan manufacturing practice to an improved and safer production system. Starter cultures suitable for Dhanaan production might be developed from the Streptococcus, Weissella and Lactococcus microorganisms identified in this study. However, further safety evaluation and technological characterization need to be conducted on strains defined by OTU-1, OTU-2, OTU-3, OTU-8 and OTU-35 before they can be used as food grade starter cultures.
23
Dias, Igor, Marta Laranjo, Maria Eduarda Potes, Ana Cristina Agulheiro-Santos, Sara Ricardo-Rodrigues, Ana Rita Fialho, Joana Véstia, Maria João Fraqueza, Margarida Oliveira, and Miguel Elias. "Autochthonous Starter Cultures Are Able to Reduce Biogenic Amines in a Traditional Portuguese Smoked Fermented Sausage." Microorganisms 8, no. 5 (May 8, 2020): 686. http://dx.doi.org/10.3390/microorganisms8050686.
Abstract:
Traditional smoked fermented sausages are highly appreciated in Portugal and are mostly manufactured according to traditional procedures. The aim of the present work was to evaluate the effect of autochthonous starter cultures on the safety and quality of a smoked fermented sausage, Painho da Beira Baixa (PBB), preserving its sensory quality. Physicochemical parameters, namely pH and water activity (aW), microbiological parameters, biogenic amines, colour, texture profile and sensory attributes were assessed. Different starters were selected based on our previous work. Staphylococcus equorum S2M7, Staphylococcus xylosus CECT7057, Lactobacillus sakei CV3C2, Lactobacillus sakei CECT7056 and a yeast strain (2RB4) were co-inoculated in meat batters at defined concentrations. Starters had a significant effect on the reduction of pH. Enterobacteria and Listeria monocytogenes were not detected in inoculated end-product sausages. Moreover, sausages inoculated with S. equorum S2M7/L. sakei CV3C2/yeast 2RB4 showed a significant reduction in the total content of biogenic amines. No significant differences between treatments were observed for colour and texture parameters, except for adhesiveness. The studied starters did not compromise the sensory characteristics of PBB. To our knowledge, this is the first comprehensive study on the quality and safety of this type of smoked fermented sausage from the central region of Portugal.
24
Gomez, M. J., E. Rodriguez, P. Gaya, M. Nuñez, and M. Medina. "Characteristics of Manchego Cheese Manufactured from Raw and Pasteurized Ovine Milk and with Defined-Strain or Commercial Mixed-Strain Starter Cultures." Journal of Dairy Science 82, no. 11 (November 1999): 2300–2307. http://dx.doi.org/10.3168/jds.s0022-0302(99)75478-0.
25
Barbieri, Federica, Luca Laghi, Chiara Montanari, Qiuyu Lan, Alessia Levante, Fausto Gardini, and Giulia Tabanelli. "Insights into the Metabolomic Diversity of Latilactobacillus sakei." Foods 11, no. 3 (February 6, 2022): 477. http://dx.doi.org/10.3390/foods11030477.
Abstract:
Latilactobacillus sakei (L. sakei), widely used as a starter culture in fermented sausages, is a species adapted to meat environments. Its ability to survive for a long time in such products is due to the exploitation of different metabolic pathways to gain energy (hexose and pentose sugar fermentation, amino acids catabolism, etc.). Since L. sakei demonstrates high phenotypic and metabolic strain biodiversity, in this work, a metabolomic approach was used to compare five strains of different origins. They were cultivated in a defined medium with glucose or ribose at two concentrations, and analyzed through nuclear magnetic resonance (1H-NMR) spectroscopy to monitor amino acid consumptions and accumulation of organic acids and aroma compounds. The results showed that all the strains were able to use arginine, especially when cultivated with ribose, while serine was consumed mainly in the presence of glucose. Aroma compounds (i.e., diacetyl and acetoin) were mainly accumulated in samples with ribose. These aspects are relevant for starter cultures selection, to confer specific features to fermented sausages, and to optimize the fermentations. Moreover, the use of 1H-NMR allowed the fast identification of different classes of compounds (without derivatization or extraction procedures), providing a powerful tool to increase the knowledge of the metabolic diversity of L. sakei.
26
Burdychová, Radka, and V. Dohnal. "Screening of probiotic cultures intended for processing of fermented foods for their ability to produce biogenic amines." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 56, no. 1 (2008): 25–30. http://dx.doi.org/10.11118/actaun200856010025.
Abstract:
The contemporary trend is using probiotic cultures in fermented food production. They can be used as starter cultures and for their positive effect on human health. Probiotics are defined as living microorganisms present in food which consumed in adequate amounts affects positively the intestinal microflora’s composition and balance and thus human health itself. Cultures of these bacteria have to be of human origin and be able to survive the passage through the gastrointestinal tract. They also have to be able to multiply on the site of action (in intestine) and must not be toxic or pathogenic. Unfortunately, even some probiotic cultures can be counted among potential producers of biogenic amines, so their testing for the presence of biogenic amines is necessary (BURDYCHOVÁ, 2007).The aim of this study was screening of 26 types of bacterial cultures (SACCO, Italy) as probiotic cultures for their ability to produce biogenic amines tyramine and histamine. Cultivation in decarboxylating medium (BOVER-CID and HOLZAPFEL, 1999), HPLC descibed by BURDYCHOVÁ and DOHNAL (2007), and PCR detection of genes coding enzymes tyrosindecarboxylase and histidindecarboxylase, participating in formation of biogenic amines (COTON et al., 2004), were used as the screening methods. 19 strains of Lactobacillus spp., 3 strains of Bifidobacterium spp., 2 strains of Pediococcus spp. and 2 strains of Enterococcus spp. were examined by the methods mentioned above. The tyramine production was detected at 8 strains of Lactobacillus spp., 3 strains of Bifidobacterium spp. and 2 strains of Enterococcus spp., whereas no tested cultures were found to be able to produce histamine.The strains at which production of biogenic amines tyramine and histamine wasn’t detected are suitable for fermented food processing. When the strains at which production of tyramine was demonstrated were used in food processing, a control of concentration of this biogenic amine in final product is highly recommended.
27
WATERS, SINÉAD M., RICHARD A. MURPHY, and RONAN F. G. POWER. "Assessment of the Effects of Nurmi-Type Cultures and a Defined Probiotic Preparation on a Salmonella Typhimurium 29E Challenge In Vivo." Journal of Food Protection 68, no. 6 (June 1, 2005): 1222–27. http://dx.doi.org/10.4315/0362-028x-68.6.1222.
Abstract:
The effects of treatment with an undefined commercial Nurmi-type culture (NTC), cultured cecal contents, and a dual-strain probiotic, containing Enterococcus faecalis and Pediococcus pentosaceus, on Salmonella Typhimurium colonization were evaluated in a specific-pathogen-free bird model. Two sets of trials were performed, and each study was arranged as a randomized complete block design with three treatments. Treatments consisted of (i) control, (ii) commercial NTC, and (iii) cultured cecal contents in the first set of trials and (i) control, (ii) defined probiotic, and (iii) cultured cecal contents in the second set. On day 1, birds were administered 1.2 × 107 CFU of the appropriate treatment by oral gavage. On day 3, all birds were challenged with 1 × 106 CFU of Salmonella Typhimurium 29E (nalidixic acid resistant). Chicks were asphyxiated with argon gas on day 10, and ceca were aseptically removed. Salmonella Typhimurium counts (CFU per milliliter of cecal contents) were determined on brilliant green agar containing 30 mg of nalidixic acid per liter, and CFU counts were log transformed prior to analysis. Cecal pH and volatile fatty acid concentrations were also determined. Data were analyzed by one-way analysis of variance, and means were compared by Tukey's pairwise analysis. Commercial NTC and cultured cecal contents treatments resulted in a significant decrease (P ≤ 0.05) in Salmonella Typhimurium 29E colonization, with the NTC offering a higher level of protection. In the second set of trials, the defined probiotic tended to reduce colonization by Salmonella Typhimurium (P = 0.07), while chicks treated with cultured cecal contents displayed a significant decrease (P = 0.03) when compared to the negative control. No significant change was observed in cecal pH or in acetate and propionate concentrations; however, a significant increase in butyrate concentrations in both the cultured cecal contents and defined probiotic treatment groups was observed when compared to the control birds. These observations suggest that defined cultures are less effective Salmonella control agents than are preparations generated from the complete cecal microflora.
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LÜDIN, PETRA, ALEXANDRA ROETSCHI, DANIEL WÜTHRICH, RÉMY BRUGGMANN, HÉLÈNE BERTHOUD, and NOAM SHANI. "Update on Tetracycline Susceptibility of Pediococcus acidilactici Based on Strains Isolated from Swiss Cheese and Whey." Journal of Food Protection 81, no. 10 (August 31, 2018): 1582–89. http://dx.doi.org/10.4315/0362-028x.jfp-18-160.
Abstract:
ABSTRACTBacterial strains used as starter cultures in the production of fermented foods may act as reservoirs for antibiotic resistance (AbR) genes. To avoid the introduction of such genes into the food chain, the presence of acquired AbR in bacterial strains added to food must be tested. Standard protocols and microbiological cut-off values have been defined to provide practitioners with a basis for evaluating whether their bacterial isolates harbor an acquired resistance to a given antibiotic. Here, we tested the AbR of 24 strains of Pediococcus acidilactici by using the standard protocol and microbiological cut-off values recommended by the European Food Safety Authority. Phenotypic data were complemented by searching for known AbR genes using an in silico analysis of whole genomes. The majority (54.2%) of the strains were able to grow at a tetracycline concentration above the defined cut-off, even though only one strain carried a known tetracycline resistance gene, tetM. The same strain also carried the AbR gene of an erythromycin resistance methylase, ermA, and displayed resistance toward clindamycin and erythromycin. Our results bolster the scarce data on the sensitivity of P. acidilactici to tetracycline and suggest that the microbiological cut-off recommended by the European Food Safety Authority for this antibiotic should be amended.
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Hill, Daragh, Ivan Sugrue, Elke Arendt, Colin Hill, Catherine Stanton, and R. Paul Ross. "Recent advances in microbial fermentation for dairy and health." F1000Research 6 (May 26, 2017): 751. http://dx.doi.org/10.12688/f1000research.10896.1.
Abstract:
Microbial fermentation has been used historically for the preservation of foods, the health benefits of which have since come to light. Early dairy fermentations depended on the spontaneous activity of the indigenous microbiota of the milk. Modern fermentations rely on defined starter cultures with desirable characteristics to ensure consistency and commercial viability. The selection of defined starters depends on specific phenotypes that benefit the product by guaranteeing shelf life and ensuring safety, texture, and flavour. Lactic acid bacteria can produce a number of bioactive metabolites during fermentation, such as bacteriocins, biogenic amines, exopolysaccharides, and proteolytically released peptides, among others. Prebiotics are added to food fermentations to improve the performance of probiotics. It has also been found that prebiotics fermented in the gut can have benefits that go beyond helping probiotic growth. Studies are now looking at how the fermentation of prebiotics such as fructo-oligosaccharides can help in the prevention of diseases such as osteoporosis, obesity, and colorectal cancer. The potential to prevent or even treat disease through the fermentation of food is a medically and commercially attractive goal and is showing increasing promise. However, the stringent regulation of probiotics is beginning to detrimentally affect the field and limit their application.
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Shani, Noam, Simone Oberhaensli, Hélène Berthoud, Remo S. Schmidt, and Hans-Peter Bachmann. "Antimicrobial Susceptibility of Lactobacillus delbrueckii subsp. lactis from Milk Products and Other Habitats." Foods 10, no. 12 (December 18, 2021): 3145. http://dx.doi.org/10.3390/foods10123145.
Abstract:
As components of many cheese starter cultures, strains of Lactobacillus delbrueckii subsp. lactis (LDL) must be tested for their antimicrobial susceptibility to avoid the potential horizontal transfer of antibiotic resistance (ABR) determinants in the human body or in the environment. To this end, a phenotypic test, as well as a screening for antibiotic resistance genes (ARGs) in genome sequences, is commonly performed. Historically, microbiological cutoffs (MCs), which are used to classify strains as either ‘sensitive’ or ‘resistant’ based on the minimal inhibitory concentrations (MICs) of a range of clinically-relevant antibiotics, have been defined for the whole group of the obligate homofermentative lactobacilli, which includes LDL among many other species. This often leads to inaccuracies in the appreciation of the ABR status of tested LDL strains and to false positive results. To define more accurate MCs for LDL, we analyzed the MIC profiles of strains originating from various habitats by using the broth microdilution method. These strains’ genomes were sequenced and used to complement our analysis involving a search for ARGs, as well as to assess the phylogenetic proximity between strains. Of LDL strains, 52.1% displayed MICs that were higher than the defined MCs for kanamycin, 9.9% for chloramphenicol, and 5.6% for tetracycline, but no ARG was conclusively detected. On the other hand, all strains displayed MICs below the defined MCs for ampicillin, gentamycin, erythromycin, and clindamycin. Considering our results, we propose the adaptation of the MCs for six of the tested clinically-relevant antibiotics to improve the accuracy of phenotypic antibiotic testing.
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Rowley, SD, C. Brashem-Stein, R. Andrews, and ID Bernstein. "Hematopoietic precursors resistant to treatment with 4- hydroperoxycyclophosphamide: requirement for an interaction with marrow stroma in addition to hematopoietic growth factors for maximal generation of colony-forming activity." Blood 82, no. 1 (July 1, 1993): 60–65. http://dx.doi.org/10.1182/blood.v82.1.60.bloodjournal82160.
Abstract:
We tested the ability of CD34+lin- precursor cells isolated from marrow after treatment with 4-hydroperoxycyclophosphamide (4HC) to generate colony-forming cells (CFC). In liquid cultures, recombinant human stem cell factor (SCF), in combination with interleukin-1 (IL-1), IL-3, IL- 6, granulocyte-macrophage colony-stimulating factor, or granulocyte colony-stimulating factor caused untreated, but not 4HC-treated, CD34+lin- cells to form CFC. However, generation of CFC from CD34+lin- cells treated with 60 micrograms/mL of 4HC was possible in the presence of an irradiated allogeneic stromal cell layer. This generation was increased when combinations of hematopoietic growth factors including SCF and IL-3 were added. Maximal generation of CFC was seen after 11 to 21 days of culture. At that time, generation of CFC from CD34+lin- 4HC- treated cells equalled that from untreated cells. The phenotype of these 4HC-resistant CD34+lin- precursors was also further defined as CD38-. These studies show that the generation of CFC from the 4HC- resistant, highly immature population of CD34+lin- cells requires an as yet undefined interaction with marrow stroma in addition to known hematopoietic growth factors.
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Kim, Eun J., Ami P. Raval, and Miguel A. Perez-Pinzon. "Preconditioning Mediated by Sublethal Oxygen—Glucose Deprivation-Induced Cyclooxygenase-2 Expression via the Signal Transducers and Activators of Transcription 3 Phosphorylation." Journal of Cerebral Blood Flow & Metabolism 28, no. 7 (April 9, 2008): 1329–40. http://dx.doi.org/10.1038/jcbfm.2008.26.
Abstract:
The signal transducers and activators of transcription (STATs) were found to be essential for cardioprotection. However, their role in preconditioning (PC) neuroprotection remains undefined. Previously, our studies showed that PC mediated a signaling cascade that involves activation of epsilon protein kinase C (εPKC), extracellular signal-regulated kinase (ERK1/2), and cyclooxygenase-2 (COX-2) pathways. However, the intermediate pathway by which ERK1/2 activates COX-2 was not defined. In this study, we investigated whether the PC-induced signaling pathway requires phosphorylation of STAT isoforms for COX-2 expression. To mimic PC or lethal ischemia, mixed cortical neuron/astrocyte cell cultures were subjected to 1 and/or 4 h of oxygen—glucose deprivation (OGD), respectively. The results indicated serine phosphorylation of STAT3 after PC or εPKC activation. Inhibition of either εPKC or ERK1/2 activation abolished PC-induced serine phosphorylation of STAT3. Additionally, inhibition of STAT3 prevented PC-induced COX-2 expression and neuroprotection against OGD. Therefore, our findings suggest that PC signaling cascade involves STAT3 activation after εPKC and ERK1/2 activation. Finally, we show that STAT3 activation mediates COX-2 expression and ischemic tolerance.
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Nyhan, Laura M., Kieran M. Lynch, Aylin W. Sahin, and Elke K. Arendt. "Advances in Kombucha Tea Fermentation: A Review." Applied Microbiology 2, no. 1 (January 15, 2022): 73–101. http://dx.doi.org/10.3390/applmicrobiol2010005.
Abstract:
Kombucha is a carbonated, slightly acidic beverage traditionally produced by the fermentation of sweetened tea by a symbiotic culture of bacteria and yeast (SCOBY). The microbial community of kombucha is a complex one, whose dynamics are still not fully understood; however, the emergence of culture-independent techniques has allowed a more comprehensive insight into kombucha microbiota. In recent times, advancements have been made towards the optimisation of the fermentation process, including the use of alternative substrates, defined starter cultures and the modification of fermentation parameters, with the aim of producing an innovative beverage that is improved in terms of its physiochemical, sensory and bioactive properties. The global kombucha market is rapidly increasing, with the rising popularity of the tea attributed in part to its purported health benefits, despite the lack of research in human subjects to substantiate such claims. Accordingly, the incidence of kombucha home-brewing has increased, meaning there is a requirement for individuals to recognise the potential hazards associated with fermentation and the relevant preventative measures to be undertaken to ensure the safe preparation of kombucha. The aim of this review is to provide an update regarding the current knowledge of kombucha production, microbiology, safety and marketing.
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Li, Yin, Jeroen Hugenholtz, Tjakko Abee, and Douwe Molenaar. "Glutathione Protects Lactococcus lactis against Oxidative Stress." Applied and Environmental Microbiology 69, no. 10 (October 2003): 5739–45. http://dx.doi.org/10.1128/aem.69.10.5739-5745.2003.
Abstract:
ABSTRACT Glutathione was found in several dairy Lactococcus lactis strains grown in M17 medium. None of these strains was able to synthesize glutathione. In chemically defined medium, L. lactis subsp. cremoris strain SK11 was able to accumulate up to ∼60 mM glutathione when this compound was added to the medium. Stationary-phase cells of strain SK11 grown in chemically defined medium supplemented with glutathione showed significantly increased resistance (up to fivefold increased resistance) to treatment with H2O2 compared to the resistance of cells without intracellular glutathione. The resistance to H2O2 treatment was found to be dependent on the accumulation of glutathione in 16 strains of L. lactis tested. We propose that by taking up glutathione, L. lactis might activate a glutathione-glutathione peroxidase-glutathione reductase system in stationary-phase cells, which catalyzes the reduction of H2O2. Glutathione reductase, which reduces oxidized glutathione, was detectable in most strains of L. lactis, but the activities of different strains were very variable. In general, the glutathione reductase activities of L. lactis subsp. lactis are higher than those of L. lactis subsp. cremoris, and the activities were much higher when strains were grown aerobically. In addition, glutathione peroxidase is detectable in strain SK11, and the level was fivefold greater when the organism was grown aerobically than when the organism was grown anaerobically. Therefore, the presence of glutathione in L. lactis could result in greater stability under storage conditions and quicker growth upon inoculation, two important attributes of successful starter cultures.
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Pachapur, Vinayak Laxman, Prianka Kutty, Preetika Pachapur, Satinder Kaur Brar, Yann Le Bihan, Rosa Galvez-Cloutier, and Gerardo Buelna. "Seed Pretreatment for Increased Hydrogen Production Using Mixed-Culture Systems with Advantages over Pure-Culture Systems." Energies 12, no. 3 (February 7, 2019): 530. http://dx.doi.org/10.3390/en12030530.
Abstract:
Hydrogen is an important source of energy and is considered as the future energy carrier post-petroleum era. Nowadays hydrogen production through various methods is being explored and developed to minimize the production costs. Biological hydrogen production has remained an attractive option, highly economical despite low yields. The mixed-culture systems use undefined microbial consortia unlike pure-cultures that use defined microbial species for hydrogen production. This review summarizes mixed-culture system pretreatments such as heat, chemical (acid, alkali), microwave, ultrasound, aeration, and electric current, amongst others, and their combinations to improve the hydrogen yields. The literature representation of pretreatments in mixed-culture systems is as follows: 45–50% heat-treatment, 15–20% chemical, 5–10% microwave, 10–15% combined and 10–15% other treatment. In comparison to pure-culture mixed-culture offers several advantages, such as technical feasibility, minimum inoculum steps, minimum media supplements, ease of operation, and the fact it works on a wide spectrum of low-cost easily available organic wastes for valorization in hydrogen production. In comparison to pure-culture, mixed-culture can eliminate media sterilization (4 h), incubation step (18–36 h), media supplements cost ($4–6 for bioconversion of 1 kg crude glycerol (CG)) and around 10–15 Millijoule (MJ) of energy can be decreased for the single run.
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Stapleton, Raymond D., Dwayne C. Savage, Gary S. Sayler, and Gary Stacey. "Biodegradation of Aromatic Hydrocarbons in an Extremely Acidic Environment." Applied and Environmental Microbiology 64, no. 11 (November 1, 1998): 4180–84. http://dx.doi.org/10.1128/aem.64.11.4180-4184.1998.
Abstract:
ABSTRACT The potential for biodegradation of aromatic hydrocarbons was evaluated in soil samples recovered along gradients of both contaminant levels and pH values existing downstream of a long-term coal pile storage basin. pH values for areas greatly impacted by runoff from the storage basin were 2.0. Even at such a reduced pH, the indigenous microbial community was metabolically active, showing the ability to oxidize more than 40% of the parent hydrocarbons, naphthalene and toluene, to carbon dioxide and water. Treatment of the soil samples with cycloheximide inhibited mineralization of the aromatic substrates. DNA hybridization analysis indicated that whole-community nucleic acids recovered from these samples did not hybridize with genes, such asnahA, nahG, nahH,todC1C2, and tomA, that encode common enzymes from neutrophilic bacteria. Since these data suggested that the degradation of aromatic compounds may involve a microbial consortium instead of individual acidophilic bacteria, experiments using microorganisms isolated from these samples were initiated. While no defined mixed cultures were able to evolve14CO2 from labeled substrates in these mineralization experiments, an undefined mixed culture including a fungus, a yeast, and several bacteria successfully metabolized approximately 27% of supplied naphthalene after 1 week. This study shows that biodegradation of aromatic hydrocarbons can occur in environments with extremely low pH values.
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Gudipati, Smitha, Amit T. Vahia, Nicole Pahl, Indira Brar, Geehan Suleyman, Samia Arshad, Marcus Zervos, and George Alangaden. "407. Utilization of Blood Cultures, Risk factors and Outcomes of Bloodstream Infections in Patients Hospitalized with COVID-19." Open Forum Infectious Diseases 7, Supplement_1 (October 1, 2020): S271—S272. http://dx.doi.org/10.1093/ofid/ofaa439.602.
Abstract:
Abstract Background During the coronavirus disease 2019 (COVID-19) surge, there was a sharp increase of blood cultures (BC) performed at Henry Ford Health System (HFHS). However, the epidemiology and outcomes of bloodstream infections (BSI) in COVID-19 patients (pts) remains undefined. We report the utilization of blood cultures, risk factors and mortality associated with BSI in a large cohort of COVID-19 pts. Methods A retrospective analysis was performed of all COVID-19 pts that had BC performed during hospitalization at HFHS, a 5-hospital system in southeast Michigan. BSI was defined using NHSN criteria. Demographics, comorbidities, severity of illness, and outcome of pts with and without BSI were compared. Results From 3/10/2020 to 4/28/2020, 2541 pts were hospitalized with lab-confirmed COVID-19. 1393 (55%) of these pts had BC performed and 80 (5.74%) met criteria for BSI. Of the 84 pathogens identified, Staphylococcus aureus was most common (Figure 1). As compared to 1313 COVID-19 pts without BSI, those with BSI were older (70.1 vs 64.5 years, P = 0.0024). Other factors significantly associated with BSI included chronic kidney disease, higher mSOFA score, ICU stay and mechanical ventilation (all P < 0.0001) (Table 1). Multivariate analysis revealed age (OR, 1.07 CI [1.06–1.08]), ICU stay (OR, 7.91 [CI: 5.75–10.87]) and mSOFA score (OR, 1.29 [CI: 1.13–1.47]) were independent risk factors associated with mortality. BSI was not associated with increased mortality (Table 3). Conclusion Although more than half of hospitalized COVID-19 pts had BC done, the number of BSI were low suggesting overutilization of BC. BSI was associated with older age and disease severity. Mortality was not affected by BSI but was primarily driven by age and severity of illness. Disclosures Indira Brar, MD, Gilead (Speaker’s Bureau)janssen (Speaker’s Bureau)ViiV (Speaker’s Bureau) Marcus Zervos, MD, Melinta Therapeutics (Grant/Research Support)
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Schuster, Frederick L., and James J. Sullivan. "Cultivation of Clinically Significant Hemoflagellates." Clinical Microbiology Reviews 15, no. 3 (July 2002): 374–89. http://dx.doi.org/10.1128/cmr.15.3.374-389.2002.
Abstract:
SUMMARY The hemoflagellates, Trypanosoma spp. and Leishmania spp., are causal agents of a number of parasitic diseases having a major impact on humans and domestic animals over vast areas of the globe. Among the diseases are some of the most pernicious and deadly of human afflictions: African sleeping sickness, Chagas' disease, kala-azar, and Oriental sore. The organisms have complex, pleomorphic life cycles typically involving a vertebrate and an invertebrate host, the latter serving as a vector. In the vertebrate host, they are primarily blood and tissue parasites. In their transition from one host to another, the hemoflagellates undergo morphological, physiological, and biochemical changes that facilitate their growth and subsequent transmission. A major goal in the study of the hemoflagellates has been the cultivation in vitro of both vertebrate and invertebrate stages of the organisms. The first types of media used in their cultivation, and still useful for establishment of cultures, were undefined and contained a complex of ingredients. These gave way to semidefined formulations which included tissue culture media as a base and, as a next step, addition of tissue culture cells as a feeder layer to promote parasite growth. More recently developed media are completely defined, having replaced the feeder cells with various supplements. Serum, a sometimes-variable component of the media, can be replaced by various serum substitutes. This review focuses on the hemoflagellates that infect humans, describing stages in the development of media leading to the fully defined formulations that are now available for the cultivation of many of these organisms.
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Angelov, Angel I., Galya Petrova, Angel D. Angelov, Petya Stefanova, Innocent Y. Bokossa, Célestin K. C. Tchekessi, Maria L. Marco, and Velitchka Gotcheva. "Molecular Identification of Yeasts and Lactic Acid Bacteria Involved in the Production of Beninese Fermented Food Degue." Open Biotechnology Journal 11, no. 1 (September 21, 2017): 94–104. http://dx.doi.org/10.2174/1874070701711010094.
Abstract:
Background:Traditional Beninese fermented food Degue is widely consumed in Benin and other countries in West Africa. It was originally made from milk and millet flour, but currently other cereals are used as well. Nowadays, Degue production occurs by spontaneous fermentation in individual households and information about the microorganisms involved is currently limited.Objective:The microbiota of Degue from Benin has not been studied so far, but its growing production in the country sets a demand for revealing the biodiversity of the microbial population involved in the fermentation process in order to take future steps for development of industrial technology and offer products with improved quality and safety.Method:In the present study, yeast and lactic acid bacteria from raw materials for Degue production and from several Degue products were isolated and identified by molecular methods including RFLP and ITS1-5.8S-ITS2 rRNA gene sequence analysis in yeasts, and 16S rRNA gene sequence analysis in lactic acid bacteria.Results:Lactic acid bacteria isolates were assigned to eight species within the generaLactobacillus,Enterococcus,Pediococcus,StreptococcusandWeisella. Four species of yeasts were found in Degue:Cyberlyndnera fabianii,Candida glabrata,Kluyveromyces marxianus, andMeyerozyma caribbica.Conclusion:The microbial population revealed is unique to Beninese Degue and needs further characterization for development of defined starter cultures.
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Arioli, Stefania, Paola Roncada, Anna Maria Salzano, Francesca Deriu, Silvia Corona, Simone Guglielmetti, Luigi Bonizzi, Andrea Scaloni, and Diego Mora. "The relevance of carbon dioxide metabolism in Streptococcus thermophilus." Microbiology 155, no. 6 (June 1, 2009): 1953–65. http://dx.doi.org/10.1099/mic.0.024737-0.
Abstract:
Streptococcus thermophilus is a major component of dairy starter cultures used for the manufacture of yoghurt and cheese. In this study, the CO2 metabolism of S. thermophilus DSM 20617T, grown in either a N2 atmosphere or an enriched CO2 atmosphere, was analysed using both genetic and proteomic approaches. Growth experiments performed in a chemically defined medium revealed that CO2 depletion resulted in bacterial arginine, aspartate and uracil auxotrophy. Moreover, CO2 depletion governed a significant change in cell morphology, and a high reduction in biomass production. A comparative proteomic analysis revealed that cells of S. thermophilus showed a different degree of energy status depending on the CO2 availability. In agreement with proteomic data, cells grown under N2 showed a significantly higher milk acidification rate compared with those grown in an enriched CO2 atmosphere. Experiments carried out on S. thermophilus wild-type and its derivative mutant, which was inactivated in the phosphoenolpyruvate carboxylase and carbamoyl-phosphate synthase activities responsible for fixing CO2 to organic molecules, suggested that the anaplerotic reactions governed by these enzymes have a central role in bacterial metabolism. Our results reveal the capnophilic nature of this micro-organism, underlining the essential role of CO2 in S. thermophilus physiology, and suggesting potential applications in dairy fermentation processes.
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Filimon, Răzvan Vasile, Claudiu-Ioan Bunea, Ancuța Nechita, Florin Dumitru Bora, Simona Isabela Dunca, Andrei Mocan, and Roxana Mihaela Filimon. "New Malolactic Bacteria Strains Isolated from Wine Microbiota: Characterization and Technological Properties." Fermentation 8, no. 1 (January 13, 2022): 31. http://dx.doi.org/10.3390/fermentation8010031.
Abstract:
Malolactic fermentation (MLF) or biological decrease of wine acidity is defined as the enzymatic bioconversion of malic acid in lactic acid, a process performed by lactic acid bacteria (LAB). The procedures for the isolation of new indigenous LAB strains from the red wines produced in Copou Iasi wine center (NE of Romania) undergoing spontaneous malolactic fermentation, resulted in the obtaining of 67 catalase-negative and Gram-positive LAB strains. After testing in the malolactic fermentative process, application of specific screening procedures and identification (API 50 CH), two bacterial strains belonging to the species Oenococcus oeni (strain 13-7) and Lactobacillus plantarum (strain R1-1) with high yield of malolactic bioconversion, non-producing biogenic amines, and with active extracellular enzymes related to wine aroma, were retained and characterized. Tested in synthetic medium (MRS-TJ) for 10 days, the new isolated LAB strains metabolized over 98% of the malic acid at ethanol concentrations between 10 and 14 % (v/v), low pH (>3.0), total SO2 doses up to 70 mg/L and temperatures between 15 and 35 °C, showing high potential for future use in the winemaking process as bacterial starter cultures, in order to obtain high quality wines with increased typicity.
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Kitessa, Daniel A., Ketema Bacha, Yetenayet B. Tola, Mary Murimi, Soressa Gershe, and Meseret Guta. "Microbial Quality and Growth Dynamics in Shameta: A Traditional Ethiopian Cereal-Based Fermented Porridge." Fermentation 8, no. 3 (March 14, 2022): 124. http://dx.doi.org/10.3390/fermentation8030124.
Abstract:
Shameta is a traditional, Ethiopian, cereal-based fermented porridge exclusively prepared for lactating mothers. The aim of this study was to determine the microbial quality of Shameta samples collected from households of lactating mothers and to determine microbial dynamics and physicochemical changes during laboratory fermentation of Shameta. Isolation and characterization of the dominant microbes and analysis of the physicochemical properties of samples were done following standard microbiological methods and analytical techniques. Results of this study showed that the highest mean count of lactic acid bacteria (8.33 log cfu/g) was recorded in a sample from laboratory-fermented barley-based Shameta, and the lowest (5.88 log cfu/g) in Shameta made from a mixture of barley and maize (BMS). In both barley-based and maize-based laboratory-prepared Shameta, the microflora were dominated by LAB, followed by yeasts. The dominant LAB were the genus Lactobacillus (74.85%), followed by Enterococcus (15.79%). It could be concluded that Shameta collected from households of lactating mothers are fairly safe for consumption, as the stringent physicochemical conditions of the final product could inhibit the growth of pathogens. However, as Shameta is a traditional fermented porridge fed to lactating mothers, we call for a further improvement to the fermentation process by using defined starter cultures.
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Oláhné Horváth, Borbála, Diána Nyitrainé Sárdy, Nikolett Kellner, and Ildikó Magyar. "Effects of the high sugar content on the fermentation dynamics and some metabolites of wine-related yeast species Saccharomyces cerevisiae, S. uvarum and Starmerella bacillaris." Food Technology and Biotechnology 58, no. 1 (April 22, 2020): 76–83. http://dx.doi.org/10.17113/ftb.58.01.20.6461.
Abstract:
Starmerella bacillaris (synonym Candida zemplinina) is an important non-Saccharomyces yeast in winemaking with valuable oenological properties, accompanying Saccharomyces species in sweet wine fermentation, and has also been suggested for application as combined starter culture in dry or sweet wines. In this study, the major metabolites and nitrogen utilization of these yeasts are evaluated in the musts with high or extremely high sugar concentration. The change in the metabolic footprint of Saccharomyces cerevisiae, Saccharomyces uvarum and Starmerella bacillaris strains was compared when they were present as pure cultures in chemically defined grape juice medium with 220 and 320 g/L of sugar, to represent a fully matured and an overripe grape. Surprisingly, the extreme sugar concentration did not result in a considerable change in the rate of sugar consumption; only a shift of the sugar consumption curves could be noticed for all species, especially for Starmerella bacillaris. At the extreme sugar concentration, Starmerella bacillaris showed excellent glycerol production, moderate nitrogen demand together with a noticeable proline utilisation. The change in the overall metabolite pattern of Starmerella bacillaris allowed clear discrimination from the change of the Saccharomyces species. In this experiment, the adequacy of this non-Saccharomyces yeast for co-fermentation in juices with high sugar concentration is highlighted. Moreover, the results suggest that Starmerella bacillaris has a more active adaptation mechanism to extremely high sugar concentration.
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FEICHTINGER, MARLIES, SIGRID MAYRHOFER, WOLFGANG KNEIFEL, and KONRAD J. DOMIG. "Tetracycline Resistance Patterns of Lactobacillus buchneri Group Strains." Journal of Food Protection 79, no. 10 (October 1, 2016): 1741–47. http://dx.doi.org/10.4315/0362-028x.jfp-15-577.
Abstract:
ABSTRACT Lactobacilli are applied as starter cultures for controlled fermentation in the production of food and feed. Among other lactobacilli, members of the Lactobacillus buchneri group are used in fermented milk, wine, and silage. Most of the L. buchneri species used for the manufacturing of food or feed are already on the list for qualified presumption of safety status and are recommended as biological agents by the European Food Safety Authority. Consequently, new strains intended as food or feed additives do not require any additional safety check than confirming the absence of transferable antibiotic resistance determinants. Of these determinants, tetracycline resistance genes are especially predominant in lactobacilli. Within this study, a total of 128 strains belonging to the L. buchneri group (L. buchneri, L. diolivorans, L. farraginis, L. hilgardii, L. kefiri, L. kisonensis, L. otakiensis, L. parabuchneri, L. parafarraginis, L. parakefiri, L. rapi, L. senioris, and L. sunkii) were examined for their susceptibility to tetracycline. Tetracycline MICs were assessed by the broth microdilution method according to ISO 10932/IDF 223. Subsequently, the presence of tetracycline resistance genes was investigated by using PCR. In addition, selected strains were tested for a broader range of tetracycline resistance genes by using a microarray technique. Applying the tetracycline cutoff values defined by European Food Safety Authority for heterofermentative and obligately homofermentative lactobacilli, 96.9% of the strains would have been categorized as tetracycline resistant. However, none of the tested tetracycline resistance genes could be detected by PCR or microarray analysis. Furthermore, the MIC distribution of all strains was unimodal and at the high end of the tested tetracycline concentration range (4 to 256 μg/ml). Thus, these data suggest that tetracycline resistance in the L. buchneri group strains is intrinsic, which complies with the requirements defined in the qualified presumption of safety outline.
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Hanić, Azra, and Dragana Jevtić. "Human Resource Management Between Economy and Ethics – Research of Serbia and Bosnia and Hercegovina." Business Ethics and Leadership 4, no. 3 (2020): 127–36. http://dx.doi.org/10.21272/bel.4(3).127-136.2020.
Abstract:
This paper discusses economic and ethical issues that bring about certain limitations in human resource management as one of the basic organizational functions, through which the organization’s relationship with employees is expressed. The aim of this paper is to point out the ethical dimension of human resource management as a key organizational function, which has economic, but at the same time ethical responsibilities. In elaborating this problem, we started from the basic assumption that human resource management as an organizational function and theoretical concept should balance between economic and ethical requirements, which depends on the attitudes of managers as decision makers. In addition to the analysis of the existing literature in this field, an empirical research was conducted to verify the stated assumptions on the basis of a survey questionnaire, which explored the attitudes of managers. The results were processed by statistical methods in the SPSS program. The significance of this paper derives from the importance of employees for the organization and the sensitivity of the human dimension of the organization in relation to the economic one. Bad condition in human resources management in BiH and Serbia, as the countries on which our research is focused, with unfavorable situation on the labor market, low level of perception of needs by managers and knowledge (professionalism) required for experts in this field to achieve necessary influence and affirm an effective concept and practice, opens opportunities for unethical actions of organizations. Unethical practices can be generated by ignorance, employers ’greed for quick profits, and weak institutional influence. High distance of power is an unfavorable cultural factor that encourages the arbitrariness of individuals and prevents social control of the behavior of organizations. In these wanderings and undefined directions of institutional development, in these countries there is room for corruption, poor law enforcement (incomplete reform of the judicial system), insufficiently defined protection of private property, strong influence of political parties in all spheres of life, political and economic connection, significant share of state property, etc. On the ground of egalitarian culture, high social inequality and impoverishment of the majority of the population is created, which negatively affects education, health and distracts attention from the civic control of the government. Therefore, in the research we started from the assumption that the primary evaluation of the human and social function of business and employees as a purpose, not a means, positively affects the ethical practice of human resource management, which we tested over the average response of respondents employed in different positions in the organization. The results obtained are presented in the paper. Keywords: Business Ethics, Ethics, Employees, Economics, HRM, Organization.
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Ramsey, Alan H., Patrice Skonieczny, Diane T. Coolidge, Terry A. Kurzynski, Mary E. Proctor, and Jeffrey P. Davis. "Burkholderia cepaciaLower Respiratory Tract Infection Associated With Exposure to a Respiratory Therapist." Infection Control & Hospital Epidemiology 22, no. 7 (July 2001): 423–26. http://dx.doi.org/10.1086/501928.
Abstract:
AbstractObjective:To investigate and control a nosocomial outbreak ofBurkholderia cepacialower respiratory tract infection.Design:Outbreak investigation and case-control study.Setting:A 260-bed community hospital.Patients:Participants were mechanically ventilated intensive care patients without cystic fibrosis. A case was defined as a hospitalized patient with a sputum culture positive forB cepaciabetween January 1 and November 6, 1998.Methods:Respiratory therapy infection control policies and practices were reviewed; laboratory and environmental studies and a retrospective case-control study were conducted. Case-patients were matched with control-patients on age, gender, diagnosis, and type of intensive care unit.Results:Nine case-patients were identified;B cepacialikely caused pneumonia in seven and colonization in two. Two respiratory therapy practices probably contributed to the transmission ofB cepacia:multidose albuterol vials were used among several patients, and nebulizer assemblies often were not dried between uses.B cepaciawas grown from cultures of three previously opened multidose vials; pulsed-field gel electrophoresis patterns ofB cepaciafrom seven case-patients and two multidose vials were indistinguishable. Case-patients had longer durations of heated humidified mechanical ventilation (mean, 9.8 days vs 4.4 days;P=.03) and were more likely to have exposure to one particular respiratory therapist than controls (odds ratio, undefined; 95% confidence interval, 4.7-∞P=.001). The association with the respiratory therapist, a temporary employee, persisted after controlling for duration of heated humidified ventilation. No newB cepaciainfections were identified after control measures were implemented.Conclusions:B cepaciaprobably was transmitted among patients through use of extrinsically contaminated multidose albuterol vials. Respiratory therapy departments must pay close attention to infection control practices, particularly among new or temporary staff.
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Durban, E. M., P. D. Barreto, J. Hilgers, and A. Sonnenberg. "Cell phenotypes and differentiative transitions in mouse submandibular salivary gland defined with monoclonal antibodies to mammary epithelial cells." Journal of Histochemistry & Cytochemistry 42, no. 2 (February 1994): 185–96. http://dx.doi.org/10.1177/42.2.8288864.
Abstract:
Recognition of distinct cell phenotypes within a given organ is important in defining cell relationships during development and in analyzing the role of cell-cell and cell-matrix interactions in growth and differentiation. Phenotypic definition of dissociated heterogeneous cell populations is also essential for studies on mechanisms regulating expression of cell lineage-specific gene products. Mouse submandibular salivary gland (SSG) cell phenotypes in the course of differentiative transitions in vivo and after enzymatic dissociation in primary culture were defined with monoclonal antibodies (MAb) to mammary epithelial cells and polyclonal antibodies to functional cell products. Proacinar cells and differentiating and mature acinar cells were uniquely recognized by an MAb designated 50B8. Ductal cell components were uniquely recognized by an MAb designated JSE3. JSE3 immunoreactivity was particularly useful for detecting the emergence of two SSG duct cell phenotypes, striated ducts and the hormone-responsive granular convoluted tubules (GCTs). JSE3-positive striated duct-like cells were visualized as early as Day 2 after birth and emergence of GCT-like structures from striated ducts was apparent between Days 10 and 11. Differential reactivity of acinar and ductal cells in the developing SSG with either MAb 50B8 or JSE3 suggests the existence of intermediate progenitor cells restricted in their differentiation potential. An interesting pattern of immunoreactivity was observed with an MAb designated 33A10. During the first 2 weeks of SSG postnatal development, shared 33A10 immunoreactivity was observed among proacinar and differentiating acinar cells and all differentiating ductal segments. Coincident with a decrease in proliferative activity at about Day 18, 33A10 immunoreactivity became restricted to the GCT cell lineage before the appearance of GCT functional products, epidermal and nerve growth factors. Although the SSG antigen recognized by MAb 33A10 is presently undefined, its expression pattern suggest a molecule with a dual role in development and growth events and in hormone-dependent secretory function. Advantage was taken of the observed differential immunoreactivities to define the phenotypic identity of dissociated, mature SSG cells before and after culture. Dissociated SSG fractions enriched for either JSE3- or 50B8-positive cells could be maintained in short-term cultures without loss of expression of duct- or acinar cell-specific immunoreactivity. In addition to providing markers for defining dissociated SSG cells before and after culture, the described immunoreactivities may permit separation or enrichment of an early duct cell population before its commitment to a specific cell lineage. This approach may also provide the means to define regulatory signals involved in the differentiation of intermediate progenitor cells.
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Cashman, JD, AC Eaves, EW Raines, R. Ross, and CJ Eaves. "Mechanisms that regulate the cell cycle status of very primitive hematopoietic cells in long-term human marrow cultures. I. Stimulatory role of a variety of mesenchymal cell activators and inhibitory role of TGF-beta." Blood 75, no. 1 (January 1, 1990): 96–101. http://dx.doi.org/10.1182/blood.v75.1.96.96.
Abstract:
Abstract Long-term marrow cultures (LTMC) allow the proliferation and differentiation of primitive human hematopoietic progenitor cells to be maintained for many weeks in the absence of exogenously provided hematopoietic growth factors. Previous investigations focused on defining various types of cells that are present in this culture system and on measuring the cycling behavior of the different subpopulations of colony-forming cells maintained within it. These studies suggested that mesenchymal stromal elements derived from the input marrow play a key role in regulating the turnover of the most primitive, high- proliferative potential erythroid and granulopoietic colony-forming cells that are found almost exclusively in the adherent layer of LTMC. In this study we show that the re-entry into S-phase of these primitive hematopoietic progenitors that occurs after each weekly medium change is due to an as yet undefined constituent of horse serum, which is absent from fetal calf serum. However, this effect is not unique to the factor present in horse serum. It is also elicited by the addition to LTMC of several well-defined growth regulatory molecules, ie, platelet- derived growth factor (PDGF), interleukin-1 (IL-1), transforming growth factor alpha (TGF-alpha), and IL-2. None of these was able to stimulate hematopoietic colony-forming cells in methylcellulose assays, although all have known actions on mesenchymal cells including, in some cases, the ability to increase production of growth factors that can stimulate primitive high-proliferative potential hematopoietic progenitors in clonogenic assays. Interestingly, a stimulating effect was not obtained after addition of endotoxin to LTMC. TGF-beta, a direct-acting negative regulator that acts selectively on primitive hematopoietic progenitor cells if added to LTMC simultaneously with new medium or IL-1, blocked their stimulating activity. These results suggest a model in which indirect, local modulation of both positive and negative regulatory factors via effects on mesenchymal elements determines the rate of turnover of adjacent populations of very primitive hematopoietic cells that are normally maintained in a quiescent state in vivo.
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Cashman, JD, AC Eaves, EW Raines, R. Ross, and CJ Eaves. "Mechanisms that regulate the cell cycle status of very primitive hematopoietic cells in long-term human marrow cultures. I. Stimulatory role of a variety of mesenchymal cell activators and inhibitory role of TGF-beta." Blood 75, no. 1 (January 1, 1990): 96–101. http://dx.doi.org/10.1182/blood.v75.1.96.bloodjournal75196.
Abstract:
Long-term marrow cultures (LTMC) allow the proliferation and differentiation of primitive human hematopoietic progenitor cells to be maintained for many weeks in the absence of exogenously provided hematopoietic growth factors. Previous investigations focused on defining various types of cells that are present in this culture system and on measuring the cycling behavior of the different subpopulations of colony-forming cells maintained within it. These studies suggested that mesenchymal stromal elements derived from the input marrow play a key role in regulating the turnover of the most primitive, high- proliferative potential erythroid and granulopoietic colony-forming cells that are found almost exclusively in the adherent layer of LTMC. In this study we show that the re-entry into S-phase of these primitive hematopoietic progenitors that occurs after each weekly medium change is due to an as yet undefined constituent of horse serum, which is absent from fetal calf serum. However, this effect is not unique to the factor present in horse serum. It is also elicited by the addition to LTMC of several well-defined growth regulatory molecules, ie, platelet- derived growth factor (PDGF), interleukin-1 (IL-1), transforming growth factor alpha (TGF-alpha), and IL-2. None of these was able to stimulate hematopoietic colony-forming cells in methylcellulose assays, although all have known actions on mesenchymal cells including, in some cases, the ability to increase production of growth factors that can stimulate primitive high-proliferative potential hematopoietic progenitors in clonogenic assays. Interestingly, a stimulating effect was not obtained after addition of endotoxin to LTMC. TGF-beta, a direct-acting negative regulator that acts selectively on primitive hematopoietic progenitor cells if added to LTMC simultaneously with new medium or IL-1, blocked their stimulating activity. These results suggest a model in which indirect, local modulation of both positive and negative regulatory factors via effects on mesenchymal elements determines the rate of turnover of adjacent populations of very primitive hematopoietic cells that are normally maintained in a quiescent state in vivo.
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Knorr, David A., Zhenya Ni, Allison Bock, Vijay G. Ramakrishnan, Shaji Kumar, and Dan S. Kaufman. "Pluripotent Stem Cell-Derived Human Natural Killer Cells with Potent Anti-Multiple Myeloma Activity,." Blood 118, no. 21 (November 18, 2011): 4034. http://dx.doi.org/10.1182/blood.v118.21.4034.4034.
Abstract:
Abstract Abstract 4034 Natural Killer (NK) cells are lymphocytes of the innate immune system with anti-viral and anti-cancer activity. Over the past decade, they have gained interest as a promising cellular source for use in adoptive immunotherapy for the treatment of cancer. Most notably, NK cells play an important role in the graft-vs-tumor effect seen in allogeneic hematopoietic stem cell transplantation (allo-HSCT), and a better understanding of NK cell biology has translated into improved transplant outcomes in acute myelogenous leukemia (AML). Small studies have demonstrated a role for NK cell activity in multiple myeloma (MM) patients receiving allo-HSCT. Investigators have also utilized haplo-identical killer immunoglobulin-like receptor (KIR) mismatched NK cells for adoptive immunotherapy in patients with multiple myeloma (MM). Our group has focused on the development of NK cells from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) as a novel starting source of lymphocytes for immunotherapy. We have previously demonstrated potent anti-tumor activity of hESC-derived NK cells in vitro and in vivo against a variety of different targets. We have also shown that iPSC-derived NK cells from a variety of different somatic cell starting sources posses potent anti-tumor and anti-viral activity. Here, we demonstrate hESC- and iPSC-derived NK cell development in a completely defined, feeder-free system that is amenable to clinical scale-up. These cultures contain a pure population of mature NK cells devoid of any T or B cell contamination, which are common adverse bystanders of cellular products isolated and enriched from peripheral blood. Our cultures are homogenous for their expression of CD56 and express high levels of effector molecules known to be important in anti-MM activity, including KIR, CD16, NKG2D, NKp46, NKp44, FasL and TRAIL. We have now tested the activity of hESC- and iPSC-derived NK cells against MM tumor cells in order to provide a universal source of lymphocytes for adoptive immunotherapy in patients with treatment refractory disease. We find that similar to peripheral blood NK cells (PB-NK), hESC- and iPSC-derived NK cells are cytotoxic against 3 distinct MM cell lines in a standard chromium release cytotoxicity assay. Specifically, activated PB-NK cells killed 48.5% of targets at 10 to 1 effector to target ratios, whereas hESC (46.3%) and iPSC (42.4%) derived NK cells also demonstrated significant anti-MM activity. Also, hESC- and iPSC-derived NK cells secrete cytokines (IFNγ and TNFα) and degranulate as demonstrated by CD107a surface expression in response to MM target cell stimulation. When tested against freshly isolated samples from MM patients, hESC- and IPSC-derived NK cells respond at a similar level as activated PB-NK cells, the current source of NK cells used in adoptive immunotherapy trials. These MM targets (both cell lines and primary tumor cells) are known to express defined ligands (MICA/B, DR4/5, ULBP-1, BAT3) for receptors expressed on NK cells as well as a number of undefined ligands for natural cytotoxicity receptors (NCRs) and KIR. As these receptor-ligand interactions drive the anti-MM activity of NK cells, we are currently evaluating expression of each of these molecules on the surface of both the effector and target cell populations. Not only do hESC- and iPSC-derived NK cells provide a unique, homogenous cell population to study these interactions, they also provide a genetically tractable source of lymphocytes for improvement of the graft-vs-myeloma effect and could be tailored on a patient specific basis using banks of hESC-or iPSC-derived NK cells with defined KIR genotypes for use as allogeneic or autologous effector cells. Disclosures: No relevant conflicts of interest to declare.