Dissertations / Theses on the topic 'Antifungal lactic acid bacteria'

Thesis (MSc)--Stellenbosch University, 2003.
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ENGLISH ABSTRACT: Winemaking is an age-old tradition that dates back to as early as 6000 BC. In our modern era there are several insects and microorganisms that pose a threat to the grapevine, the environment and the final wine product. Farmers and winemakers are becoming aware of the threat and the fight against disease, spoilage and/or pathogenic microorganisms is on the rise. Currently, the natural environment is being altered through rural developments, pollution and disaster, which in turn is responsible for altering the natural micro flora. The result is a harsh battle between man and microorganism. The weapon used often against microorganisms is chemical preservatives, such as sulphur dioxide. These chemical preservatives change the nutritional value, quality and wholesomeness of the wine. Chemical preservatives suppress the quality of the wine with a reduction in wine consumption by the consumers. Until the 18th century, wine was regarded as a safe drink and prescribed by doctors. In the zo" century alcohol consumption became the focus point of some health campaigners. Medical science restored the good name of wine in the 1990s when it came to light that moderate red wine consumption may aid in preventing heart disease and assist in stress management. The only drawback that lowers consumption levels is the use of chemical preservatives. It is of utmost importance to place the focus on health issues and the development of natural preservation methods that are environmentally friendly and contributes to the overall wholesomeness of the wine. Due to these demands, the scientific community placed the focus of research projects on the development and enhancement of biopreservation methods, in order to minimise chemical preservation use. One of the most promising biocontrol agents is bacteriocins. These proteinaceous molecules produced by various lactic acid bacteria exert antimicrobial activity towards closely related organism. Research has shown that bacteriocins may aid in the prevention of wine-spoilage and enhance natural preservation techniques. Most of the research on biopreservation in food and beverages has been performed on the bacteriocins of LAB. No evidence could be found that indicated bacteriocin production by wine isolated LAB in South Africa. This study is therefore, of utmost importance and is considered to be novel pioneering work for the South African wine industry. The main objective of this study was to screen wine isolated LAB for the production of antimicrobial and/or antifungal compounds. This was followed by the isolation and characterisation of the produced bacteriocins. This study forms part of a greater project that focuses on wine preservation, under the auspices of the Institute for Wine Biotechnology.The research results in this study indicated the production of bacteriocins by wine isolated LAB of South African origin. It was found that numerous isolates exerted antimicrobial activity towards other wine associated LAB. The most predominant species that gave the highest activity was Lactobacillus brevis and Lactobacillus paracasei. Experimental results indicated that the bacteriocins produced by these two species were thermo-stable and active over a wide pH range, including the temperatures and pH values that reign in the South African wine environment. The antimicrobial activity was lost after treatment with proteolytic enzymes, such as proteinase K and lysozyme. The size, production and growth kinetic curves of the bacteriocins under investigation showed similar results that are comparable to other findings in the literature. Antifungal activity was detected against Botryfis cinerea that indicated limited inhibitory activity towards spore germination, but had no effect on hyphal growth. This study provides novel information regarding bacteriocin production by LAB isolated from the South African wine industry. The results indicate the suitability of these bacteriocins as possible biopreservatives in the wine environment. The proposed results obtained in this study will aid in the development of bacteriocinproducing, tailored made wine yeast or LAB that may in future, play vital roles in the winemaking process.
AFRIKAANSE OPSOMMING: Wynmaak is 'n eeu oue tradisie wat terugdateer tot so vroeg soos 6000 jaar v.C. In ons moderne eeu is daar verskeie insekte en mikro-organismes wat In bedreiging vir die wingerdstok, asook die omgewing en die finale wynproduk inhou. Boere en wynmakers word al hoe meer bewus van hierdie bedreiging, terwyl die stryd teen siektes, bederf en/of patogene mikro-organismes ook aan die toeneem is. Tans word die natuurlike omgewing deur landelike ontwikkeling, besoedeling en natuurlike rampe verander, wat op sy beurt weer verantwoordelik is vir die verandering van mikroflora. Die gevolg is 'n harde stryd tussen die mens en mikro-organismes. Die wapen wat gereeld ingespan word in die stryd teen mikro-organismes, is chemiese preserveermiddels, soos swaweidioksied. Hierdie chemiese preserveermiddels verander die voedingswaarde, kwaliteit en die voedsaamheid van die wyn. Dit onderdruk ook die gehalte van wyn, wat meebring dat minder wyn deur die verbruiker gedrink word. Tot en met die agtiende eeu is wyn deur dokters as 'n veilige drankie voorgeskryf. In die twintigste eeu het alkoholverbruik die fokuspunt van gesondheidskamvegters geword. In die 1990's het die mediese wetenskap wyn se goeie naam in ere herstel toe dit aan die lig gekom het dat In matige verbruik van rooiwyn moontlik hartsiektes kan voorkom en help om stres te beheer. Die enigste nadelige faktor wat verbruikersvlakke verlaag, is die gebruik van chemiese preserveermiddels. Dit is uiters noodsaaklik om die fokus op gesondheidskwessies te plaas en die ontwikkeling van natuurlike preserveermetodes wat omgewingsvriendelik is en tot die algehele voedsaamheid van wyn bydra. As gevolg van hierdie eise het wetenskaplikes die fokus geplaas op navorsingsprojekte vir die ontwikkeling en verbetering van biopreserveringsmetodes met die doelom die gebruik van chemiese preserveermiddels te verminder. Een van die belowendste biokontrolemiddels is bakteriosiene. Hierdie proteïenagtige molekule word deur verskeie melksuurbakterieë vervaardig en oefen anti-mikrobiese aktiwiteit teenoor nabyverwante organismes uit. Navorsing het getoon dat bakteriosiene moontlik kan help in die voorkoming van wynbederf en natuurlike preserveertegnieke kan verbeter. Die meeste van die navorsing op biopreservering in voedsel en drank is op die bakteriosiene van melksuurbakterieë uitgevoer. Geen bewys kon gevind word in Suid Afrika wat bakteriosienproduksie deur wyn-geïsoleerde melksuurbakterieë aangedui het nie. Hierdie studie is daarom baie belangrik en word as baanbreker werk vir die Suid Afrikaanse wynbedryf beskou. Die hoofdoel van hierdie studie was om wyn-geïsoleerde melksuurbakterieë vir die produksie van anti-mikrobiese en/of anti-fungiese substanse te toets. Dit is gevolg deur die isolasie en karakterisering van die geproduseerde bakteriosiene. Hierdie studie maak deel uit van 'n groter projek wat fokus op wynpreservering en wat onder leiding van die Instituut van Wynbiotegnologie uitgevoer word. Navorsingsresultate van hierdie studie dui op die produksie van bakteriosiene deur wyn-geïsoleerde melksuurbakterieë van Suid Afrikaanse oorsrong. Daar is gevind dat verskeie isolate anti-mikrobiese aktiwiteit teenoor ander wynverwante malksuurbakterieë uitgeoefen het. Die oorheersende spesie wat die hoogste aktiwiteit getoon het, was Lactobacillus brevis en Lactobacillus paracasei. Eksperimentele uitslae dui daarop dat die bakteriosiene wat deur hierdie twee spesies geproduseer word, termostabiel en aktief is oor 'n wye pH reeks, insluitende die temperature en pH-waardes wat in die Suid Afrikaanse wynomgewing voorkom. Die anti-mikrobiese aktiwiteit het verlore gegaan na behandeling met proteolitiese ensieme soos proteïnase K. Die groote, produksie en groeikinetika kurwes van die bakteriosiene wat ondersoek is, toon vergelykbare resultate met ander bevindings in die literatuur. Anti-fungiese aktiwiteit is opgemerk teen Botrytis cinerea, wat beperkte inhiberende aktiwiteit ten opsigte van spoorontkieming aangedui het, maar geen effek op hifegroei gehad nie. Hierdie studie verskaf nuwe inligting aangaande bakteriosienproduksie deur melksuurbakterieë wat van die Suid Afrikaanse wynomgewing geïsoleer is. Die resultate dui op die geskiktheid van hierdie bakteriosiene as moontlike biopreserveermiddels in die wynbedryf. Die voorgestelde resultate deur hierdie studie verkry sal help in die ontwikkeling van bakteriosien produserende, spesifiek vervaardigse wyngis of melksuurbakterieë, wat in die toekoms 'n baie belangrike rol in die wynmaakproses sal speel.

Fusarium head blight (FHB) is a widely occurring plant disease, which is caused by fungi in the genus Fusarium. FHB leads to mycotoxin accumulation on grain, which causes food safety risk and economic loss. In addition to chemical treatments, biological strategies, like application of lactic acid bacteria (LAB), could be useful in preventing and/or eradicating mycotoxigenic Fusarium growth and mycotoxin production.After comparision of the anti-Fusarium activities by a microdilution assay against Fusarium graminearum 08/RG/BF/51, Lactobacillus rhamnosus VT1 was found to have the highest anti-Fusarium activity. Response surface methodology (RSM) was employed to optimize the incubation conditions for the production of cell-free Lactobacillus culture supernatant (CFLCS) from the strain. The best combination included 34??C, 55 hours, and shaking at 170 rpm for production of CFLCS from L. rhamnosus VT1. Under these incubation conditions, a 10% cell-free culture of Lactobacillus rhamnosus VT1 inhibited 83.7% of the Fusarium growth on microplate. MIC value of the CFLCS with a 104 conidia /well inoculum concentration is 18%.To identify the mechanisms of anti-Fusarium activity, a stepwise regression, with ?? to enter = 0.15 and ?? to remove = 0.15, was performed to analyze the data of the RSM design. It was indicated that pH, total acidity, and 3-phenyllactic acid were the most important factors and could be used to explain 39.2% variation of the anti-Fusarium activity. In addition, proteinaceous compounds might be important due to the possible synergistic effect in the CFLCS. CFLCS applied directly to grain not only prevented Fusarium growth, but also changed mycotoxin accumulation. Fusarium growth was inhibited completely by a 50% concentration (V/V) of the CFLCS applied on rice media after 14 days incubation, and almost no mycotoxins were detected. Concentrations of 15%, 30% and 50% of CFLCS as steeping water inhibited Fusarium growth and mycotoxin accumulation on barley in the malting process. Almost no mycotoxins were detected in the samples treated by 50% CFLCS. However, the germination ability of the barley samples was inhibited. In general, the CFLCS showed potential effective anti-Fusarium activity. However, the strategies of application of the CFLCS on grain should be further investigated.

A large amount of cheese is lost every year due to mold contamination. Biopreservation, which is the use of biological entities (microbes) and their metabolites to suppress microbial spoilage instead of chemical preservatives has lately gained increasing interest. Lactic acid bacteria (LAB) have the potential for use in biopreservation, because they are safe to consume and naturally exist in many foods. In this study, fifteen strains of lactobacilli isolated from dairy products, vegetables, and fermented pickles were tested by agar overlay assay for their anti-mold activity. Six strains grown on MRS agar showed strong inhibitory activity against a target mold (Penicillium sp. at 105 spores/ml) isolated from the surface of Cheddar cheese. The isolates were identified by biochemical tests using API CHL50 strips. Five strains were identified as Lactobacillus plantarum, and one strain as Pediococcus pentasaceus. Well-diffusion method was used to demonstrate anti-mold activity in concentrated cell-free supernatants. Supernatants from all strains showed inhibition of the target mold (indicator). The anti-mold compound(s) produced by all the strains was heat-resistant (100o C for 15 min). Supernatants from 5 strains retained the anti-mold activity when the pH was adjusted to 6.8 ± 0.2, while one strain DC2 isolated from cheese lost its anti-mold activity at that pH. Temperature of incubation of cultures affected anti-mold activity. The optimum was 37o C. Very little or no inhibition was noted when cultures were incubated at either 10 or 55 °C. A preliminary study of applying anti-mold lactobacilli in Cheddar cheese was completed. Anti-mold LAB was added to the cheese milk as an adjunct to give 105 cfu/ml. After 1-week and 1-month ripening, mold (10~20spores) was added on to the surface, and the cheese was wrapped loosely. The appearance of the mold on cheese surface was monitored. Mold was not present on the 1-week old cheese “NB in milk” until the 6th day after the control cheese (made without strain NB) showed signs of mold. The 1-month old cheese “NB in milk ” extended the shelf life 17 days longer than the control cheese.

La sicurezza e la qualità degli alimenti sono tutt’ora un problema critico per i paesi in via di sviluppo. Le diete a basso contenuto di acido folico, per esempio, possono causare gravi problemi di salute, soprattutto nei bambini. Gravi disturbi legati al tubo neurale (DTN) nei neonati possono derivare infatti da madri che hanno insufficiente apporto di acido folico (400-600 g / giorno) durante il periodo di gravidanza. Inoltre, se non adeguatamente protetti o trattati, I prodotti alimentari possono essere vettori di funghi e batteri patogeni rappresentando una fonte potenziale di malattie per l’uomo e una perdita economica per le industrie agro-alimentari. Nella seguente tesi si è quindi quindi studiato il ruolo di batteri lattici selezionati (LAB) in grado di aumentare il valore nutrizionale del latte attraverso la produzione di acido folico durante il processo di fermentazione. Inoltre, ci si è concentrati sul loro uso come "bio-conservanti" contro funghi e batteri, attraverso la sintesi di composti antimicrobici (batteriocine) in grado di inibire la crescita di funghi filamentosi e/o batteri patogeni.
The safety and quality of food are still a critical issue in developing countries. Diets with a low content of folic acid, for example, may cause serious health problems, especially in children. Severe disorders related to neural tube (NTD) in infants may arise from mothers having inadequate intakes of folic acid (400-600 g/dia) during the mother pregnancy period. Moreover foods, when not properly protected or treated, can be vectors of pathogenic fungi and bacteria thereby representing a potential source of human diseases and an economical loss for the food industry. In the following thesis we have therefore investigated the role of selected lactic acid bacteria (LAB) in increasing the nutritional value of milk through the production of folic acid during the fermentation process. In addition, we focused on their use as “bio-preservatives” against fungal and bacterial spoilage, through the synthesis of antimicrobial compounds (bacteriocins) able to inhibit the growth of filamentous fungi and /or pathogenic bacteria.

Les produits laitiers fermentés tels que les yaourts, les laits fermentés et les fromages frais, occupent une place importante dans l’économie française. La stabilité de ces produits et leurs chances d’exportation sont cependant limitées par de fréquentes altérations fongiques. De plus, l’augmentation des résistances de certains champignons aux conservateurs chimiques ainsi que la forte demande des consommateurs pour des produits dépourvus d’additifs poussent les industriels à en réduire l’ajout. Dans ce contexte, il est nécessaire de développer des alternatives innovantes, telle que la bio-conservation. Les bactéries lactiques, utilisées depuis des millénaires dans la fermentation de nombreux aliments, et généralement reconnues comme inoffensives pour la santé, sont potentiellement de bonnes candidates pour la bio-conservation. Dans le but d’obtenir une ou deux souches de bactéries lactiques antifongiques, capables d’être compétitives au sein de produits laitiers fermentés tels que le yaourt, une collection de bactéries lactiques antifongiques a d’abord été constituée. Pour cela, un criblage de colonies isolées de laits crus de vache, de chèvre et de brebis a été effectué sur une période d’une année. Ce criblage, ciblé contre 4 champignons communément retrouvés dans les produits laitiers contaminés, a abouti à l’isolement de 1235 colonies de bactéries lactiques antifongiques. Ceci a permis d’évaluer la biodiversité des bactéries lactiques antifongiques d’une part, et celle des champignons, d’autre part, dans ces échantillons de lait, afin d’observer une éventuelle corrélation entre la présence de champignons et l’expression des activités antifongiques. L’influence de l’origine du lait, de la période d’échantillonnage, du milieu d’isolement et du champignon ciblé, sur le pourcentage de colonies actives isolées a été mise en évidence. Parmi les champignons ciblés, Pénicillium expansum était le plus facilement inhibé, et la majorité des colonies ont été isolées durant la troisième période d’échantillonnage, majoritairement sur les milieux à base de MRS. Les laits de vache et de chèvre se sont révélés être des réservoirs de bactéries lactiques antifongiques, contrairement aux laits de brebis. La majorité des bactéries lactiques antifongiques isolées et identifiées appartenait au genre Lactobacillus, majoritairement du groupe Lb. casei. Onze isolats, dont 10 appartenant au groupe Lb. casei, ont été sélectionnés selon l’intensité de leur activité antifongique et leur spectre d’action sur milieu MRS. Certaines de leurs propriétés technologiques ont été caractérisées, en vue de leur utilisation comme cultures protectrices dans des produits laitiers fermentés. Leur activité antifongique a également été testée dans le lait et dans le yaourt, contre 6 contaminants fongiques communément responsables d’altérations dans les yaourts. Une souche, Lb. harbinensis K.V9.3.1Np, a révélé de fortes activités antifongiques dans le yaourt contre 6 cibles fongiques. Les études complémentaires effectuées ont permis de montrer que la variation de certains paramètres technologiques (présence ou absence de saccharose, temps de fermentation) n’avait pas d’influence sur l’activité antifongique de cette souche. La découverte du potentiel antifongique de Lb. harbinensis K.V9.3.1Np est innovante. Cette espèce, isolée pour la première fois en 2005 d’un produit fermenté végétal, n’avait encore jamais été décrite comme présentant des activités antimicrobiennes. Sa forte activité antifongique dans le yaourt fait de Lb. harbinensis K.V9.3.1Np un bon candidat pour la bioconservation de produit(s) laitier(s) fermenté(s)
Fermented dairy products such as yogurt, fermented milks and fresh cheeses are of great importance in the French economy. The stability of these products and export opportunities are however limited by frequent fungal spoilages. In addition, the increase of fungal resistances to Chemical preservatives and the strong consumer demand for products deprived of Chemical additives are pushing manufacturers to reduce the quantities of added Chemical preservatives in these products. In this context, it is necessary to develop alternatives to classical food preservation methods, such as biopreservation. Lactic acid bacteria (LAB), used for millennia for diverse food fermentations, and generally recognized as safe for human health, can potentially be used for biopreservation. In order to select 1 or 2 LAB strains with antifungal activity capable to compete in fermented dairy products such as yogurt, a collection of antifungal LAB was first created. This was done by screening colonies isolated from cow, goat and ewe raw milk samples over a one-year period. This screening step, targeted against 4 fungi found in contaminated dairy products, resulted in the isolation of 1235 antifungal colonies. The biodiversity of the isolated antifungal LAB was then determined along with that of the fungi found in the different raw milks, in order to observe a possible correlation between the presence of fungi and the expression of antifungal activities. The influence of milk origin, sampling period, isolation medium and targeted fungus on the percentage of isolated active colonies was highlighted and clearly showed that both cow and goat milks were reservoirs of antifungal LAB. Among the targeted fungi, P. expansum was more easily inhibited, and the majority of colonies were isolated during the third sampling period, mainly on MRS-based media. The majority of identified antifungal LAB belonged to the genus Lactobacillus, mainly to the Lb. casei group. Eleven isolates, including 10 belonging to the Lb. casei group, were selected from these lactobacilli, according to their activity level and action spectrum in MRS medium. Some of their technological properties were characterized for their potential use as protective cultures in fermented dairy products and their antifungal activity was tested in milk and yogurt. To do this, 6 fungal contaminants commonly encountered in yogurt spoilage were used. A particular strain, Lb. harbinensis K.V9.3.1Np, showed a strong antifungal activity in yogurt. Additional experiments showed that the variation of technological parameters (presence or absence of sugar, fermentation time) had no influence on the antifungal activity of this strain. This is the first time that an antifungal potential has been observed for Lb. harbinensis, a species isolated for the first time in 2005 from a fermented vegetable product. Because of its effectiveness in yogurt, Lb. harbinensis K.V9.3.1Np is a promising strain for biopreservation of fermented dairy product(s)

La contamination fongique des produits laitiers est à l’origine de pertes économiques conséquentes et de gaspillage alimentaire. Dans un contexte de demande pour plus de « naturalité », les cultures de bioprotection et leurs métabolites représentent une alternative d’intérêt aux conservateurs chimiques pour lutter contre ces contaminants.Les objectifs de cette thèse étaient i) de sélectionner des micro-organismes présentant une activité antifongique, pour élaborer des cultures de bioprotection applicables dans des produits laitiers, et ii) d’étudier les composés potentiellement supports de l’activité antifongique observée. Dans un premier temps, l’activité antifongique de 32 souches de bactéries lactiques et propioniques a été étudiée en modèles « fromage » et « yaourt ». L’étude de combinaisons de souches et de leur innocuité a conduit à sélectionner 2 combinaisons binaires de lactobacilles (A1 et A3). Leur efficacité et applicabilité a été évaluée à l’échelle pilote en fabrication de crème fraîche et de fromage.Les challenges tests et tests d’usages ont montré que selon le produit laitier, A1 et A3 ont une activité antifongique similaire ou supérieure que les cultures bioprotectrices commerciales. Selon l’inoculum ajouté, ces cultures n’impactent pas les caractéristiques technologiques et organoleptiques des produits laitiers. Des méthodes chromatographiques des composés antifongiques suivies d’analyses statistiques ont permis de mettre en évidence des « cocktails » de 2 à 17 composés, selon la matrice et la culture considérée, qui sont probablement supports de l’activité antifongique.Ces travaux contribuent à une meilleure compréhension des mécanismes d’action de l’activité antifongique et devraient conduire au développement de cultures antifongique pour remplacer les conservateurs dans les produits laitiers
Fungal contamination of dairy products is responsible for economic losses and food waste. In a context of “preservative-free” product demand, bioprotective cultures and their metabolites represe,t an alternative of interest of chemical preservatives to control these spoilers.The objective of this study was i) to select microorganisms exhibiting an antifungal activity, in order to elaborate bioprotectivecultures applicable in dairy products, and ii) to study the compounds potentially supporting the observed activity. Firstly, the antifungal activity of 32 strains of lactic acid and propionic bacteria screened in cheese model and yogurt. Strain combinaison study and safety assessment led to the selection of 2 binary lactobacilli combinations (A1 and A3). Their efficiency and applicability were then evaluated in pilot-scale productions of sour cream and cheese.Challenge and shelf life tests showed that depending on the dairy product, A1 and A3 have a similar or higher antifungal activity than the commercial bioprotective cultures. In addition, depending of inoculum, A1 and A3 did not impact the technological and organoleptic characteristics. Chromatographic methods and statistical analyses allowed identifying cocktails of 2 to 17 compounds, according to the considered dairy product and culture that probably support the antifungal activity.The obtained results contribute to a better understanding of the antifungal activity action mechanisms and should lead to the development of antifungal cultures to replace preservatives in dairy products

The glycopeptide antibiotics vancomycin and teicoplanin are used to treat infections caused by Gram positive bacteria. The formation of nascent peptidoglycan chains and cross linking of the cell wall is inhibited because the drugs bind specifically to the D-alanyl-D-alanine portion of the pentapeptide chain in peptidoglycan precursors. Plasmid-mediated, high-level resistance to both antibiotics in Enterococcus sp. is associated with production of a novel D-alanine:D-alanine (D-Ala:D-Ala) ligase of altered substrate specificity. This enzyme, VanA, synthesises the depsipeptide D-alanyl-D-lactate (D-Ala-D-Lac), which is incorporated into cell wall precursors, instead of D-Ala-D-Ala. Vancomycin has a 1000 fold lower affinity for cell wall precursors terminating in the hydroxyacid. VanA and other plasmid-borne van genes essential for high-level glycopeptide resistance in enterococci lie within the inverted repeats of a transposon; Tn1546, which has a distinctly different G+C ratio to enterococcal DNA, suggesting an exogenous origin. Lactic acid bacteria such as Lactobacillus sp. and Leuconostoc sp. are intrinsically resistant to glycopeptide antibiotics. Analysis of their cell wall precursors reveals that they terminate in D-Lac, suggesting a similar mechanism of resistance to that of the enterococci. The mechanism of cell wall synthesis in vancomycin-sensitive and resistant lactic acid bacteria and VanA-type enterococci was investigated. The D-Ala:D-Ala ligase from the glycopeptide-sensitive lactic acid bacterium, Lactobacillus delbrueckii, was purified directly from cell extracts and characterised. No D-Ala:D-hydroxyacid ligase activity was detected in extracts from the glycopeptide-resistant Lactobacillus brevis. Subsequently, the ligase of Leuconostoc mesenteroides (Lmddl), which had already been sequenced, was cloned and overexpressed, to allow purification and characterisation of the enzyme.

Lactic acid bacteria were isolated from 10 samples of the traditionally fermented foods (5 samples of Vietnamese fermented pork roll and 5 samples of the salted field cabbage) and 5 samples of fresh cow milks collected from households in Vietnam. 22 strains of lactic acid bacteria were isolated for inhibition to Lactobacillus plantarum JCM 1149. Of these, only 2 strains including DC1.8 and NC1.2 have rod shape, the others have coccus shape. 7 strains showing higher antibacterial activity were selected for checking spectrum of antibacteria with indicator bacteria consistting of Bacillus subtilis ATCC 6633, Enterococcus faecium JCM 5804 and Staphylococcus aureus TLU. By which, 3 strains including NC3.5 (from Vietnamese fermented pork roll), DC1.8 (from salted field cabbage) and MC3.19 (from fresh cow milk) were selected because of their higher antibacterial ability. However, the antibacterial activity of the lactic acid bacteria can be based on their disposable compounds and some other antibacterial compounds produced during their growth (such as lactic acid, H2O2, bacteriocins, etc.). For seeking lactic acid bacteria with capability of producing bacteriocins, antibacterial compounds with protein nature, 3 above strains were checked sensitiveness to proteases (including protease K, papain, α – chymotrypsin and trypsin). Because bacteriocins are proteinaceous antibacterial compounds, so their antibacterial activity will be reduced if proteases are added. The result showed DC1.8 and MC3.19 were capable of producing bacteriocin during culture process. They were identified as Lactobacillus acidophilus and Lactococcus lactis and classified, respectively, based on analysis chemical characterisitcs by standard API 50 CHL kit and phylogeny relationship by 16s rRNA sequences.
Các chủng vi khuẩn lactic được phân lập từ 10 mẫu thực phẩm lên men truyền thống (5 mẫu nem chua, 5 mẫu dưa cải bẹ muối) và 5 mẫu sữa bò tươi được thu thập từ các hộ gia đình ở Việt Nam. 22 chủng vi khuẩn lactic đã được phân lập với tiêu chí có khả năng kháng lại vi khuẩn kiểm định Lactobacillus plantarum JCM 1149. Trong số đó, 2 chủng DC1.8 và NC1.2 có tế bào hình que, các chủng còn lại có tế bào hình cầu. 7 chủng thể hiện hoạt tính kháng khuẩn cao được lựa chọn để xác định phổ kháng khuẩn rộng hơn với ba loài vi khuẩn kiểm định Bacillus subtilis ATCC 6633, Enterococcus faecium JCM 5804 và Staphylococcus aureus TLU. Từ đó lựa chọn được 3 chủng có hoạt tính kháng khuẩn cao hơn hẳn. Các chủng này gồm NC3.5 phân lập từ nem chua, DC1.8 phân lập từ dưa cải bẹ muối và MC3.19 phân lập từ sữa bò tươi. Tuy nhiên, hoạt tính kháng khuẩn của vi khuẩn lactic bao gồm những hợp chất nội tại có trong nó và cả những hợp chất được sinh ra trong quá trình phát triển của nó (như axit lactic, H2O2, bacteriocin, …). Với định hướng tìm chủng vi khuẩn lactic có khả năng sinh bacteriocin, chất kháng khuẩn có bản chất protein, 3 chủng trên được kiểm tra độ nhạy cảm với các protease (gồm protease K, papain, α – chymotrypsin và trypsin). Do bacteriocin là chất kháng khuẩn có bản chất protein nên hoạt tính kháng khuẩn của chúng sẽ bị giảm nếu protease được bổ xung vào. Kết quả lựa chọn được chủng DC1.8 và MC3.19 có khả năng sinh bacteriocin. Hai chủng này được phân loại đến loài nhờ vào phân tích đặc điểm sinh hóa bằng kit API 50 CHL và mối quan hệ di truyền thông qua trình tự gen 16s rRNA. Kết quả phân loại đã xác định chủng DC1.8 thuộc loài Lactobacillus acidophilus và chủng MC3.19 thuộc loài Lactococcus lactis.

This thesis is an investigation into the production of exopolysaccharides (EPS) produced by strains of Lactobacillus delbrueckii ssp. bulgaricus and Lactococcus lactis ssp. cremoris. These are used in the dairy industry for the production of yoghurt and fermented drinks products. For many years EPS producing lactic acid bacteria have been used by the dairy industry as a thickening agent in the production of yoghurt. However, this EPS producing trait is unstable and is readily lost which can cause an alteration in the texture of the final product. It was found that all the strains of Lb. delbrueclcii ssp. bulgaricus and Le. /aetis ssp. eremoris produced quantities of EPS that could be used for further analysis. They were found to be in the molecular weight range of 6.6 x 1 06g /mol to 1.26 x 1011 glmol and were composed of different quantities of glucose, galactose and rhamnose. Temperature, carbon source and shaking all affected the quantities of EPS produced by all strains of Le. laetis ssp. eremoris. The firmness and viscosity of fermented milks produced by strains of Lb. delbrueckii ssp. bulgaricus were higher than those produced by strains of Le. laetis ssp. cremoris indicating that firmness and viscosity are not solely related to the levels of EPS production. A 40kb plasmid was found in all strains of Le. /aetis ssp. cremoris that could potentially contain the genes for EPS production. The plasmid could not be removed using elevated temperature or with the addition of acriflavin. Fourier transform infrared spectroscopy (FTIR) showed that it was possible to differentiate different strains based on their spectra and that differences were found in the protein and EPS regions of the spectra. It was also established that the age of culture, whether the growth medium was liquid or solid and the carbon source of the growth media had an effect on the FTIR spectra produced and the ability to differentiate between strains. There is further potential to develop this technique to provide a quick and easy method of identifying strains of lactic acid bacteria and monitor their EPS producing ability.

Ce travail de thèse a permis de décrire la contamination importante des grains du café de (Coffea canephora variété robusta) par des moisissures au cours des traitements post récolte des cerises de café par la voie sèche, dans une zone tropicale humide. La stratégie d’échantillonnage mise en place à consister à faire des prélèvements durant deux années successives (2008 et 2009) sur des sites localisés dans les principales zones de production du café en Côte d’Ivoire. A partir de 31 échantillons de cerises, grains et coques de café, 218 souches sauvages de moisissures ont été isolées sur milieu Potato Dextrose Agar (PDA) et identifiées. Ces champignons filamenteux sont répartis comme suit : Aspergillus section Nigri (52%) ; Aspergillus verts (13%), Penicillium (10%), Mucor (16%), Fusarium (4%), autre (5%). Les Aspergillus section Nigri qui comptent le complexe Aspergillus niger agreggate et Aspergillus carbonarius représentent un peu plus de la moitié de la population fongique soit 52%, soit 30% en 2008 et 70% en 2009, de la flore fongique totale. Ce groupe a fait l’objet d’une caractérisation morphologique. L’étude du potentiel mycotoxinogène des Aspergillus section Nigri isolées du café robusta a démontré qu’en plus de l’OTA, certaines souches d’Aspergillus Nigri produiraient de l’aflatoxine. Cependant l’espèce Aspergillus carbonarius reste la plus ochratoxinogène (0,6 µg et 15µg d’OTA/g de milieu gélosé). En plus des moisissures 44 souches de bactéries lactiques (LAB) ont été isolées à partir de la pulpe fraîche de café. Les caractères morphologiques, biochimiques et culturaux ont été étudiés. L’identification moléculaire des bactéries a permis de les classer dans le groupe de Lactobacillus plantarum sp. Après un criblage orienté, deux souches de LAB avec un effet important d’inhibition de croissance des moisissures mycotoxinogènes ont été sélectionnées. Les deux souches de Lactobacillus plantarum ont démontré une activité antifongique contre les souches d’Aspergillus carbonarius hautement ochratoxinogènes. Par conséquent la prévention de la mycotoxinogenèse sur café robusta, pourrait passer par l’inhibition de la croissance de certaines moisissures ochratoxinogènes. Les résultats acquis au cours de ce travail de thèse serviront de base afin de poursuivre cette étude d’une part avec des essais in situ pour tester l’efficacité des LAB sélectionnées et d’autre part, rechercher les biomolécules actives contre la germination des spores contaminants naturels post récolte en particulier des cerises de café en Côte d’Ivoire et des fruits et légumes en général
One of the objectives of this thesis was to describe the significant contamination of robusta coffee beans (Coffea canephora) by moulds during the post-harvest processing of coffee cherries in the dry process. The sampling strategy was to take samples for two consecutive years (2008 and 2009) from different areas of coffee production in Ivory Coast and on the other hand, from the same area but from coffee producers using different methods of drying of coffee beans. From 31 samples, 218 wild strains of fungi were isolated on Potato Dextrose Agar (PDA) media and identified. These filamentous fungi were as follows: black Aspergilli (52%); green Aspergilli (13%), Penicillium (10%), Mucor (16%), Fusarium (4%) and others (5%). The black Aspergilli were found to include Aspergillus niger and Aspergillus carbonarius representing 52% of the fungal population, with a proportion of 30% in 2008 and 70% in 2009 of the total fungal flora. This group was selected to study more about their mycotoxin production. Most strains grown on media and at specific incubation conditions, were capable of producing one or more kinds of mycotoxins. Analysis of mycotoxins from fungi isolated from less than a hundred robusta coffee showed that ochratoxin A (OTA) was not the only mycotoxin that may contaminate the robusta coffee in Ivory Coast. Indeed, several strains belonging to the species Aspergillus Nigri group had shown their ability to produce not only ochratoxin A but also aflatoxin. However, the species A. carbonarius remains as the most ochratoxigenic strain but it does not produce aflatoxin.In parallel to the isolation of fungi, 44 strains of lactic acid bacteria (LAB) were also isolated from fresh coffee cherries, harvested in Ivory Coast in 2009. The morphological, biochemical and growth characteristics were studied. Molecular identification of strains ranked them to be in the group of Lactobacillus plantarum sp. After a screening experiment, it was possible to select two strains of LAB with a significant effect of inhibiting fungal growth by producing mycotoxins. The two strains of Lactobacillus plantarum showed antifungal activity against strains of Aspergillus carbonarius which is highly ochratoxigenic. Therefore the prevention of mycotoxigenicity of robusta coffee, could be rised by inhibiting the growth of certain ochratoxigenic fungi. The results achieved in this thesis serve as a basis to continue the study on one hand with field trials to test the effectiveness of selected LAB on the other hand, look for active biomolecules against spore germination of contaminants especially the natural post-harvest coffee beans in Ivory Coast and fruits and vegetables in general

Thesis (MSc)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: The presence and growth of lactic acid bacteria (LAB) in wine and their influence on wine quality has received much attention in recent years. Lactic acid bacteria are responsible for conducting malolactic fermentation (MLF) in wine. The benefits associated with malolactic fermentation in terms of deacidification of wine and the contribution to wine flavour and complexity have also recently been the topic of research. It is impossible to describe malolactic fermentation as distinctly desirable or undesirable in terms of its influence on the final quality of wine. The benefits and disadvantages are dependent upon viticultural region, grape variety, wine composition, winemaking techniques and the style and objectives of the winemaker. Brandy production is a multi-stage process in which base wine production, distillation technique and wood maturation all have a large influence on the final chemical profile and organoleptic quality of the brandy. The volatile composition of the base wine, which basically undergoes a concentration process during the subsequent double distillation phase, is critical in determining the aroma and flavour quality of the final brandy product. Thus, the brandy is only as good as the base wine it is distilled from. The aims of this study were to determine the effect of lactic acid bacteria and spontaneous malolactic fermentation on the quality of brandy base wine and the resulting distillate, and to determine which LAB species had been responsible for the occurrence of spontaneous MLF. This study showed that LAB are present at high numbers and are able to conduct spontaneous MLF of brandy base wines. It was shown that the incidence of spontaneous MLF varied from year to year. In 1998, 50% of the commercially produced base wines had undergone partial MLF prior to distillation. In 1999 and 2000 respectively, 34% and 45% of the commercial base wines had undergone partial MLF prior to distillation. The occurrence of spontaneous MLF had an influence on the chemical composition and the sensory quality of the base wine and distillate. There was an increase in the concentrations of ethyl lactate, acetic acid and diethyl succinate in samples that had undergone MLF. There was also a decrease in the concentrations of esters, such as iso-amyl acetate, ethyl acetate, ethyl caproate, hexyl acetate and 2-phenethyl acetate in these same samples. Sensory evaluation of the base wines and distillates demonstrated that samples that had undergone MLF differed significantly from samples that had not undergone MLF. It was also shown that distillates that had not undergone MLF had a slightly better aroma profile than those that had. Sweet aromas, like chocolate and caramel, as well as negative aromas, like chemical or solvent, were more prominent in brandy distillates that had undergone MLF. Herbaceous and fruity aromas were more intense in distillates not having undergone MLF. Fifty-four strains, all Gram-positive and catalase negative, were isolated at different stages of brandy production. Seven strains were isolated from the grape juice, 15 strains were isolated from the base wine, 20 strains were isolated during MLF and 12 strains were isolated from the base wine after MLF had been completed. Based on C02 production from glucose and gluconate, 17 strains were classified as facultatively heterofermentative and 37 strains as obligately heterofermentative. Fifteen of the 37 obligately heterofermentative strains were rod-shaped and were regarded as lactobacilli. The remaining 22 strains were oval or cocci-bacilli shaped. The isolates were identified to species level by using numerical analysis of the total soluble cell protein patterns, 16S rRNAsequencing and polymerase chain reaction (PCR) with species-specific primers. The facultative heterofermentative lactobacilli were identified as Lactobacillus paracasei and Lactobacillus p/antarum. The fifteen obligately heterofermentative lactobacilli were identified as members of the species Lactobacillus brevis, Lactobacillus verrniforme, Lactobacillus buchneri and Lactobacillus hi/gardii. The 22 obligate heterofermentative isolates, with a coccoid morphology, could be grouped into two clusters and were identified as Oenococcus oeni. O. oeni was the species responsible for the occurrence of spontaneous MLF in most of the commercial base wines. Lb. brevis, Lb. hi/gardii and Lb. paracasei were also isolated from commercial base wines that had undergone spontaneous MLF. In nine out of 14 experimental base wine samples that had undergone spontaneous MLF, O. oeni was again the predominant species. Lb. brevis, Lb. hi/gardii and Lb. paracasei were identified in the remaining experimental base wine samples. This is the first report of the presence of Lb. perecese! and Lb. vermiforme in brandy base wine. It was shown that the occurrence of spontaneous MLF had a negative effect on the quality of brandy base wine, but that was shown to be due to the different species and strains performing MLF. In the non-preferred distillate samples, Lactobacillus spp. had performed MLF or had developed after or during MLF.
AFRIKAANSE OPSOMMING: Die teenwoordigheid en die vermoë van melksuurbakterieë (MSB) om in wyn te groei, is 'n onderwerp wat al heelwat nagevors is. Melksuurbakterieë is verantwoordelik vir die uitvoering van appelmelksuurgisting (AMG) in wyn. Die voordele verbonde aan appelmelksuurgisting, ten opsigte van die verlaging van die totale suurinhoud en die bydrae tot die verbeterde geur en kompleksiteit van die wyn, is ook al goed bestudeer. Wat die invloed op die finale wynkwaliteit betref, is dit byna onmoontlik om AMG as uitsluitlik gewens óf ongewens te beskou. Die voordele en nadele van AMG is afhanklik van verskeie faktore, nl. wingerdkundige streek, druifkultivar, wynsamestelling, wynmaakpraktyke, asook die styl en doelwitte van die wynmaker. Die produksie van brandewyn is 'n multistapproses waarin die bereidingsmetode van die basiswyn, die distillasietegniek en houtveroudering 'n groot invloed op die finale kwaliteit en chemiese samestelling van die brandewyn het. Die vlugtige verbindings van die basiswyn, wat tydens die dubbele distillasieproses gekonsentreer word, is van wesenlike belang in die bepaling van die aroma en geur van die finale brandewynproduk. Brandewyn is dus inderdaad net so goed soos die basiswyn waarvan dit gestook is. Die doelwitte van hierdie studie was om te bepaal wat die invloed van MSB en die voorkoms van spontane AMG op die kwaliteit van die basiswyn en die distillaat is, asook om die MSB wat vir die voorkoms van spontane AMG verantwoordelik was, te identifiseer. Hierdie studie het bewys dat MSB in hoë getalle teenwoordig was en dat dit in staat is om die spontane AMG van basiswyne uit te voer. Daar is bewys dat die voorkoms van spontaneAMG moontlik van jaar tot jaar kan verskil. In 1998 het 50%, in 1999 het 34% en in 2000 45% van die kommersieel-geproduseerde basiswyn gedeeltelike AMG spontaan voor distillasie ondergaan. Daar is ook gevind dat spontane AMG 'n invloed op die chemiese samestelling en sensoriese kwaliteit van die basiswyn en die distillaat gehad het. Daar was 'n toename in die konsentrasies van etiellaktaat, asynsuur en diëtielsuksinaat in monsters wat spontane AMG ondergaan het. In dieselfde monsters was daar ook 'n afname in die konsentrasies van iso-amielasetaat, etielasetaat, etielkaproaat, heksielasetaat en 2-fenielasetaat. Sensoriese evaluering van die basiswyne en distillate het getoon dat daar betekenisvolle verskille was tussen die monsters wat AMG ondergaan het en dié wat nie AMG ondergaan het nie. Daar is bewys dat die distillate wat nie AMG ondergaan het nie, 'n beter aromaprofiel gehad het as dié wat AMG ondergaan het. Soet geure, soos sjokolade en karamel, en negatiewe geure, soos "chemies" en "oplosmiddel", was prominent in distillate wat AMG ondergaan het. Kruidagtige en vrugtige geure was meer intensief in distillate wat nie AMG ondergaan het nie. Vier-en-vyftig bakteriese rasse, almal Gram-positief en katalase-negatief, is gedurende die verskillende stadia van brandewynproduksie geïsoleer. Sewe rasse is uit druiwesap, 15 rasse gedurende die alkoholiese fermentasie, 20 rasse gedurende AMG en 12 rasse na voltooiing van AMG geïsoleer. Op die basis van koolstofdioksied (C02)-produksie vanaf glukose en glukonaat is 17 rasse as fakultatief heterofermentatief en 37 rasse as obligaat heterofermentatief geklassifiseer. Vyftien van die 37 obligaat-heterofermentatiewe rasse was staafvormig en is as lactobacilli geïdentifiseer. Die oorblywende 22 het ovaal of kokkus-bacillusvormige selmorfologie getoon. Identifikasie tot op spesievlak is gedoen deur van numeriese analise van die totale oplosbare selproteïenprofiele, 16S-rRNAvolgordebepalings en spesie-spesifieke inleiers vir die polimerasekettingreaksie (PKR) gebruik te maak. Die fakultatief-heterofermentatiewe rasse is as Lactobacillus paracasei en Lactobacillus p/antarum geklassifiseer. Die 15 obligaat heterofermentatiewe stafies is as Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus hi/gardii en Lactobacillus vermiforme geïdentifiseer. Die 22 ovaal, obligaat heterofermentatiewe isolate kon in twee groepe ingedeel word en is as Oenococcus oeni geïdentifiseer. Daar is bevind dat O. oeni-isolate vir die voorkoms van spontane AMG in die meeste van die kommersiêle basiswyne verantwoordelik was. Lb. brevis, Lb. hi/gardii en Lb. paracasei is ook uit kommersiêle basiswyne wat spontane AMG ondergaan het, geïsoleer. In nege uit 14 van die eksperimentele basiswyne wat spontane AMG ondergaan het, was O. oeni die dominante spesie. In die oorblywende eksperimentele wyne is Lb. brevis, Lb. hi/gardii en Lb. paracasei aangetref. Hierdie is die eerste vermelding van die teenwoordigheid van Lb. paracasei and Lb. vermiforrne in brandewynbasiswyn. Daar is gevind dat die voorkoms van spontane AMG "n negatiewe invloed op brandewynkwaliteit het, maar dit is as gevolg van die verskeidenheid van MSB-spesies en rasse wat voorkom. In die distillate wat deur die proepaneel afgekeur is, het Lactobacillus spesies die AMG deurgevoer, of het dit tydens of na AMG ontwikkel.

Malolactic fermentation (MLF) is an important process in the wine production. MLF results from the metabolism of certain lactic acid bacteria (LAB) and consists in the conversion of malate to lactate and CO2. Except deacidification, MLF can improve the quality and microbiological stability of the wines. The aim of this project was to investigate the preservation and utilization of the LAB with particular reference to the MLF. In order to measure the effect of various preservation methods and their productivity, an assay of cell vitality was developed. This measured the capacity to overcome and recover from freezing and freeze-drying. It was shown that this method was easily used and reliable. The effect of cultural conditions on the cryotolerance and vitality of the LAB was investigated, including: (1) the growth phase, (2) the growth temperature, (3) the medium pH, (4) composition of the medium, and (5) preincubation conditions. The optimal cultural conditions to obtain higher vitality after freezing varied with the species of LAB. When the pH of culture medium was controlled at pH 5 the LAB attained the highest vitality after freezing. When L. plantarum was preincubated in 5g/l yeast extract solution at 25°C for 1 hour, the survival rate of L. plantarum greatly increased, from 5.2% to 46.5%. The conditions of freeze-drying of the LAB were investigated. It was found that 4% yeast extract was the most effective protectant for L. plantarum and L. brevis and 5% glutamate were the best protectant for O. oeni. When the LAB was frozen quickly at -65°C, the vitality obtained was higher than those frozen slowly at -20°C after freeze-drying. Another factor to be considered important was ethanol tolerance when the freeze-dried malolactic bacteria were used in wines. Among the suspension media tested, 5% glutamate and 10% sucrose were the best for freeze-dried L. brevis and O. oeni respectively to obtain high vitality in high ethanol solutions. These studies showed that there were no consistent underlying processes that could be easily identified and that preservation was a species specific, multifactorial process. The MLF was then investigated further by studying the effect of wine components on the batch MLF of L. brevis and O. oeni using a defined synthetic wine. This uniquely allowed a systematic study of the MLF in high alcohol environments. Alcohol tolerance was dependent on temperature and important fermentation intermediates such as citrate, pyruvate and malate. Malolactic fermentations were inhibited when glucose concentration was 2 g/1 to 6 g/1. The inhibition to MLF of O. oeni caused by glucose was relieved when fructose was present. Nutritional status was also an important factor that affected the MLF, when the synthetic wine did not contain added yeast extract, malic acid degradation of L brevis and O. oeni was low (6.1% and 54.3% respectively). Rapid and continuous malolactic fermentation was achieved in the membrane bioreactor (MBR) with high cell density of O. oeni (greater than 108CFU/ml). More than 95% degradation of malic acid in the synthetic wine was obtained at 0.48 1/h of flow rate and 10.4 h residence time. High ethanol concentration of wine was main factor that caused the loss in malic acid degrading activity of O. oeni in the MBR. The poor nutritional condition of wine was not the main factor causing loss in the stability of malic acid degrading activity of O. oeni. The shear stress had little influence on the malic acid degradation of O. oeni under the conditions investigated. Ethanol stress adaptation could improve the stability of malic acid degrading activity of O. oeni in the MBR.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第11617号
農博第1473号
新制||農||905(附属図書館)
学位論文||H17||N4010(農学部図書室)
UT51-2005-D366
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 清水 昌, 教授 加藤 暢夫, 教授 植田 充美
学位規則第4条第1項該当

Certaines bactéries lactiques (BL) peuvent se développer pendant le stockage des viandes et inhiber des bactéries pathogènes ou d’altération qui sont un problème dans l’industrie des produits carnés. Plusieurs mécanismes sont alors mis en jeu comme une compétition générale et/ou la production de molécules inhibitrices comme les bactériocines. Dans cette thèse, 198 souches de BL ont été testées pour leur capacité à inhiber des espèces d’altération (Brochothrix thermosphacta, Clostridium estertheticum) ou pathogènes (Listéria monocygènes, Campylobacter jejuni) susceptibles de se développer sur la viande. Parmi 7 isolats capables d’être compétitifs dans des conditions de laboratoire, 3 souches de Lactobacillus sakei et 1 souche de Carnobacterium maltaromaticum se sont avérées également efficaces vis-à-vis de certaines espèces indésirables après inoculation de viande de mouton ou de bœuf, sans affecter la qualité sensorielle des produits. En effet, la croissance de ces souches de BL était associée à l’inhibition du développement de L. Monocytogènes et C. Jejuni et à la réduction de production de gaz par C. Estertheticum. L’analyse des produits sensoriels et altérants de viande de mouton inoculée par un cocktail de 3 souches de L. Sakei à montré une augmentation de la qualité d’acides lactique et acétique et une diminution de pH n’affectant pas l’acceptabilité sensorielle de la viande. Les résultats de cette étude ont permis la caractérisation d’une collection de BL, essentiellement composée de L. Sakei pouvant servir de base pour le développement d’outils utiles à la bio-conservation de viande réfrigérée Néozélandaise destinée à l’exportation
Some lactic acid bacteria (LAB) are capable or growing on stored meat and inhibiting pathogenic and spoilage bactéria of concern to the meat industry using a range of mechanisms including general competition and/or the production of specific inhibitory molecules such as bacteriocins. In this thesis, 198 LAB strains were screened for their ability to inhibit spoilage species (Brochothrix thermophacta, Clostridium estertheticum) or pathogenic species (Listeria monocytogenes, Campylobacter jejuni) that can occur on meat. Out of 7 isolates able to compete in laboratory conditions, 3 Lactobacillus sakei and 1 Carnobacterium maltaromaticum strains were shown to be also efficient against some undesired species when seeded in lamb or beef meat, without affecting the sensory quality of the products. Indeed growth of the LAB strains was associated to the inhibition of L. Monoctytogenes and C. Jejuni and a reduction of gas production by C. Estertheticum. Sensory and spoilage product analysis of stored lamb inoculated with a 3-strain cocktail of L. Sakei showed higher levels of lactic and acetic acids and a lower pH without affecting the sensory acceptance of meat. The results of this work characterize a collection of predominantly L. Sakei LAB strains that may provide the basis for developing useful products for the bio-preservation of chilled New-Zeland export meat

Probiotics are marketed throughout the world to promote the health of the consumer by improving the microorganisms that normally occur in the intestinal tract (Tannock, 1997). It has also been suggested that probiotics can prevent pathogen infections by adhering to the intestinal mucosa (Lee, Lim, Teng, Ouwehand, Tuomola, & Salminen, 2000). While probiotics can be delivered to the infected areas in multiple fashions, microencapsulation is a newer form of delivering probiotics straight to the infected area. A whey protein microcapsule is thought to protect the probiotics from stomach acid and delivers the treatment to the affected area. To ensure this microencapsulation treatment is affective, the microcapsules will be stained and imaged to see if the microcapsules are constructed in a way which is consistent with the theory: a whey protein microcapsule surrounding bacteria and fat droplets. Through these experiments, it was shown that the microcapsule was not constructed as previously thought. Instead of a thin layer of protein surrounding the bacteria, it more closely resembled a solid ball of protein with bacteria and fat trapped inside. The bacteria are able to survive stomach like conditions (0.1M HCl for 8 hours) due to other forms of microencapsulation.

Food fermentation is a method widely used in the past to extend the storage life of food. Numerous studies on fermented food have revealed that they not only have biopreservative properties but also health benefits. Lactic acid bacteria are the major group of microorganisms involved in food fermentation and the properties that influence food are primarily due to the compounds released from microorganisms such as organic acids and bacteriocins. Their health benefits are exerted through several mechanisms including inhibiting the growth of pathogenic bacteria and modifying the host immune response. A number of strains that have been investigated show different properties even between the same species thus emphasizing the importance of strain identification. To determine if some traditional fermented Swedish foods contain lactic acid bacteria, bacteria from four fermented Swedish foods (two surströmming and two sausages) were isolated using MRS broth. Bacterial isolates were examined for their colony and cell morphology and Gram staining and were found to be predominantly Gram-positive cocci or rods. 16S rRNA PCR amplifications of selected isolates was performed using universal prokaryotic primers and sequenced. The sequencing results showed that the bacterial isolates from Oskars surströmming Filéer and Gognacs medvurst were Lactobacillus sakei and the isolate from Mannerströms surströmming was Enterococcus sp. This study showed that the traditional Swedish fermented food evaluated did contain lactic acid bacteria.

Lactic acid bacteria (LAB) were isolated during the production and the ripening of Greek dry fermented sausages. Samples were taken at different stages, and 150 "wild' strains were isolated. The majority of the strains isolated were assigned to the species Lactobacillus plantarum biotype (1) (43.3 %) followed by Lb. curvatus, Lb. pentosus (10.7 %), Lb. brevis biotype (1) (8.7 %), Lactococcus lactis subsp. lactis biotype (1) (6.7 %) and Leuconostoc mesenteroides subsp. mesenteroid.es biotype (2) (5.3 %). The possibility of bacteriocin production was tested using the agar well diffusion assay (AWDA). One strain was found to produce bacteriocin (Leuconostoc mesenteroides E131) and its purification was attempted using precipitation with ammonium sulphate, cation exchange, and reverse phase chromatography. Moreover, the purification of curvaticin L442 was attemped, a bacteriocin produced by Lactobacillus curvatus L442, isolated from Greek traditional fermented sausage prepared without addition of starters. The bacteriocin was purified by 50% ammonium sulphate precipitation, cation exchange, reverse phase and gel filtration chromatography. Lb sakei I154, a bacteriocin producing strain isolated from Italian fermented sausage, and the semi-purified bacteriocin from Leuconostoc mesenteroides E131 were validated via industrial trials to evaluate whether the product (fermented sausages) maintains the technological characteristics and the traditional quality characteristics. Three fermentations under controlled conditions were conducted and at the end of these fermentations, products were sliced and packaged under controlled atmosphere (80% N2 + 20% CO2) and stored at 4+/-2 °C for 12 weeks to determine the shelf life of the product. Finally, from the previous industrial trials the proper production parameters were determined as well as the most effective packaging techniques, resulting in the conduction of a Standard Operation Procedures Guide concerning the whole production of traditional fermented sausages.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第19046号
農博第2124号
新制||農||1032(附属図書館)
学位論文||H27||N4928(農学部図書室)
31997
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 小川 順, 教授 加納 健司, 教授 植田 充美
学位規則第4条第1項該当

Tese de doutoramento em Engenharia Química e Biológica
Lactic acid bacteria (LAB) are frequently used in fermentation processes and have been gaining attention in biopreservation approaches against fungal contaminations. Fungal contaminations can be responsible for health issues, and economic losses since several species produce toxic compounds named mycotoxins. Mycotoxins can cause several organs diseases and cancer. In this work, cell-free supernatant (CFS) of the Lactobacillus plantarum UM55 strain demonstrated the ability to reduce Aspergillus flavus growth by 32% and aflatoxin production by 91%. Additionally, this strain CFS and the CFS from strain Lactobacillus buchneri UTAD104 inhibited radial growth of Penicillium nordicum by 17% and Ochratoxin A (OTA) production by 60%. These inhibitions resulted from organic acids produced by LAB. CFS of L. plantarum UM55 contained lactic acid, phenyllactic acid (PLA), hydroxyphenyllactic acid (OH-PLA) and indole lactic acid (ILA), while CFS of L. buchneri UTAD104 had acetic acid, lactic acid, and PLA. These compounds were individually tested against A. flavus and P. nordicum, with all showing an inhibiting effect on fungal growth and mycotoxin production. PLA and acetic acid were the most effective inhibiting A. flavus and P. nordicum, respectively. When the inhibitory activity of LAB cells incorporated into an agar culture medium was tested, L. buchneri UTAD104 inhibited the production of OTA entirely in all conditions tested, with acetic acid being the main responsible for this effect. L. buchneri UTAD104 was further incorporated into edible films and coatings to prevent fungal contamination in cheese. Films containing the bacteria, maintained their physicochemical, mechanical and barrier properties when compared with control films. These films completely inhibited the growth of P. nordicum on the surface of cheese samples, resulting in the absence of OTA in the samples. Some LAB strains are definitely capable of controlling mycotoxigenic fungi. The antifungal ability of these strains is mainly due to the production of organic acids. LAB strains can be incorporated into edible films and coatings for the control of mycotoxigenic fungi in cheese products.
As bactérias do ácido láctico (BAL) são extensivamente usadas em processos de fermentação e têm suscitado interesse em abordagens de biopreservação para o controlo de fungos. As contaminações fúngicas podem originar problemas de saúde e avultadas perdas económicas. Algumas espécies de fungos podem, ainda, produzir compostos altamente tóxicos denominados de micotoxinas. As micotoxinas podem originar várias doenças em órgãos internos e provocar cancro. Neste trabalho, verificou-se que os sobrenadantes da estirpe Lactobacillus plantarum UM55 reduziram o crescimento do fungo Aspergillus flavus em 32% e a produção de aflatoxinas em 91%. O sobrenadante desta estirpe e da estirpe Lactobacillus buchneri UTAD104 mostraram também inibir o crescimento radial de Penicillium nordicum em 17% e a produção de ocratoxina A (OTA) em 60%. Estas inibições resultam da produção de ácidos orgânicos por partes destas estirpes. Foi detetada a presença dos ácidos lático, fenil-lático, hidroxifenil-lático e índole lático nos sobrenadantes de L. plantarum UM55 e dos ácidos acético, lático e fenil-lático nos sobrenadantes de L. buchneri UTAD104. Estes compostos foram testados individualmente contra A. flavus e P. nordicum, e todos inibiram o crescimento fúngico e a produção de micotoxinas. O ácido fenil-lático e acético foram os mais eficazes na inibição de A. flavus e P. nordicum, respetivamente. Testes com BAL incorporadas no meio de cultura demonstraram que L. buchneri UTAD104 suprimiu a produção de OTA em todas as condições testadas, sendo o ácido acético o principal responsável por este efeito. Esta estirpe foi incorporada em filmes e revestimentos edíveis com o objetivo de eliminar fungos no queijo. Testes aos filmes com incorporação de BAL, mostraram que estes filmes mantiveram as suas propriedades físico-químicas, mecânicas e de barreira, quando comparados com os filmes de controlo. Estes filmes inibiram completamente o crescimento de P. nordicum na superfície do queijo resultando na ausência de OTA nas amostras. Este trabalho demonstrou que algumas BAL podem ser utilizadas para controlar fungos micotoxigénicos. A capacidade antifúngica destas estirpes é devida, maioritariamente, à produção de ácidos orgânicos. As BAL podem ser incorporadas em filmes e revestimentos edíveis para controlar fungos micotoxigénicos em queijos.
The work presented in this thesis was performed in the Centre of Biological Engineering (CEB), Minho University. Financial support was provided by the Portuguese Foundation for Science and Technology (FCT) through a research grant SFRH/BD/103245/2014. This study was also supported by the FCT under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.

博士
大同大學
生物工程學系(所)
96
The results are divided into two parts with screen of probiotic Lactic acid bacteria and constructing shuttle vector of Lactic acid bacteria. In part I, the probiotic Lactic acid bacteria (LAB) was screened and used for provide intestinal health and host of shuttle vector of LAB. In part II, a cryptic LAB plasmid was isolated and the plasmid sequence was determined. Based on LAB plasmid, a shuttle vector was constructed, it could maintain stably in probiotic LAB and express heterologous protein gene. In screen of probiotic LAB, the twenty-one of LAB strains which could withstand high acid and bile salt conditions were selected. These strains meanwhile could tolerate digestive system, restrain pathogenic bacteria growth, metabolize isomaltooligosaccharides and gentiooligosaccharides, and induce cytokine production (IL-12 p40p70 and IL-10) by RAW 264.7 macrophage cell. All of these strains could be used as a candidate for probiotics. The species were identified as Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, and Lactobacillus rhamnosus by API and 16S rRNA. Strain E1, E33, E40, and E55 were plasmid free and selected as the host of shuttle vector system of LAB. In constructing shuttle vector of LAB, a cryptic plasmid pL2 was isolated from Lactococcus lactis subsp. lactis and its complete nucleotide sequence was determined (5,299-bp, GenBank accession No. DQ917780). Its replication mode was identified as a theta-type belonging to the pAMβ1 family. Analysis of the nucleotide sequence revealed that pL2 contained a transfer origin, a replication origin, and five putative open reading frames (ORF 1-5). ORF1 (386 amino acids) was homologous to replication protein RepB. The shuttle vector pUL6erm was constructed by using a replicon from pL2, a multiple cloning site, colE1 ori, the origin of Gram-negative bacteria from vector pUC19, and the erythromycin resistance gene from pVA838 as a selective marker. The pUL6erm could be transformed easily and maintained stably in E. coli, Lactobacillus casei, Lactobacillus plantarum, Lactococcus lactis, and Streptococcus thermophilus. The expression plasmid pUL6erm- gadR-GUS was constructed base on pUL6erm and a chloride-inducible gene expression cassette encoding gadR and the Pgad promoter. Growth in the presence of 0.3 M sodium chloride and 50 mM glutmate, the beta-D-glucuronidase was induced and expressed with 2.37 Unit/mg by plasmid pUL6erm-gadR-GUS.

碩士
國立中興大學
食品科學系
86
Nineteen strains of lactic acid bacteria including Bifidobacterium longum B6 and 15708, Lactobacillus acidophilus B, E, Farr, LA-1, N-1, and 4356, Lactobacillus bulgaricus Lb, 448, 449, 1006, 11842, and 12278, and Streptococcus thermophilus MC, 573, 821, 3641, and 19987 were investigated for cholesterol reducing ability in vitro. Most of the strains tested were able to reduce cholesterol. L. bulgaricus 449 demonstrated the best cholesterol reducing ability when oxgall was present. L. acidophilus 4356 also reduced cholesterol very well when oxgall was used. These two strains reduced cholesterol at 51 and 41 %, respectively. No particular genus or species showed higher cholesterol reducing ability than the others. The mechanisms of cholesterol reduction were also identified in the in vitro system. Although the coprecipitation of cholesterol with deconjugated biles contributed to the reduction of cholesterol levels, cholesterol was reduced when taurocholic acid was used as the source of bile. Therefore, the cholesterol reduction in the presence of bile does not attribute only to the coprecipitation with deconjugated bile salts but also to the assimilation by cells.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1994.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 184-215).

Dissertação de mestrado em Bioinformática
Biotechnology plays an essential role in the modern industry and in guaranteeing sustainable future for humankind. Advances of metabolic engineering and systems biology allow the adaption of complex cellular networks for the production or uptake of certain molecules, with great economical interest, enabling the creation of cell factories. Among the potential microorganisms that fit this role is the well-known group, due to their role in food fermentation and, in particular, their use in dairy industry, known as Lactic acid bacteria (LAB). Their metabolism is known for its relative simplicity and lack of biosynthesis capacity, creating a potential application as a cell factory in transformation processes. The purpose of this work is to develop through evolutionary engineering a strain of LAB capable of utilizing mannitol as the sole carbon source and identify mutations in the evolved strain, with the objective of associate these mutations with the mannitol consuming phenotype. Through the usage of adaptive laboratory evolution (ALE), several strains of LAB were evolved and a selected evolved strain of Lactococcus lactis subsp cremoris, capable of consuming mannitol as the sole carbon source successfully, was sequenced using next-generation sequencing. From the analysis of this genomic data using several bioinformatics tools available, 3 mutations affecting the genes pta, adhA and mtlF were identified as likely having an impact in the new phenotype presented by the evolved strain. This work provides an initial inquiry into a potential application of brown algae, which accumulate mannitol, as a new feedstock for biofuel production using LAB as cell factories.
A Biotecnologia tem assumido um papel preponderante nos processos industriais da atualidade, tendo em vista a conjugação destes com a questão da sustentabilidade da espécie humana. Os avanços na engenharia metabólica e na biologia de sistemas tem permitido a adaptação das complexas redes celulares, com o intuito de produzir ou consumir certos compostos, de forma a aumentar o seu valor económico, criando ‘fábricas celulares’. Entre os potenciais organismos para este tipo de aplicação encontra-se um grupo bastante conhecido devido à sua função na fermentação de certos alimentos, especialmente lacticínios, denominadas bactérias ácido-lácticas. Estas possuem um metabolismo relativamente simples e não apresentam várias capacidades biossintécticas, tornando-as em potenciais candidatas a serem usadas como ‘fábricas celulares’ em processos de transformação. Neste trabalho pretende-se adaptar através de engenharia evolutiva várias espécies de bactérias ácido-lácticas à utilização de manitol como fonte de carbono e proceder à identificação de mutações no genoma das estirpes evoluídas através de tecnologias de sequenciação de ADN, com o propósito de relacionar estas mutações com o fenótipo capaz de consumir manitol. Com recurso à engenharia evolutiva, várias estirpes de bactérias ácido-lácticas foram evoluídas e uma dessas estirpes, Lactococcus lactis subsp cremoris, capaz de consumir manitol como a única fonte de carbono, foi selecionada para ser sequenciada com recurso tecnologias de sequenciação de ADN. Através da análise destes dados genómicos usando várias ferramentas bioinformáticas, foi possível determinar 3 mutações que afectam os genes pta, adhA e mtlF que possivelmente estarão relacionadas com o fenótipo exibido pelas espécies evoluídas. Este trabalho serve como uma avaliação ao potencial da utilização de algas castanhas, que acumulam manitol, como um novo recurso para a produção de biocombustíveis, usando bactérias ácido-lácticas como ‘fábricas celulares’ para a sua transformação.

碩士
國立中興大學
食品科學系
92
The stimulatory effect of eight strains of lactic acid bacteria including L. acidophilus 4356, L. acidophilus LA-1, L. bulgaricus 448, L. bulgaricus 449, B. longum B6, B. longum 15708, S. thermophilus MC and S. thermophilus 573 on murine macrophage J774A.1 cell line were examined. The fractions of lactic acid bacteria including viable bacteria, heat-killed bacteria, intracellular extract, extracellular extract, crude cell wall, chromosome DNA, and whey of fermented milk were used for this study. The testing items include proliferation, the secretion of TNF-α and IL-6, and phagocytosis of murine macrophage J774A.1 cell line. The result showed that lactic acid bacteria activate the macrophages proliferation by 107 cfu/ml of viable bacteria, fermented milk and 0.05 μg/ml of genomic DNA, respectively. And the degree depended on the difference of strains and numbers of bacterium. Co-culture with 1,000 and 100 μg/ml crude cell wall extract or whey of fermented milk which containing 106-108 cfu/ml lactic acid bacteria with macrophage cell line significantly increased its production of TNF-α. Crude cell wall extracts (1,000 and 100 μg/ml) and viable bacteria (107 cfu/ml L. acidophilus LA-1, 107-108 cfu/ml, L. bulgaricus 448, 106-107 cfu/ml B. longum 15708 and S. thermophilus MC) could stimulate the production of IL-6 by macrophage cell line. Many fractions of lactic acid bacteria could stimulate phagocytosis of macrophage cell line, including heat-killed bacteria, intracellular extract, extracellular extract, genomic DNA and whey of fermented milk. Immunomodulatory activity of lactic acid bacteria depended on difference of strains and numbers of bacterium, and expressed strain-dependent manners. In our results also indicate that lactic acid bacteria can stimulate the macrophage cell line and may improve immune system, but not to such an extent as to inflammation.

碩士
中興大學
食品暨應用生物科技學系
95
Abstract The key technique of bread production is the improvement of flavor and storage time and the addition of lactic acid bacteria (LAB) to bread during the manufacturing process would help. In this study first screened LAB with the ability to leaven the sourdough and produce good flavor. Among the 16 tested strains, Lactobacillus delbrueckii delbrueckii (LDD) produced the most acidity and Pediococcus acidilactici (PA) produced the best flavor. We then used these two strains in toast making. LDD and PA were added into sourdough which was made to toast, and the proximate composition, physical parameters, taste quality, volatile components, bioactive components and sensory quality of toast were analyzed. Experiment results indicated that the lightness of the three toasts were in the descending order of LDD toast（71.20）>white toast（69.97）> PA toast（68.98）. X-ray diffraction revealed that the peak strength of the three toasts increased during the storage time. In a six-day storage experiment at 25℃, the hardness of the three toasts increased, while hardness, cohesiveness, gumminess, chewiness and resilience decreased with time. The LDD toast was the most abundant in nucleotides content (1.95 μg/g), following by white toast (1.11 μg/g) and PA toast (0.97 μg/g). Also, the LDD toast contained the most organic acid (4.07 mg/g) and PA toast (4.35 mg/g) following by white toast (3.10 mg/g). LDD toast contained the most kinds and quantity of aromas. In the six-day storage experiment, the total plate count of PA toast (3.20 log CFU/g) and LDD toast (46 log CFU/g) were significantly lower than white toast (7.85 log CFU/g) (p＜0.05). With regard to the hedonic scores in sensory evaluation, LDD toast and PA toast were more accepted than white toast in flavor and mouth feel. In a summary, the addition of LDD to toast enhanced the palatable taste and sweet taste, and thus improved the flavor and nutritional value of toast.

碩士
中國醫藥大學
藥學系碩士班
97
Lactic acid bacteria isolated from soil, plants, fermented dairy products, animal feces or human feces are considered to be probiotics with therapeutic and healthy properties; however, the effectiveness of probiotics can be affected by manufacturing processes, such as freeze-drying or spray-drying. The purpose of this study was to develop a technique for microencapsulation of probiotics that can protect probiotics during the freeze-drying process. The formulations(A-MsP) of alginate (3%) with 3% skim milk powder, and 2% peptone were prepared. The effect of the cryoprotectants on cell survival during freeze-drying was investigated using a standardized amount of cells and the optimized freeze drying media. The results showed that this formulation (A-MsP) provided sufficient protection for probiotics, resulting in probiotic counts of up to 1011 CFU/g after freeze-drying. The survival of microencapsulated L. rhamnosus was better than free cell at low pH. The release of encapsulated cells in simulated aqueous solution of colonic pH was also assessed. However, this formulation (A-MsP) needs to be improved if we want to apply microencapsulation to spray-dry. The microencapsulated lactic acid bacteria maintain their survival at 4℃ during a 6 week period. This probiotic microencapsule can potentially be used in fermented dairy products and healthy food products or as a drug delivery system in the future.

碩士
國立臺灣海洋大學
食品科學系
102
gamma-Aminobutyric acid (GABA) is a well-known non-protein amino acid, which is widely distributed in animals and plants. GABA has been reported to be a major inhibitory neurotransmitter in the mammalian central nervous system and show antihypertensive activity. This aims of this research are to manufacture a GABA-enriched fermented milk by lactic acid bacteria (LAB) isolated from fish intestines and to evaluate the probiotic potential property of the GABA-producing LAB. Preliminarily, lactic acid bacteria strains were isolated from healthy fish intestine from previous study. Ten lactic acid bacteria strains of 126 LAB strains were screened based on the capacity of synthesizing GABA. And ten GABA-producing strains show that none of them exhibited hemolytic activity. Moreover, five strains exhibited partial bile salt hydrolase activity, including the strain FPS 2520. FPS 2520 also showed a high percentage of adhesion to monolayer of Caco-2 cells. Strain FPS 2520 demonstrated high survival viability to gastrointestinal conditions simulating stomach and duodenum passage. Optimal conditions of strain FPS 2520 for producing GABA in whole milk were: 10% reconstituted whole milk, initial inoculum size of 5 log CFU/mL, addition of 20 mM MSG, 1% brown sugar, and 0.5% yeast extract during fermentation at 37oC for 48 hours. The results indicated FPS 2520 show a probiotic potential property and have a great application in milk fermentation for the production of G (10.67 mg/mL), and the IC50 of ACEI-inhibitory activity is 0.28 ± 0.02 mg/mL. Besides lactic acid bacteria number slightly decreased, pH value, titratable acidity and GABA concentration didn’t have significant difference compare to control at 4oC for 14 days. Using mixed strains, GABA-producing strain FPS 2520 and proteinase-positive FKR 3737 could significantly enhance the GABA production about 14.74 mg/mL.

博士
國立中興大學
食品科學系
91
Banana was used as the raw material for the preparation of fermentation media of Lactobacillus acidophilus, and cell immobilization was applied to improve the fermentation efficiency of L. acidophilus in banana media. Cell immobilization was performed using calcium alginate and κ-carrageenan as the entrapping matrix, and gel beads of diameters around 2.6 mm for the former and 3.0 mm for the latter were obtained. Both green and ripe bananas were used for the preparation of banana media, and both free and immobilized cells were used to conduct the fermentation for 80 hours. The viable cell number in ripe banana media was found to be higher than that in green ones during both free cell and immobilized cell fermentation. During the fermentation of immobilized cell, cells would leak out from the gel beads and grew in the medium solution. In immobilized cell fermentation, the final viable cell number could reach 105 CFU/ml in medium suspension and that in gel beads could become over 108 CFU/ml gel. In free cell fermentation, the final viable cell number was around 106 CFU/ml. Immobilized cell could overcome the unfavorable conditions in green banana media and improved results could be obtained. During the fermentation, the variation of pH and titratable acidity showed obvious relationships with the growth of cells. Variation of fructooligosaccharides contents in ripe banana media was not remarkable in immobilized cell fermentation compared to free cell. Immobilized L. acidophilus fermented banana medium was able to be used as a synbiotic product by combining the probiotic effect of L. acidophilus and the prebiotic effect of banana. The effect of Ca-alginate immobilization was better than κ-carrageenan. Based on the overall results of cost analysis, Ca-alginate immobilization was a better choice compared toκ-carrageenan immobilization. On the other hand, L. acidophilus was immobilized using Ca-alginate andκ-carrageenan, and protection effects of cell immobilization on the viability of the bacteria after freezing and freeze-drying were studied, and its influence on the storage stability of the freeze-dried cells at 5℃, 25℃, 45℃, 60℃, 70℃ was also investigated. Initial concentration of both free and immobilized cells used for experiments all reached the level of 1010 cells/ml. Results indicated that the immobilization in Ca-alginate gel beads andκ-carrageenan gel beads could provide effective protection to reduce the damage of bacteria under operations. High correlations were obtained between Log D values and storage temperatures for both free and immobilized cells under those various storage temperatures used. the z value which derived from the linear regression equation of Log D and storage temperature for free and immobilized cells were significantly different (p < 0.05). Cell immobilization could enhance temperature tolerance of the freeze-dried bacteria during storage and diminish the influence of temperature variation on the storage stability of freeze-dried cells.

碩士
中華醫事科技大學
生物醫學研究所
100
Diabetes has become a global disease, which is accompanied by complex complications, reinforce the seriousness of diabetes, so in terms of treatment and prevention, has become urgent and important research topic. Health Department announces 2010 citizens 10 leading causes of death, diabetes has been highest in the fifth of the ten major causes of death, and the proportion of men and women. Diabetes is a will effect multiple organ of metabolism sexual disease, and is high medical spent of disease, long-term complications including retinal lesions and has potential occurs blind of dangerous, and kidney lesions caused kidney function failure, and perimeter neuropathy variable and has foot Department ulcer and amputation of dangerous and the neural sexual joint disease, and independent neuropathy variable caused stomach, and reproductive urinary and cardiovascular symptoms and the sexual function obstacles,, are will on patients and family caused psychological and social function of impact. Currently on the clinical treatment of diabetes complications are mainly controlled condition deteriorated and reduce complications, however traditional drug therapy is often limited, and is prone to side effects, so diet is the most natural method, it aims to make blood sugar close to normal values, and the maintenance of blood fat and cholesterol of normal, and achieve the goal of normal weight. In the past, many studies pointed out that the lactic acid bacteria to decrease blood lipids, lowering blood sugar, lowering blood pressure, and activation of the immune system and other effects. Therefore, if the use of lactic acid bacteria supplements, believe, will help relieve or prevent the symptoms of some of the complications of diabetes and incidence for complications of diabetes, kidney disease, cardiovascular and cerebral vascular disease, dental complications, this study and discussion, that the effectiveness of lactic acid bacteria, their symptoms improve or prevent.

碩士
輔英科技大學
保健營養系碩士班
102
There are many human gut microbes in many physiological and metabolic processes which produce a host of health products. The conjugated linoleic acid is one of a host of health benefits products. However, their ability to generate different conjugated linoleic acids is uncertain. In this study, we selected two strains of lactic acid bacteria Lactobacillus fermentum Fy-003 and Enterococcus faecalis Fy-004 performing conjugated linoleic acids generation capacity from the intestine of newborns. We used sunflower oil supplement for analysis conducted in conjugated linoleic acid generation and found that the producing ability that great potential. Fy-003 produced trans-9, trans-11 isomer 146.46 ppm and Fy-004 produced trans-10, cis-12 isomer 130.27 ppm. At the same time, we found sunflower oil supplement to increase the concentration of lactic acid may drop production.