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Pradhan, Nirakar. "Hydrogen and lactic acid synthesis through capnophilic lactic fermentation by Thermotoga neapolitana." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1145/document.
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Les énergies non-renouvelables ont été d’un apport capital dans l’industrialisation et l’urbanisation dans les derniers centenaires. L’exploitation excessive des réserves d’hydrocarbures et son impact environnemental ont contribué au developpement de plusieurs technologies durables à caractère néo-carbone neutre. A cet effet, les processus biologiques comme la fermentation pourraient être exploités pour convertir biologiquement le hydrates de carbone en énergies comme l’hydrogène (H2) ou des acides organiques commercialement rentables. Ce travail a étudié les techniques d’ingénierie pour améliorer la synthèse simultanée d’H2 et d’acide lactique à travers des conditions de fermentation capnophile lactique (CLF) par une souche de labo de Thermotoga neapolitana.En un premier temps, une comparaison génotypique entre la souche de labo et celle sauvage a révélé une ressemblance de 88,1 (±2,4) %. En plus, les analyses du génotypage par RiboPrint® et par spectroscopie de masse matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) ont montré une différentiation génétique au-delà du niveau sous-espèce ; et par conséquent la souche de labo a été proposée comme sous-espèce, T. neapolitana subsp. lactica. Basé sur la caractérisation phénotypique, la souche de labo produisait 10-90% plus d’acide lactique que celle sauvage sous les mêmes conditions sans pour autant affecté le taux de production d’H2.La souche de labo a donc été étudiée pour aussi bien optimiser les conditions de croissance que pour estimer les paramètres cinétiques de croissance. Un nouveau modèle cinétique basé sur les principes de fermentation à l’obscurité (DF) et les expressions mathématiques Monod ont été développés pour permettre la simulation de la croissance en biomasse, la consommation de substrat, et la formation de produit. Le modèle n’a cependant pas pu faire une estimation des acides acétique et lactique avec précision du fait que le modèle DF n’a pas considéré la carboxylation de l’acide acétique en acide lactique par l’enzyme pyruvate ferrédoxine oxydoréductase (PFOR) sous les conditions CLF.Le model a été associé avec le mécanisme CLF et les paramètres cinétiques ont été recalibrés. Les paramètres cinétiques que sont le taux d’absorption spécifique maximum (k), la constante semi-saturation (ks), le coefficient en rendement biomasse (Y), et le taux de décomposition interne (kd) étaient de 1,30 l/h, 1,42 g/L, 0,12 et 0,02 l/h. Fait intéressant, le nouveau modèle CLF s’est parfaitement adapté avec les résultats expérimentaux et a estimé que près de 40-80% de la production d’acide lactique est attribué au recyclage de l’acide acétique et le CO2.En plus, l’adsorption de l’acide lactique par le carbone actif et les résines polymères anioniques a été appliquée avec succès comme technique de transformation en aval dans la récupération et la purification de l’acide lactique à partir du modèle de fermentation type T. neapolitana. Pour ce faire, ce travail de recherche constitue une étape majeure dans le domaine de la fermentation bactérienne utilisable pour de vastes applications scientifiques prenant en compte le développement d’énergies renouvelables et la production industrielle d’acide lactiqueThe environmental impact of excessive exploitation of fossil fuel reserves has inspired the innovation of several sustainable neo-carbon-neutral technologies. To that end, the biological processes like fermentation may be leveraged to bioconvert carbohydrate-rich feedstocks to fuels like hydrogen (H2) or commercially valuable organic acids like lactic acid. This research work investigated the engineering techniques for improving simultaneous synthesis of H2 and lactic acid under capnophilic (CO2-dependent) lactic fermentation (CLF) conditions by a lab strain of Thermotoga neapolitana.Primarily, the genotypic comparison between the lab strain and the wild-type revealed DNA homology of 88.1 (± 2.4)%. Genotyping by RiboPrint® and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses showed a genetic differentiation beyond subspecies level, hence the lab strain was proposed as a new subspecies, T. neapolitana subsp. lactica. The lab strain produced 10-90% more lactic acid, based on the phenotypic characterization, than the wild-type strain under similar operating conditions without impairing the H2 yield.The lab strain was then studied to optimize the growth conditions as well as to estimate the growth kinetic parameters. A new mathematical model based on the dark fermentation (DF) principles and Monod-like kinetic expressions was developed to enable the simulation of biomass growth, substrate consumption and product formation. The model failed to estimate acetic and lactic acid accurately, as the DF model did not consider the carboxylation of acetic acid to lactic acid by the pyruvate:ferredoxin oxidoreductase (PFOR) enzyme under CLF conditions. The model was then incorporated with the CLF mechanism and the kinetic parameters were recalibrated.The calibrated kinetic parameters, i.e. maximum specific uptake rate (k), semi-saturation constant (kS), biomass yield coefficient (Y) and endogenous decay rate (kd) were 1.30 1/h, 1.42 g/L, 0.12 and 0.02 1/h, respectively, under CLF conditions. The new CLF-based model fitted very well with the experimental results and estimated that about 40-80% of the lactic acid production is attributed to the recycling of acetic acid and CO2.In addition, the adsorption of lactic acid by activated carbon and anionic polymeric resins was successfully applied as a downstream processing technique for the recovery of lactic acid from a model T. neapolitana fermentation broth. This research work serves as a practical milestone in the field of microbial fermentation with a scope for wider scientific applications, including the development of bio-based renewable energy and industrial lactic acid production
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Khivasara, M. B. "Biomass to lactic acid: microbial cellulases and their application in cellulosic lactic acid production." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2015. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/1993.
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Wang, Peiyao. "Stereopure Functionalized Poly(lactic acid)." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366631276.
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Kanagachandran, Kanagasooriyam. "The physiology of lactic acid production by Lactococcus lactis IO-1." Thesis, University of Hertfordshire, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267963.
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Kishino, Shigenobu. "Production of conjugated fatty acids by lactic acid bacteria." Kyoto University, 2005. http://hdl.handle.net/2433/86244.
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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
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Magnusson, Jesper. "Antifungal activity of lactic acid bacteria /." Uppsala : Dept. of Microbiology, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a397.pdf.
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Oliveira, Juliana de. "Poly(Lactic acid) production by conventional and microwave polymerization of lactic acid produced in submerged fermentation." reponame:Repositório Institucional da UFPR, 2016. http://hdl.handle.net/1884/46421.
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Orientador : PhD. Luciana Porto de Souza VandenbergheCoorientadores : PhD. Carlos Ricardo Soccol e PhD. Sônia Faria Zawadzki
Tese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Bioprocessos e Biotecnologia. Defesa: Curitiba, 09/06/2016
Inclui referências : f. 115-128
Área de concentração: Agroindústria e biocombustíveis
Resumo: Poli(ácido lático), poliéster, é um polímero biodegravável aplicado em produtos como embalagens, têxteis, médicos e farmacêuticos. Pode ser obtido a partir do monômero ácido lático (AL) por meio da reação de policondensação direta e pela polimerização por abertura de anel do lactídeo. O AL é um ácido orgânico que apresenta diversas aplicações principalmente na indústria alimentícia, assim como na indústria farmacêutica, química e de polímeros. A produção do AL por fermentação oferece vantagens tais como a produção do isômero opticamente puro. As necessidades nutricionais da bactéria aumentam o custo de produção do AL, portanto substratos alternativos tem sido estudados por apresentarem uma alternativa econômica para este processo. O objetivo deste trabalho foi a produção de ácido lático por Lactobacillus pentosus em fermentação submersa utilizando subproduto do processamento da batata e caldo de cana como substratos para a obtenção de poli(ácido lático). Estes sub-produtos porque possuem alta concentração de fonte de carbono e volumes significativos são gerados anualmente, o que justifica sua a re-utilização e valorização. O sub-produto do processamento da batata foi submetido a hidrólise ácida com o objetivo de converter o amido em glucose. A produção de AL foi otimizada utilizando etapas de planejamento experimental estatístico envolvendo a seleção de bactérias do gênero Lactobacillus, definição da composição do meio de cultivo e estudos de cinética em frascos de Erlenmeyer e biorreator do tipo tanque agitado. A produção de AL chegou a 150 g/L utilizando sub-produto do processamento da batata e 225 g/L utilizando caldo de cana em 96 horas de fermentação. O uso da célula inteira de levedura de panificação como fonte de nitrogênio e a condição de fermentação não estéril demostraram ser boas alternativas para um processo industrial de produção de AL. O processo de separação e recuperação do AL do caldo fermentado foi desenvolvido para obtenção da molécula purificada e estudos de polimerização com o monômero obtido. O processo desenvolvido consistiu no aquecimento do caldo fermentado seguido pela etapa de centrifugação. A etapa de clarificação foi realizada utilizando carvão ativado em pó seguida pela precipitação a baixa temperatura e acidificação do lactato de cálcio para conversão em ácido lático. O processo foi efetivo para remoção de contaminantes que estavam presentes no caldo fermentado. A concentração final de AL em solução aquosa foi de 416 g/L com um rendimento de 51%. Os estudos de polimerização foram desenvolvidos utilizando a técnica de policondensação direta do AL, por meio de dois diferentes sistemas de aquecimento, convencional e micro-ondas. Um polímero com massa molar de 6330 g/mol e 61% de rendimento foi obtido a partir de um AL comercial e utilizando o AL obtido por fermentação resultou em um polímero com massa molar de 2370 g/mol. O processo de aquecimento por micro-ondas proporcionou um maior rendimento, 79% e 76% para o AL comercial e obtido por fermentação, respectivamente. Porém, foi obtida menor massa molar que o processo convencional, 2070 para o AL comercial e 1450 para o AL obtido por fermentação. As propriedades físico-químicas do poli(ácido lático) demonstraram aplicação em encapsulamento de compostos bioativos e engenharia de tecido. As perspectivas de sequência de estudos são a aplicação em encapsulamento de moléculas, modificações do polímeros e desenvolvimento de compósitos. PALAVRAS CHAVE: Poli(ácido lático), sub-produto do processamento da batata, caldo de cana, policondensação
Abstract: Poly (lactic acid) (PLA) is a polyester, which has a predominant role as biodegradable plastic, that is applied in packaging, textile, medical and pharmaceutical products. It can be obtained from lactic acid by direct polycondensation and by ring-opening polymerization (ROP) of lactide. Lactic acid (LA) is an organic acid that presents diverse applications mostly in food industry, as well as in pharmaceutical, chemical industries and polymers. The production of LA by fermentation offers the advantage of producing optically high pure LA. Nutritional requirements of bacteria increase the cost of LA production so alternatives substrates have been studied to bring an economical alternative for this process. The aim of this work was the production of LA by Lactobacillus pentosus in submerged fermentation using potato processing waste and sugarcane juice as substrate in order to obtain poly(lactic acid). The fermentation process was developed using potato processing waste and sugarcane juice because of their high carbon source concentration. Important volumes of both sub-products were generated, which is another reason for their re-use and valorization. Potato processing waste was submitted to hydrolysis in order to convert starch to glucose. LA production by fermentation was optimized using, statistical experimental design approach steps of optimization involved the screening of bacteria of the genus Lactobacillus and definition of medium composition kinetics studies in Erlenmeyer flask and stirred tank reactor were also carried out. LA production reached 150 g/l using potato processing waste, it was and 225 g/l with sugar cane juice after 96 hours of fermentation. The use of baker's yeast as a source of nitrogen and nonsterile conditions demonstrated good alternatives for an industrial production process of LA. The separation and recovery process of LA from fermented broth was developed to obtain a purified molecule for further polymerization studies. The developed process consisted in heating the fermented broth, then a centrifugation step was conducted for removal of the cells and suspended solids. A clarification step was included with powered activated carbon with further precipitation at low temperature and acidification of calcium lactate to convert to LA. The process was effective for removal of contaminants that were present in the fermentation medium. Final concentration of LA in aqueous solution reached 416 g/l and a yield of 51%. Polymerization studies were then carried out using direct polycondensation of LA, that were carried out with two different heating systems, conventional and microwave heating. A polymer with 6330 g/mol of molecular weight and 61% of yield was obtained from commercial LA and using fermented LA resulted in 2370 g/mol. Microwave heating process provided a higher yield, 79% and 76% for commercial and fermented LA, respectively. Nevertheless, the molecular weight was lower than conventional process, 2070 for commercial LA and 1450 for fermented LA. Physicochemical properties of PLA demonstrated application in encapsulation of bioactive compounds and tissue engineering. Perspectives of sequence of the studies: application on encapsulation of molecules, modifications of polymer and development of composites. KEYWORDS: Poly(lactic acid); potato processing waste; sugarcane juice; polycondensation
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Humphreys, S. "Glycopeptide resistance in lactic acid bacteria." Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604779.
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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.
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Nuraida, Lilis. "Metabolic studies on lactic acid bacteria." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314794.
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Gostick, Dominic Owen. "Transcription regulators of lactic acid bacteria." Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286585.
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De, Silva L. L. S. S. K. "Lactic acid fermentation of shrimp waste." Thesis, Loughborough University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314517.
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Lei, Xia. "Blends of High Molecular Weight Poly(lactic acid) (PLA) with Copolymers of 2-bromo-3-hydroxypropionic Acid And Lactic Acid (PLB)." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1367402061.
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Nguyen, Van Chuc. "Catalytic production and esterification of aqueous solution of lactic acid." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1136.
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Cette thèse porte sur la production d'acide lactique par conversion de la biomasse lignocellulosique catalysée par des acides de Lewis solides dans l'eau puis l'estérification d'acide lactique aqueux avec de l'éthanol. La conversion de la cellulose est étudiée en autoclave, en utilisant comme catalyseurs, de la zircone et de l'alumine contenant du W ou Sn (ZrW, AlSn) et différents hydroxydes métalliques. L'étude de la conversion de la cellulose en acide lactique en présence de ZrW non calcinée, ZrW calcinée, Zr(OH)4 et ZrO2, montre que la phase active du catalyseur est constituée de Zr4+, les centres acides de Lewis et de groupes hydroxyles. Les performances catalytiques des catalyseurs AlSn, préparés à partir de chlorure d'étain comme précurseur, dépendent fortement de la présence résiduelle de chlorure, ce qui favorise la formation d'acide lévulinique. Les hydroxydes de certains métaux de transition se sont révélés être des catalyseurs solides efficaces pour la conversion de la cellulose en acide lactique. Il a été observé que le rendement en acide lactique dépend de la concentration et de la basicité des groupes OH superficiels des hydroxydes de métaux de transition et de la présence de sites acides de Lewis. L'estérification de l'acide lactique, à différentes concentrations en l'eau, a été étudiée en présence d'Amberlyst 15, de charbon sulfoné et d'oxyde de graphène pour étudier l'activité et la tolérance à l'eau de catalyseurs solides acides à base de carbone. Il est montré, par calorimétrie d'adsorption d'ammoniac, que l'oxyde de graphène présente des sites superacides et qu'il conduit à la plus grande activité et tolérance à l'eau. L'augmentation de la teneur en eau montre un fort effet inhibiteur sur l'activité du charbon sulfoné alors que d'Amberlyst 15 et l'oxyde de graphène sont plus tolérants. Les catalyseurs ne sont pas stables dans des conditions d'estérification, en présence d'eauThis thesis reports the synthesis of lactic acid from lignocellulosic biomass catalyzed by solid Lewis acid catalysts in water and then esterification of aqueous lactic acid solutions with ethanol. The cellulose conversion was tested in autoclave, in hot water, using zirconia and alumina containing W or Sn (ZrW, AlSn) and different solid metal hydroxides. The conversion of cellulose to lactic acid using uncalcined ZrW, calcined ZrW, Zr(OH)4 and ZrO2 shows that the active surface of the catalyst consists of Zr4+ Lewis centers and OH groups. The catalytic performances of AlSn catalysts, prepared from Sn chloride as precursors, strongly depend on the residual amount of chloride which favors the formation of levulinic acid. Some hydroxides of transition metals were disclosed as efficient solid catalysts for the conversion of cellulose to lactic acid. The yield of lactic acid was observed to depend on the concentration and the basicity of the superficial OH groups and on the presence of Lewis acid sites. The esterification of lactic acid, at different concentrations in water, was studied using Amberlyst 15, sulfonated carbon and graphene oxide to evaluate the activities and water tolerance of carbon based solid catalysts. Graphene oxide, shown by calorimetry of NH3 adsorption to exhibit super-acid sites, leads the highest activity and water tolerance. Increasing amounts of water has a strong inhibiting effect on the activity of sulfonated carbon and less influence on activity of Amberlyst 15 and graphene oxide. However, all catalysts were not stable in esterification conditions, in presence of water
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Ahmad, Khalid Akeel. "Cloning Lux genes into lactic acid bacteria." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280525.
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Ha, Thi Quyen, and Thi Minh Tu Hoa. "Selection of lactic acid bacteria producing bacteriocin." Technische Universität Dresden, 2016. https://tud.qucosa.de/id/qucosa%3A32636.
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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.
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Shyamroy, S. "Synthesis of biodegradable poly (lactic acid) polymers." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2003. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2861.
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Okuklu, Burcu Güneş Hatice. "Investigation of chromosomal and plasmid dna profiles of lactococcus lactics ssp. lactis/." [s.l.]: [s.n.], 2005. http://library.iyte.edu.tr/tezler/master/biyoloji/T000396.pdf.
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Thesis (Master)--İzmir Institute of Technology, İzmir, 2005Keywords: Lactococcus lactis ssp. lactis, chromosome profiling, pulsed field gel electrophoresis, plasmid profiling, plasmid stability. Includes bibliographical references (leaves 58-63)
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Planes, Jordi. "Lactic acid production extractive fermentation in acqueous two-phase systems /." Lund : Dept. of Applied Microbiology, Lund University, 1998. http://catalog.hathitrust.org/api/volumes/oclc/40264909.html.
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Yalcin, Ozgen. "Production Of Lactic Acid Esters By Reactive Distillation." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613618/index.pdf.
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The esterification of lactic acid with ethanol over Lewatit S 100, strong cation ion exchange resin catalyst, was studied in counter current vapor-liquid contactor type differential reactor by feeding ethanol and lactic acid solution as vapor and liquid phases, respectively. The ethanol vapor phase was diluted by dry air and the water removal was achieved by the mass transfer of water from liquid to vapor phase. Effect of ethanol to lactic acid feed molar ratio and vapor flow rate on fractional conversion and water removal efficiency were tested at 40-70°C of column temperature range. It was observed that Lewatit S 100 was adequate catalyst for esterification of lactic acid with ethanol. Increase in ethanol to lactic acid feed molar ratio enhanced both lactic acid conversion and water removal by upper product stream. However, lactic acid conversion was suppressed by the increase of inlet vapor flow rate because of the decrease in ethanol concentration in gas phase which affected both esterification reaction rate and mass transfer rate. The reaction temperature is the other important parameter that affects the mass transfer of ethanol from vapor to liquid phase. Although reaction rate and equilibrium conversion values were promoted by temperature, the lower solubility of ethanol in liquid phase limited the fractional conversion while promoted the water mass transfer from liquid to vapor phase. The optimized vapor phase velocity and temperature can yield higher conversions than the equilibrium conversion at the same temperature and initial composition. Therefore, low pressure organic acids such as lactic acid can be successfully esterified by using counter current V-L contactor type reactors and by using integrated reaction and separation units.
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Jones, Rachael Ann. "Investigation of exopolysaccharide production by lactic acid bacteria." Thesis, Robert Gordon University, 2008. http://hdl.handle.net/10059/1252.
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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.
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Fernandez-Morales, H. "Studies of gene expression in lactic acid bacteria." Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403179.
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Newbold, Charles James. "Microbial metabolism of lactic acid in the rumen." Thesis, University of Glasgow, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235529.
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Archer, Martine. "Potential for lactic acid bacteria as food biopreservatives." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239170.
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Al-Dabbagh, Wail. "Studies on the preservation of lactic acid bacteria." Thesis, University of Strathclyde, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280404.
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Li, Yonghui. "Biodegradable poly(lactic acid) nanocomposites: synthesis and characterization." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/8543.
Full textAbstract:
Doctor of PhilosophyDepartment of Grain Science and Industry
X. Susan Sun
Biobased polymers derived from renewable resources are increasingly important due to acute concerns about the environmental issues and limited petroleum resources. Poly(lactic acid) (PLA) is such a polymer that has shown great potential to produce biodegradable plastics. However, low glass transition temperature (Tg), low thermal stability, slow biodegradation rate, and high cost limit its broad applications. This dissertation seeks to overcome these limitations by reinforcing PLA with inorganic nanoparticles and low-cost agricultural residues. We first synthesized PLA nanocomposites by in situ melt polycondensation of L-lactic acid and surface-hydroxylized nanoparticles (MgO nanocrystals and TiO2 nanowires) and investigated the structure-property relationships. PLA grafted nanoparticles (PLA-g-MgO, PLA-g-TiO2) were isolated from the bulk nanocomposites via repeated dispersion/centrifugation processes. The covalent grafting of PLA chains onto nanoparticle surface was confirmed by Fourier transform infrared spectroscopy and thermalgravimetric analysis (TGA). Transmission electron microscopy and differential scanning calorimetry (DSC) results also sustained the presence of the third phase. Morphological images showed uniform dispersion of nanoparticles in the PLA matrix and demonstrated a strong interfacial interaction between them. Calculation based on TGA revealed that more than 42.5% PLA was successfully grafted into PLA-g-MgO and more than 30% was grafted into PLA-g-TiO2. Those grafted PLA chains exhibited significantly increased thermal stability. The Tg of PLA-g-TiO2 was improved by 7 °C compared with that of pure PLA. We also reinforced PLA with low-value agricultural residues, including wood flour (WF), soy flour (SF), and distillers dried grains with solubles (DDGS) by thermal blending. Tensile measurements and morphological images indicated that methylene diphenyl diisocyanate (MDI) was an effective coupling agent for PLA/WF and PLA/DDGS systems. MDI compatibilized PLA/WF and PLA/DDGS composites showed comparable tensile strength and elongation at break as pure PLA, with obviously increased Young’s modulus. Increased crystallinity was observed for PLA composites with SF and DDGS. Such PLA composites have similar or superior properties compared with pure PLA, especially at a lower cost and higher biodegradation rate than pure PLA. The results from this study are promising. These novel PLA thermoplastic composites with enhanced properties have potential for many applications, such as packaging materials, textiles, appliance components, autoparts, and medical implants.
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Corre, Yves-Marie. "Poly (lactic acid) foaming assisted by supercritical CO2." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0106/these.pdf.
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The poly (lactic acid) (PLA), through its organic origin and its biodegradation properties, can be a good alternative to petroleum-based polymers. To this end, the foaming of PLA by supercritical CO2 was evaluated in this study as an alternative to expanded polystyrene (EPS) for the production of food packaging. Because low rheological properties of this type of polyester, a first chain extension step was necessary to ensure a good foaming ability of PLA. Following a full characterization in physicochemical, rheological and thermal domain, a batch foaming assisted with supercritical CO2 was achieved. The influence of the foaming parameters, the extent of chain modificaton as well as the contribution of crystallization on cell morphology was evaluated. Based on these parameters, structures ranging from micro to macro-cellular-cell were obtainedLe polylactide (PLA), par son origine bio sourcée et ses propriétés de biodégradation, peut être une bonne alternative aux polymères issus du pétrole. Dans cet objectif, le moussage du PLA par CO2 supercritique a été évalué dans cette étude comme substitution au polystyrène expansé (PSE) pour la production d'emballages alimentaires. Du fait des propriétés rhéologiques faibles de ce type de polyester, une première étape d'extension de chaînes a été nécessaire afin de garantir des bonnes aptitudes au moussage du PLA. Suite a une caractérisation complète dans le domaine physico-chimique, rhéologique et thermique, une étude de moussage en mode batch sous CO2 supercritique a été réalisée. Les paramètres de moussage, le taux de modification du matériau ainsi que de l'apport de la cristallisation sur la morphologie cellulaire ont été évalués. En fonction de ces différents paramètres, des structures allant du micro-cellulaire au macro-cellulaire ont été obtenues
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Gonçalves, Carla Maria Batista. "Barrier properties of poly(lactic acid) based films." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14296.
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Doutoramento em Engenharia QuímicaIn recent years, the search for a environmentally friendly products has increased. One of the major challenges has been the demand for biodegradable materials that can replace plastic. If a few decades ago, plastic replaced, for example, the ivory in billiard balls, and in other products, saving the lives of thousands elephants, nowadays a replacement for that plastic is being searched, to prevent the change of the environmental conditions, essential to life in harmonly with the fauna and flora that the human specie has, in recent years, destroyed. Plastic is a petroleum derivate, whose price has been growing exponentially, mainly due to the fact of beind a cheap material and also to enable the production of products that are essential to modern life. Therefore, the petrochemical era is going to come to an end and a new environmentally sustainable era, based on biodegradable materials from renewable sources, will follow. The change to green routes only will be possible with the support of the major companies, and the implementation of drastic governmental law. Poly(lactic acid), PLA, is produced from the lactose present in the corn or sugarcane and has been intensively studied in recent years because if some limitants properties required its extrusion are overcome, it has the potential to replace the traditional polymers. PLA have high brittleness, low toughness and low tensile elongation. In this work, natural antioxidant (alpha-tocopherol) and synthetics antioxidants (BHT ant TBHQ) were added to the PLA with the aim not only to improve their flexibility, but also to create an active packaging to extend the shelf life of the foods and improve the organoleptic properties by preventing food losses. The impact of the addition of antioxidants into the PLA films, in its mechanical, thermal and barrier properties were studied by FTIR, DSC, SEM, AFM, DMA, TGA, QCM and time-lag techniques.
Nos últimos anos temos assistido à procura de produtos amigos do ambiente. Um dos maiores desafios tem sido a procura de materiais biodegradáveis que possam substituir materiais vulgarmente designados por “plástico”. Se há dezenas de anos o plástico veio, por exemplo, substituir o marfim nas bolas de bilhar, salvando vidas de milhares de elefantes, hoje, procuramos um substituto para esse plástico, de forma a preservar as condições ambientais que nos permitem viver harmoniosamente com a restante fauna e flora, e que a espécie humana tem, nos últimos anos, vindo a destruir. O plástico é um derivado do petróleo, cujo preço tem vindo a crescer exponencialmente, devido ao facto de ser barato e possuir propriedades que permitem desenhar produtos essenciais à vida quotidiana. Por isso, precisamos de sair da era petroquímica e entrar numa nova era ambientalmente sustentável, baseada em materiais biodegradáveis provenientes de fontes renováveis. Esta mudança para rotas “verdes”, só será possível com o apoio de grandes empresas, e medidas governamentais drásticas. O poliácido láctico, PLA, produzido a partir da lactose presente no amido ou no açúcar, tem sido intensivamente estudado nos últimos anos e possui potencial para substituir os tradicionais polímeros derivados do petróleo, se forem melhoradas algumas propriedades necessárias ao processamento por extrusão. O PLA, é muito frágil, pouco resistente e pouco flexível. Neste trabalho foram adicionados antioxidantes naturais (alfa-tocoferol) e sintéticos (BHT e TBHQ) ao PLA com o objetivo não só de melhorar as suas propriedades mecânicas, mas também de criar uma embalagem ativa que prolongue o prazo de validade dos alimentos e melhore as suas propriedades organoléticas prevenindo alterações ou perda de sabor. O impacto da adição destes antioxidantes nas propriedades originais do PLA a nível mecânico, térmico e de barreira foi estudado pela utilização das técnicas de FTIR, DSC, SEM, AFM, DMA, TGA, QCM e time-lag.
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Altıok, Duygu Tokatlı Figen. "Kinetic modelling of lactic acid production from whey/." [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/gidamuh/T000471.pdf.
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Rasal, Rahul M. "Surface and bulk modification of poly(lactic acid)." Connect to this title online, 2009. http://etd.lib.clemson.edu/documents/1246558434/.
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Scheppler, Lorenz. "The use of lactic acid bacteria for vaccination /." [S.l.] : [s.n.], 2004. http://www.zb.unibe.ch/download/eldiss/04scheppler_l.pdf.
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Sinclair, Fern. "Modification of poly(lactic acid) via olefin cross-metathesis." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28896.
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Poly(lactic acid), PLA, is a viable replacement to petroleum derived polymers due to its renewable feedstock, biodegradability and bioassimilability, yet improvements in its physical, thermal and mechanical properties are required before it can fully enter all commodity markets. This thesis investigates olefin cross-metathesis (CM) as a synthetic strategy to modify the properties of PLA. The use of novel lanthanide and actinide catalysts on the microstructure control of PLA are also explored. The Tebbe reagent was used in a new synthetic strategy to produce a novel olefin derivative of lactide (MML). Olefin CM of MML with hex-1-ene was successful but polymerisation pre- and post-CM was unsuccessful due to monomer instability. CM of another olefin derivative of lactide, 3-methylenated lactide (3-ML) was successful with aliphatic alkenes; hex-1-ene to dodec-1-ene. To overcome competing alcoholysis of the functionalised monomers, which prevented polymerisation, hydrogenation was used to remove the olefin entity followed by successful ring-opening polymerisation (ROP) to produce polymers of low glass-transition temperatures (Tg). Post-polymerisation CM on an olefin containing polymer P(β-heptenolactone) P(β-HL), with methyl acrylate and an epoxide, generated functionalised homopolymers with increased Tg’s. Co-polymerisation of lactide with β-HL generated novel gradient-copolymers. Olefin CM with 15 different cross-partners produced functionalised copolymers with different thermal properties. Based on this route a new methodology was created to introduce two unique functionalities into the polymer backbone by manipulation of the olefin reactivities. Finally, in a collaborative project, uranium and cerium catalysts, Me3SiOU(OArP)3 and Me3SiOCe(OArP)3 - designed out-with the group- were tested and compared as ROP catalysts for lactide. Both catalysts were active in living polymerisations of L-lactide and under immortal conditions the activity and rates of the catalysts were switched, accounted for by a change in the coordination sphere due to ligand displacement. ROP of rac-lactide using the uranium analogue produced heterotactic-biased PLA with a Pr = 0.79.
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Noga, David Edward. "Synthesis of functional lactide copolymers for use in biomedical applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/29646.
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Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Collard, David M.; Committee Member: García, Andrés J.; Committee Member: Tolbert, Laren; Committee Member: Wang, Yadong; Committee Member: Weck, Marcus. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Jalali, Amirjalal. "Quiescent and flow-induced crystallization of poly(lactic acid)." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/9892.
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Le poly(acide lactique), PLA, est un polymère biocompatible et biodégradable, qui peut être
produit à partir de ressources renouvelables. En conséquence, il a soulevé une attention toute
particulière en tant que remplacement éventuel des polymères à base de pétrole. C’est un
polyester aliphatique ayant des propriétés telles que module élevé, haute résistance,
biocompatibilité et est donc un matériau prometteur pour diverses applications telles que les
implants, l’encapsulation de médicaments et l'emballage. A cause de sa faible température de
transition vitreuse, le PLA a une faible résistance thermique et les applications sont donc
limitées à celles qui ne sont pas associées à des températures élevées. En outre, ce polymère
souffre d'un faible degré de cristallinité. L'augmentation du taux de cristallinité dans de
nombreuses techniques de mise en forme, telles que le moulage par injection, est nécessaire.
Il y a plusieurs façons d'augmenter le niveau de cristallinité du PLA. Ces procédés
comprennent l'utilisation d'agents nucléants, de plastifiants, ou de combinaisons d'agents
plastifiants et de nucléation. La cristallisation du PLA à l'état fondu se présente sous deux
formes cristallines légèrement différentes connues sous les noms α et α'. Cette étude compare
la capacité d'auto-nucléation de ces deux formes cristallines par auto-nucléation. Ceci est
réalisé en comparant les températures de cristallisation lors du refroidissement des
échantillons préalablement cristallisés à diverses températures, puis de nouveau chauffé à une
température dans la plage de fusion partielle du PLA. Dans la deuxième étape, l'effet des
paramètres cinétiques et le poids moléculaire du PLA sur l'efficacité de nucléation des PLA
phases cristallines a été étudié. Cette partie de l’étude ouvre une nouvelle voie pour
comprendre le rôle des modifications cristallines du PLA qui mènent aux conditions optimales
pour la cristallisation du PLA. La mise en forme des polymères implique des contraintes de
cisaillement et d’élongation, ce qui implique une cristallisation induite par l’écoulement et la
solidification qui s’en suit. Les propriétés mécaniques des produits finals dépendent du degré
de cristallisation et de la nature des cristaux formés. Par conséquent, l'optimisation du procédé
nécessite une bonne compréhension de la façon dont l’écoulement influence la cristallisation.
Le type d'écoulement peut jouer un rôle important sur la cristallisation. Par exemple,
l'écoulement élongationnel provoque l’orientation et l’étirement des molécules dans le sens de
l'extension, comme dans le cas de la mise en forme de fibres et le soufflage de film, en aidant
le processus de cristallisation induite par l'écoulement. Une littérature abondante existe sur la
ii
cristallisation des thermoplastiques classiques induite par l'écoulement. Cela dit, moins
d'attention a été accordée à l'effet de l'écoulement de cisaillement et d'allongement sur la
cristallisation du PLA. Comme étudié dans la dernière partie de ce document, l'effet du poids
moléculaire sur la cristallisation induite par cisaillement du PLA est rapporté. Pour cela, trois
différents PLA à faible, moyen et haut poids moléculaire ont été préparés par réaction
d'hydrolyse. Ensuite, en utilisant un rhéomètre oscillatoire, l’effet du cisaillement sur la
cinétique de cristallisation du PLA a été examiné.Abstract : Poly(lactic acid), PLA, is a biocompatible and biodegradable polymer that can be produced from renewable resources. As a result, it has raised particular attention as a potential replacement for petroleum-based polymers. It is an aliphatic polyester with properties such as high modulus, high strength, and biocompatibility and is thus a promising material for various applications such as implants, drug encapsulation, and packaging. In the wake of low glass transition temperature, PLA has a low heat resistance and its application is limited to those not associated with high temperatures. In addition, this polymer suffers from a low degree of crystalinity. Increasing the crystallization rate in many processing operations, such as injection molding, is required. So far, many routes have been found to improve the crystallinity of PLA. These methods include using nucleating agents, plasticizers, and combination of nucleating agents and plasticizers together. PLA crystallization in the melt state results in two slightly different crystalline forms known as α and α’forms. This thesis compares the self-nucleation ability of these two crystal forms by self-nucleation. This is achieved by comparing crystallization temperatures upon cooling for samples previously crystallized at various temperatures and then re-heated to a temperature in the partial melting range for PLA. In the second step, we study the effect of molecular weight of PLA on the nucleation efficiency of PLA crystalline phases. This part of the investigation opens a new pathway to understand the role of PLA crystalline phases on the optimal condition for its crystallization kinetics. Polymer processing operations involve mixed shear and elongational flows and cause polymer molecules to experience flow-induced crystallization during flow and subsequent solidification. The mechanical properties of the final products are significantly dependent upon the degree of crystallization and types of formed crystals. Therefore, optimization of any polymer process requires a good understanding of how flow influences crystallization. The type of flow can play a significant role in affecting crystallization. For example, elongational flow causes molecules to orient and stretch in the direction of extension, as in the case of fiber spinning and film blowing, helping the process of flow-induced crystallization. An extensive body of literature exists on flow-induced crystallization of conventional thermoplastics. Having said that, less attention has been paid to the effect of shear and elongational flow on the PLA crystallization kinetics. As investigated in the final part of this thesis, the effect of iv molecular weight on the shear-induced crystallization of PLA is reported. For this, low, medium and high molecular-weight PLAs were prepared from a high molecular weight one by a hydrolysis reaction. Next, by means of a simple rotational rheometry, effect of the shear flow was examined on the crystallization kinetics of these three PLAs.
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Takeuchi, Michiki. "Biochemical and applied studies on unsaturated fatty acid metabolisms in lactic acid bacteria." Kyoto University, 2015. http://hdl.handle.net/2433/199370.
Full textAbstract:
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
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Craig, Kelsey L. Craig. "A Novel Lactic Acid Bacteria (LAB)-based Vaccine Candidate for Human Norovirus." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524170939202923.
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Lenti, Mattia. "Triethyl citrate-based oligomeric plasticizers for poly(lactic acid)." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15760/.
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Poly(lactic acid) (PLA) is a bio-based, biocompatible, biodegradable polymer that can be produced from renewable resources including starch from corn and potatoes, sugar from beets and sugar cane. Poly(lactic acid) and its copolymers have attracted significant attention in environmental, biomedical, and pharmaceutical applications and as alternatives to petroleum-based polymers. Due to the relatively high glass transition temperature (55°C) and low crystallization rate which respectively result in a brittle behaviour and low production efficiency, the use of a plasticizer is critical to meet technological requirements. Low molecular weight plasticizers show migration issues over time while blending PLA with lower Tg polymers may result in phase separation. Our approach to tackle those issues was to synthetize a novel type of plasticizer containing an oligomeric PLA chain to which a triethyl citrate functionality is grafted as end-chain group. This system guarantees maximum compatibility with the polymeric matrix while still providing an improvement in the material properties. Triethyl citrate (TEC) is a bio-based and biocompatible compound so the “green” properties of PLA are retained. Synthesis and characterization of the plasticizer are described in this research project. The thermal properties of the plasticizers have been investigated using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Upon addition of the plasticizer PLA shows a decrease in the glass transition temperature and an increase in the crystallinity which results in a higher storage modulus.
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Bahcecioglu, Gokhan. "Poly(l-lactic Acid) (plla)-based Meniscus Tissue Engineering." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613968/index.pdf.
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Meniscus is a fibrocartilaginous tissue which plays an important role in joint stability, lubrication, and load bearing and transmission. Meniscal tears are commonly encountered in sports activities, or caused by degeneration of the cartilage with ageing. They lead to pain, loss of work, disturbed biomechanics of the knee and inability to walk or even move the legs. As the meniscal tissue is avascular in the inner portion, injury to this part does not heal by itself, and therefore treatments are needed. In some cases when complex tears occur, the tissue cannot be successfully treated with the conventional methods.
Tissue engineering appears to be a promising alternative to treat such complex tears. It includes the application of cells on scaffolds (or cell carriers), and provision of bioactive agents to the site of injury in order to regenerate the damaged tissue. The cells and the bioactive agents are involved in the synthesis of the new tissue, while the scaffold acts as a support to guide the cells until the new tissue is formed, and it is slowly absorbed by the body leaving the new tissue behind. Thus, a natural tissue is generated at the end. Few studies have been reported on the tissue engineering of meniscus, but neither of them was able to completely mimic the meniscus structure, nor could they succeed in constructing scaffolds with sufficiently high tensile properties.
In the current in vitro study, a novel 3D construct was proposed, in which the natural tissue is perfectly mimicked. The 3D construct consisted of aligned collagen fibers embedded within a foam network which stabilizes the structure. The foam was prepared by freezing a polymer solution with a certain concentration, and lyophilizing it. Aligned fibers were aimed to improve the tensile properties. The construct was impregnated in alginate gel, which was then crosslinked, to improve the compressive properties.
The foam was prepared from (poly(L-lactic acid)/poly(lactic-co-glycolic acid) (PLLA/PLGA) solutions of various concentrations (2%, 2.5%, 3%, and 4% w/v) and at different freezing temperatures (-20oC or -80oC) to select the best preparation condition. After analysis of the microstructure and mechanical properties, foams prepared from 3% polymer solution frozen at -20oC were found to be the most appropriate for use as scaffold for the 3D construct, since they had large pores, high and interconnected porosity, as well as high mechanical strength.
The 3D constructs were seeded with human meniscus cells and incubated for 21 days. Cell behavior on the constructs was examined. Cell attachment and proliferation was found to be better with the constructs not coated with alginate. However, the constructs coated with alginate demonstrated higher compressive strength. It was also found that incorporation of collagen fibers significantly improved the tensile properties.
All the constructs were shown to lead to the production of extracellular components specific for fibrocartilages, and thus it was concluded that they were promising for use in meniscal replacement.
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Liao, Wen-Chyn, and 廖文勤. "Preparation of Lactic-Fermented Ulva lactuca Drink by Mixed Lactic acid Bacteria." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/39342972108862731632.
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碩士國立臺灣海洋大學
食品科學系
99
The aim of this research are to investigate first the hydrolytic conditions for cellulase to hydrolyze the Ulva lactuca, to ferment the Ulva hydrolysate using lactic acid bacteria (LAB), and finally to investigate the anti-oxidant activity of LAB-fermented Ulva product. The optimal temperature and pH value for cellulose with 5 units/mL to hydrolyze 2% Ulva suspention are 45℃ and pH 6.0, respectively. Five strains including Lactococcus lactis subsp. Lactis BCRC 12315 ,12322, Lactobacillus bulgaricus BCRC 10696, Lb. Plantarum BCRC 10069 and Bifidobacterium parvulorum BCRC 14601 were used as the tested LAB. Except BCRC 12322, the bacteria counts for the rest 4 LAB strains were above 108 CFU/mL after inoculation in Ulva hydrolysate at 37℃ for 8hr. The ferrous-ion chelating activities of Ulva hot extract and Ulva hydrolysate were 81.54% - 97.25%, which were significantly higher than those LAB – formented product (31.41% - 43.29%) . DPPH scavenging activities of Ulva hydrolysate and LAB – formented Ulva product were very low (3.54% ~ 6.05%). Trolox equivalent antioxidant capacity (TEAC) of raw materials and lactics-fermented Ulva hydrolysate were 290 - 1080μM, Inhibition of ascorbate auto-oxidation the fermented product were 75.06 - 184.33μg (Vit. C Equivalent / mL), total phenolic contcent of the fermented product were 75.50 - 126.89μg/mL. Adding with 3% soybean milk or black bean milk as supplement promoted the growth of LAB obviously and the effects were better than adding 3% red bean milk. In addition, supplanting with 3% black bean milk, the ferrous-ion chelating activity, DPPH scavenging activity, TEAC, inhibition of ascorbate auto - oxidation and total phenolic content were all higher than Ulva hydrolusate supplemented with red and soy beans . All two stains combination contented BCRC 14601 fermented products were above 108 CFU / mL, pH lower than 4.5 after 2 to 4 hours incubation. The fermented products of BCRC 14601 and BCRC 10696 had best flavor, reduction activities, TEAC and all estimated activities were greater than the unfermented raw materials and Ulva hydrolysate significantly. The total phenolic content was 484.02 μg / mL, ferrous-ion chelating activity, DPPH scavenging activity, TEAC and Inhibition of ascorbate auto-oxidation of this combination were 52.57% , 34.92%, 540 μM, and 722.86 μg (Vit. C Equivalent / mL), respectively. This combination had best flavor scores when supplemented with 3% black bean milk , the scores were falvor 6.78 ± 0.89, taste 7.02 ± 0.81, and overall acceptability 7.64 ± 1.05 respectively.
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Xavier, Ana Marta Moniz. "Study of lactic acid polycondensation and lactide production." Master's thesis, 2010. http://hdl.handle.net/10216/62094.
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Xavier, Ana Marta Moniz. "Study of lactic acid polycondensation and lactide production." Dissertação, 2010. http://hdl.handle.net/10216/62094.
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Yi-KwanChen and 陳伊寬. "Adsorption and Reactions of Lactic Acid and Poly(lactic acid) on Powdered TiO2." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24267332960729017883.
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碩士國立成功大學
化學系碩博士班
98
Fourier-transform infrared spectroscopy has been employed to investigate the adsorption and reactions of lactic acid and poly(lactic acid) on powdered TiO2(35 ℃). Lactic acid can dissociate when exposed to the surface of TiO2. The carboxyl group deprotonates to form a carboxylate or the hydroxyl group breaks the O-H bond to form an alkoxy group on TiO2. As the temperature is raised higher than 250 ℃ in the absence of O2, it is found that propionate is formed, with minor acetate and gaseous CO2. In the presence of O2, acetate and CO2 are the only products detected after the lactic acid decomposition. Dehydration of lactic acid on TiO2 to form acrylate dose not occur. In the case of absorption of poly(lactic acid) on TiO2, the polyester chains are broken, forming carboxylate species, when exposed to the surface. Poly(lactic acid) has the same thermal decomposition products as those of lactic acid on TiO2. Poly(lactic acid) on TiO2 is subjected to photooxidation. Approximately 55% of poly(lactic acid) decompose to form acetate and CO2 under UV irradiation for four hours in the presence of O2. Possible decomposition mechanisms for lactic acid and poly(lactic acid) on TiO2 are proposed.
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Chien, Chia Huang, and 簡嘉皇. "Conjugated Linoleic Acids Capacity of Lactic Acid Bacteria." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/2ag226.
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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.
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Chang, Shiao-Ming, and 張效銘. "Screen of Probiotic Lactic Acid Bacteria and Constructing Shuttle Vector of Lactic Acid Bacteria." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/72669138520421636077.
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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.
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Sudha, K. "Microbial production of Lactic Acid." Thesis, 1998. http://hdl.handle.net/2009/1628.
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Hsin-PingChen and 陳欣平. "Spherulitic Morphology and Lamellar Assembly in Nonequimolar Mixtures of Poly(L-lactic acid) with Poly(D-lactic acid) and Solution-Cast Poly(L-lactic acid) Films." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/ajvqb8.
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碩士國立成功大學
化學工程學系
105
Investigations on the morphology resulted from melt-crystallization of nonequimolar blends of PLLA with PDLA with regard to the prior melting temperature and crystallization temperature were conducted. When crystallized after melting at 190 oC, the PLLA/PDLA (95/5) blend exhibits large radiating-stripe spherulites surrounded by tiny spherical crystals. When crystallized after melting at 240 oC, the radiating-stripe spherulites appear with negative-type spherulites. Melting observation show that radiating-stripe spherulites belong to PLLA α-crystals, while negative-type spherulites belong to sc-PLA crystals. From the top surfaces of radiating-stripe spherulites, the lamellae are arranged at an angle of 60o with radial direction on the main stalk, while lamellae on the region between main stalks are arranged perpendicular to the main branch. Because of the difference in lamellar assembly, the blend shows different birefringence in the same quadrant, resulting in special morphology. For neat PLLA crystallized by solvent evaporation, PLLA exhibits ring-banded morphology at 26~30 oC with tetrahydrofuran as solvent. The top surface of ring-banded spherulites shows lamellae arranged in dendritic shape. Lamellae inside spherulites arrange in radial direction, and show layer structure from lateral view.
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Kao, Te-Yu, and 高德育. "Study on the Production of Lactic Acid from Algal Polysaccharide Hydrolysates via Lactic Acid Bacteria Fermentation." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/79570892658077330424.
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碩士國立臺灣海洋大學
食品科學系
102
The aim of this study is to produce lactic acid from three kinds of algal polysaccharide hydrolysates (Gracilaria sp., Sargassum siliquosum, and Ulva lactuca), which sequentially hydrolysis by hot acid, commercial enzymes, and crude enzymes from Pseudomonas vesicularis MA103 (MA103) and Aeromonas salmonicida MAEF108 (MAEF108) and fermented by lactic acid bacteria (LAB). Reducing sugar content per kWh electricity usage of 10% (w/v) Gracilaria sp., S. siliquosum, and U. lactuca powder hydrolyzed by 0.4 N HCl at 121oC for 30 min were 19.76, 11.07, and 15.99 mg/mL, respectively. MA103 incubated in artificial sea water medium added with hot water extracted Gracilaria sp. polysaccharide and HCl-extracted Gracilaria sp. polysaccharide (AM-Gra-AP) enriched with defatted soybean flour for 2 d, amylase activity was 6.76 U. While MAEF108 incubated in AM-Gra-AP that enriched with yeast extract for 3 d, agarase activity was 2.76 U. MA 103 and MAEF108 incubated in artificial sea water medium added with hot water extracted S. siliquosum polysaccharide (AM-Sar-P) that enriched with defatted soybean flour for 2 d, alginate lyase activity were 0.61 and 0.37 U, respectively. In artificial sea water medium added with hot water extracted U. lactuca polysaccharide and HCl-extracted U. lactuca polysaccharide (AM-Ulv-AP) that enriched with defatted soybean flour for 2 day, MA103 showed 5.30 U amylase activity and MAEF108 showed 0.26 U agarase activity. LAB selection showed that strains BCRC 10695, 12327, and isolate KP5 fermented in Gracilaria sp. polysaccharide hydrolysate resulted in lactic acid concentration of 6.96, 6.31, and 4.54 g/L, respectively. Strains BCRC 10695, 12327, and 14068 fermented in S. siliquosum polysaccharide hydrolysate resulted in lactic acid concentration of 5.38, 5.54, and 5.17 g/L, respectively. While strains BCRC 10695, 12327, and 14068 fermented in U. lactuca polysaccharide hydrolysate resulted in lactic acid concentration of 7.49, 8.37, and 7.96, respectively. Gracilaria sp. polysaccharide hydrolysate prepared by procedure A, 10% (w/v) seaweed power hydrolyzed by 0.4N HCl at 121oC for 30 min, 7,600 U cellulase, crude enzymes from MA 103 and MAEF 108 incubated in MMB-Gra and fermented by combination of 3% (v/v) Lb. acidophilus BCRC 10695 and 3% (v/v) Lb. plantarum BCRC 12327 with 0.5% (w/v) yeast extract as nitrogen sources resulted in 19.32 g/100 g lactic acid yield. Procedure B, conditions were the same as procedure A, except MMB-GraMA103 and MMB-GraMAEF108 were replaced by AM-Gra-APMA103 and AM-Gra-APMAEF108. In this hydrolysate, fermented by combination of 3% (v/v) Lb. acidophilus BCRC 10695 and 3% (v/v) Lb. plantarum BCRC 12327 with 0.5% (w/v) yeast extract as nitrogen sources resulted in 20.58 g/100 g lactic acid yield. Procedure C, with 5% (w/v) biomass loading extracted by 0.4N HCl at 121oC for 20 min and higher level of commercial enzyme compare to procedure A and used MMB as crude enzymes inducing medium, fermented by combination of 3% (v/v) Lb. acidophilus BCRC 10695 and 3% (v/v) Lb. plantarum BCRC 12327 with 0.5% (w/v) yeast extract as nitrogen sources resulted in 49.10 g/100 g lactic acid yield. Procedure A, B, and C of S. siliquosum polysaccharide hydrolysate were added 0.5% (w/v) okara as nitrogen sources fermented by combination of 3% (v/v) Lb. acidophilus BCRC 10695 and 3% (v/v) Lb. plantarum BCRC 12327 at 30oC, the lactic acid yield were 14.51, 14.58, 59.16 g per 100 g dried S. siliquosum, respectively. Procedure A, B, and C of U. lactuca polysaccharide hydrolysate were added with 5% (w/v) yeast extract as nitrogen sources fermented by LAB strain 6% (v/v) Lb. plantarum BCRC 12327 at 30oC, the lactic acid concentration were 12.19, 12.89, 50.22 g per 100 g dried U. lactuca, respectively.
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Wu, Wen-Shan, and 吳汶珊. "Batch fermentation of whey for lactic acid production using microtube array membrane-immobilized lactic acid bacteria." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/yw42rz.
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碩士國立臺灣海洋大學
食品科學系
107
Whey is the main by-product form the dairy manufacturing and its reuse has grab high attention frequently. Whey contents high amount of lactose, which is good for lactic acid fermentation and produce biodegradable plastic (polylactic acid, PLA). The use of a novel cell immobilization technology, poly-L-lactic acid microtube array membrane (PLLA-MTAM), in batch fermentation can effectively reduce the production costs and speed fermentation required time. This study aimed on the utilizing of reused lactose in whey and PLLA-MTAM immobilized cell, homofermentative lactic acid bacteria Lactobacillus acidophilus BCRC 10695, for the purpose of lactic acid production. Compare various concentrations of lactose in MRS broth and whey for lactic acid fermentation at 30oC for 72 hours, it was found that MRS broth contained 4% (w/v) lactose obtained the highest lactic acid concentration of 37.82 ± 1.30 g/L with lactose conversion ratio and lactic acid yield of 1.46 ± 0.11 g/g sugar. The whey contained 4% (w/v) lactose also showed the highest lactic acid production of 29.57 ± 0.18 g/L with lactose conversion ratio and lactic acid yield of 1.18 ± 0.01 g/g sugar. For tests of immobilization of microbial cells in fermentation process, the encapsulation efficiency of 109 CFU/mL of Lb. acidophilus BCRC 10695 immobilized on PLLA-MTAM was tested to be 70.6 ± 7.5%. The obtained lactic acid using this immobilization technology was 29.57 ± 0.18 g/L with lactose conversion rate and lactic acid yield of 1.18 ± 0.01 g/g sugar, started from 4% (w/v) lactose of whey.
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Lee, Kai-Chien, and 李楷謙. "Safety assessment of genetically modified lactic acid bacteria Lactococcus lactis NZ9000/pNZPNK." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/76749872059454398457.
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碩士國立臺灣大學
微生物與生化學研究所
97
The genetically modified microorganism (GMM) is derived from the techniques of modern biotechnology which is purposed to use in food and pharmaceutical industry. However, safety assessment for the potential risk of GMM must be considered. We introduced detection of antibiotic resistance genes, pepsin digestion assay and evaluation of intestinal microflora to assess the safety of GMM. The samples applied in this study were genetically modified lactic acid bacteria Lactococcus lactis NZ9000/pNZPNK and the host strain L. lactis NZ9000. Polymerase chain reaction (PCR) analysis of GM strain resulted in correct sequence of antibiotic resistance gene cat, indicating that antibiotic resistance gene remained unchanged after genetic engineering. By applying GM strain and host strain to pepsin digestion assay, the protein fractions of both soluble protein fractions and cell debris were degraded completely and rapidly. The produced nattokinase was undetectable after digestion with western blotting analysis. To assess the interaction between GM strain and intestinal microflora, Wistar rats received GM strain and host strain. Several important intestinal bacteria were counted. A significant increase in the count of Bifidobacterium in rat feces was observed after fed both GM and host strains for 4 weeks, but the count of Bifidobacterium had showed no significant change after fed GM and host strains for 6 weeks and the count of Clostridium perfringens in rat feces had no difference in all groups. These results suggest that Lactococcus lactis NZ9000/pNZPNK has low allergenicity and likely to be safe for human consumption.
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Yeh, Hsien-Che, and 葉憲哲. "Mutation and Cultivation of Actinobacillus Succinogenes and Lactic Acid-producing Strain for the Production of Succinic Acid and Lactic Acid." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/47560083349107232915.
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碩士國立中正大學
化學工程研究所
101
Lactic acid and succinic acid are the important intermediates for polymers, pharmaceuticals and chemicals. Also, they can be used as a food additive and dietary supplement. However, fermentation of lactic acid or succinic acid can lead to the production of acetic acid (acetate) as the byproduct, causing difficulty in subsequent purification and waste of carbon source. For example, succinic acid-producer A. succinogenes 130Z can accumulate acetate at approximately 0.114 g/g-glucose in shake flasks containing 30 g/L glucose. In this study, the wild-type A. succinogenes and lactic acid-producing strain were induced to mutation using NTG and mutants were screened on the sodium fluoroacetate-containing agar. A lactic acid-producing mutant strain was isolated and found able to produce acetate at only 0.067 g/g-glucose in the culture medium of 30 g/L glucose. In the fermenter, this lactic acid-producing mutant strain could produce approximately 50.62 ± 2.04 g/L lactic acid in the fermentation medium containing 85 g/L glucose initially, corresponding to the lactic acid yield of approximately 0.68 ± 0.07 g/g glucose. We also found that this mutant strain could grow significantly under CO2 aeration only in TSB medium and some specified fermentation media. Many tested culture conditions led to low proliferating rates and low lactic acid yields. The wild-type A. succinogenes was found able to produce acetate at 0.067 g/g-glucose in the culture medium of 85 g/L glucose. In the fermenter, this succinic acid-producing mutant strain could produce approximately 35.18 g/L succinic acid in the fermentation medium containing 85 g/L glucose initially, corresponding to the succinic acid yield of approximately 0.75 g/g glucose. Keywords: succinic acid, Actinobacillus succinogenes, mutation, acetate, sodium fluoroacetate, lactic acid
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Tsai, Pei-Fang, and 蔡佩芳. "Lactic acid bacteria behavior toward cholesterol." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/57361534836549259565.
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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.