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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Produção de enzimas fúngicas hidrolíticas para obtenção de amino-oligossacarídeos / Production of chitinolytic enzymes for the preparation of potentially bio-active amino-oligosaccharides

Honorato, Talita Lopes 12 February 2011 (has links)
Orientadores: Telma Teixeira Franco, Sueli Rodrigues / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T11:18:02Z (GMT). No. of bitstreams: 1 Honorato_TalitaLopes_D.pdf: 6860909 bytes, checksum: 13811fc8b567923905d4a11f6cfd1a1a (MD5) Previous issue date: 2011 / Resumo: Estudos sobre quitina e quitosana têm atraído interesse devido à sua possível conversão em oligossacarídeos, que são solúveis em água e apresentam atraentes atividades biológicas. Para este fim, métodos eficazes para a produção de amino-oligossacarídeos (AGO's) potencialmente bioativos são necessários. O trabalho objetivou estudar a viabilidade de Fermentação em Estado Sólido (FES) para a produção de um extrato enzimático adequado para a obtenção de AGO's. Inicialmente foi identificado um fungo adequado para a FES utilizando cascas de camarão como substrato, sendo uma cepa de Trichoderma polysporum selecionada. A otimização das condições da fermentação para obtenção de um extrato enzimático capaz de produzir AGO's com grau de polimerização em torno de 5, grau de polimerização considerado o mínimo adequado para bioatividades foi realizada e as enzimas produzidas por T. polysporum sob diferentes condições de fermentação (submersa e sólida) foram analisados por eletroforese, seguida pela atividade de coloração e por atividades enzimáticas utilizando substratos cromogênicos específicos. Atividades enzimáticas de ß-N-acetilglucosaminidase, quitobiosidase e uma pequena quantidade de exo-quitinase e endo-quitinase foram observadas. O extrato da FES foi utilizado para degradar parcialmente diferentes quitosanas com fração molar de N-acetilglicosamina (FA) de valor 0,27 ou 0,56, e uma quitosana cormecial com FA em torno de 0,15. Os AGO's produzidos foram caracterizados por cromatografia em camada delgada e espectrometria de massa. Uma metodologia para separação de padrões oligoméricos acetilados e desacetilados por cromatografia líquida com detecção amperométrica pulsada dos oligossacarídeos foi desenvolvida e otimizou-se a hidrólise enzimática para produção dos AGO's de quitosanas. Hetero-oligômeros bioativos com grau de polimerização entre 2 e 7 foram produzidos, apresentando atividade antimicrobiana em Pseudomonas syringae e potencializando a explosão oxidativa em células de arroz, utilizando quitosana como elicitor (ambas atividades foram encontradas em concentrações de 50 µg/mL de AGO's) / Abstract: Studies on chitin and chitosan have drawn interest because of their possible conversion into oligosaccharides, which are water-soluble and present attractive biological activities. To this end, cost effective methods for the production of potentially bio-active chito-oligosaccharides (COS) are required. In this work we decided to study the feasibility of using solid state fermentation (SSF) for the production of a suitable enzyme extract for the eventual obtention of COS. The first step was the identification of a suitable fungus for solid satet fermentation (SSF) using shrimp shells as a substrate, and a strain of Trichoderma polysporum was eventually selected. The second step involved the optimisation of growth conditions to obtain enzyme preparations capable of producing COS with degrees of polymerisation of at least 5, this typically being the minimum DP for reliable bio-activities. The SSF extract was used to partially degrade different well characterised chitosans with a molar fraction of N-acetylglucosamine (FA) value of 0.27 or 0.56, and a commercial chitosan obtained from Sigma (FA around 0.15). The chitosanolytic enzymes produced by T. polysporum under different fermentation conditions were analysed by electrophoresis followed by activity staining and the enzyme activities of ß-N-acetylglucosaminidase, chitobiosidase and a small amount of exo-chitinase and endo-chitinase were observed. After hydrolysis, the complex mixture was precipitated, and the supernatant containing the COS produced was analysed using thin layer chromatography (TLC) and quadrupole time-of-flight tandem mass spectrometry. We detected the presence of chitinase rather than chitosanase activity and the production of hetero-oligomers with degrees of polymerisation between 2 and 7. The bio-activity of these oligomer mixtures in rice plants cells and against the growth of Pseudomonas syringae was founded / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química
52

PRODUÇÃO DE BIOETANOL A PARTIR DE RESÍDUOS LIGNOCELULÓSICOS POR FERMENTAÇÃO EM ESTADO SÓLIDO / BIOETHANOL PRODUCTION FOR LIGNOCELULOSIC BIOMASS BY SOLID STATE FERMENTATION

Canabarro, Nicholas Islongo 20 February 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The energy crisis caused by the exhaustion of fossil fuels and environmental problems has caused concerns of researchers and, consequently, causing them to seek alternatives to replace fossil fuels with renewable sources. An interesting alternative is the use of solid-state fermentation for biofuels production using agricultural residues as a source of fermentable sugars. In Rio Grande do Sul, about 10 million tons of rice a year are produced in the state, producing around 3 million tons of rice husk and 1.5 million tons of rice bran. Such wastes have great potential for the production of bioethanol, but there are no proper techniques to date for the industrial production of ethanol by these wastes. The ethanol extraction technique from the solid state fermentation process is techniques should be improved so that the process becomes efficient and environmentally friendly. Thus, in this work was carried out a preliminary step to ethanol production process by solid state fermentation, evaluating an ethanol extraction method using distilled water as solvent. In this step, we evaluated parameters influencing the fermentation process (moisture content and initial concentration of ethanol) and the extraction process (temperature, agitation and solid-liquid ratio). Set the extraction conditions, the experimental design methodology was used in order to identify the significant variables in the process of solid state fermentation for ethanol production through the application of a design Plackett & Burmann experiments. The response surface methodology was used to perform process optimization, based on the evaluation of a central composite rotational design (CCRD). For end a scale-up of the simultaneous saccharification and solid state fermentation process was proposed, reaching a final ethanol concentration of 143.88 g EtOH / kg substrate. / A crise energética causada pela exaustão de combustíveis fósseis e problemas ambientais tem causado preocupações de pesquisadores e, consequentemente, fazendo com que os mesmos procurem alternativas para substituir os combustíveis fósseis por fontes renováveis. Uma alternativa interessante é o uso da fermentação em estado sólido para produção de biocombustíveis, utilizando resíduos agroindustriais como fonte de açúcares fermentáveis. No Rio Grande do Sul, cerca de 10 milhões de toneladas de arroz são produzidas por ano no Estado, produzindo em torno de 3 milhões de toneladas de casca de arroz e 1,5 milhão de toneladas de farelo de arroz. Tais resíduos apresentam grande potencial para a produção de bioetanol, porém não há técnicas adequadas até o momento para a produção industrial de etanol através destes resíduos. A técnica de extração de etanol proveniente do processo de fermentação em estado sólido é uma das técnicas que devem ser aprimoradas para que o processo se torne eficiente e ambientalmente correto. Com isso, neste trabalho foi realizada uma etapa preliminar ao processo de produção de etanol por fermentação em estado sólido, avaliando um método de extração de etanol utilizando água destilada como solvente. Nesta etapa, foram avaliados parâmetros que influenciam o processo fermentativo (teor de umidade, e concentração inicial de etanol) e o processo de extração (temperatura, agitação e razão sólido-líquido). Fixadas as condições de extração, a metodologia de planejamento de experimentos foi utilizada com objetivo de identificar as variáveis significativas no processo de fermentação em estado sólido para a produção de etanol, através da aplicação de um design de experimentos Plackett & Burmann. O método de superfície de resposta foi utilizado para realizar a otimização do processo, com base na avaliação de um delineamento composto central rotacional (DCCR). Por fim, foi proposto um aumento de escala do processo de sacarificação e fermentação simultânea em estado sólido, atingindo uma concentração de etanol final de 143,88 g EtOH/ kg substrato.
53

Produção de aroma de coco por Trichoderma harzianum utilizando bagaço de cana

Calasans, Patricia Nunes 13 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Biotechnology is inserted within the search for new products and processes, thus becoming an important tool in the development of biotechnological natural aroma production processes. Flavors compounds obtained from these processes represent a very promising and viable way of production for industries mainly due to the increase of consumer preference for natural food additives and products. Many microorganisms isolated from various environments have potential to synthesize flavors compounds when cultivated in an appropriate culture medium. Fermentation processes allow the use of agro-industrial wastes in which disposal on the environment may cause serious pollution issues. The residues composition, mostly the carbon source, allows the growth of microorganisms and the production of higher aggregate value compounds. The aim of this work is the to produce and quantify the 6-pentyl-á-pyrone lactone, responsible for the coconut-like aroma, by using agro-industrial waste as support and the filamentous fungus Trichoderma harzianum. Initially three agro-industrial wastes (sugarcane bagasse, coconut shell powder and cassava bagasse) were tested concerning the aroma production. Then the gas chromatography coupled to headspace extraction technique provided the quantitative and qualitative analysis of the lactone. Through the chromatogram area, the 4040 strain of Trichoderma fungus and the cassava bagasse were selected as culture medium. The latter was studied by the physical chemistry aspect. The tests done in order to evaluate the microorganism lactone toxic level did not show a complete inhibition in cell growth, only a few spores. The total factorial design in two levels was applied to verify the influence of the nutrients concentration (C/N) and temperature in the production of 6-pentyl-á-pyrone. The largest production of aroma compound resulted in 3.78 mg/g MS at the 7th culture day. The linear and quadratic terms related to temperature were important to the proposed model at a 95% trust level for aroma maximum concentration, by setting values between 25 and 28°C. The C/N ratio effect and the interaction between these two variables were not statistically meaningful. / A biotecnologia se insere na busca de novos produtos e processos, tornando-se uma ferramenta importante no desenvolvimento de processos de produção de aromas naturais biotecnológicos. Compostos de aroma obtidos por estes processos representam uma alternativa de produção bastante promissora e viável para as indústrias, principalmente devido ao aumento da preferência dos consumidores por aditivos alimentícios e produtos naturais. Muitos microrganismos, isolados dos mais variados ambientes, possuem potencial para sintetizar compostos de aroma quando cultivados em meios de cultura adequados. Os processos fermentativos possibilitam o aproveitamento de resíduos agroindustriais, cuja disposição no meio ambiente gera sérios problemas de poluição. A composição dos resíduos, principalmente a fonte de carbono, permite o crescimento dos microrganismos e produção de compostos de maior valor agregado. O presente trabalho tem como objetivo produzir e quantificar a lactona 6-pentil-á-pirona, responsável pelo aroma característico de coco, utilizando resíduo agroindustrial como suporte e fungo filamentoso Trichoderma harzianum. Inicialmente, três resíduos agroindustriais (bagaço de cana, pó da casca de coco e bagaço de mandioca) e cinco microrganismos foram testados quanto à produção do aroma. A técnica de cromatografia gasosa acoplada à extração em headspace permitiu as análises qualitativas e quantitativas da lactona. Através da área do cromatograma, a linhagem 4040 do fungo Trichoderma e o suporte bagaço de cana foram selecionados como meio de cultivo. O resíduo bagaço de cana foi caracterizado sob o aspecto físico-químico. Os testes realizados para avaliar o nível de toxidez da lactona sobre o microrganismo não apresentaram inibição total no crescimento celular, apenas pouca presença de esporos. O planejamento fatorial completo em dois níveis foi empregado para avaliar a influência da concentração de nutrientes (C/N) e da temperatura sobre a produção do 6-pentil-á-pirona. A maior produção do composto de aroma resultou em 3,78 mg/g MS no 7º dia de cultivo. Os termos lineares e quadráticos relacionados à temperatura foram significativos no modelo proposto a um nível de confiança de 95% para a máxima concentração do aroma, sendo direcionadas para valores de 25 a 28ºC. O efeito da razão C/N e de interação entre as duas variáveis não foram estatisticamente significativos.
54

Produção de celulases e xilanases pelo fungo Aspergillus labruscus ITAL 22.223 cultivado em fermentação em estado sólido utilizando resíduos agroindustriais /

Maestrello, Chadia Chahud. January 2018 (has links)
Orientador: Luis Henrique Souza Guimarães / Banca: Daniela Alonso Bocchini / Banca: Valéria de Carvalho Santos Ebinuma / Resumo: A prospecção de enzimas fúngicas tem sido amplamente estudada nos ultimos anos, principalmente utilizando a Fermentação em Estado Sólido (FES). A procura por enzimas microbianas, principalmente de fungos filamentosos, capazes de degradar material lignocelulósico, tem despertado grande interesse para processos biotecnológicos como, por exemplo, na produção de bioetanol, a partir do bagaço de cana-de-açúcar. Fungos do gênero Aspergillus são reconhecidos como ótimos produtores de enzimas do complexo celulolítico e hemicelulolítico, e a busca por novas linhagens com potencial de produção destas torna-se um grande desafio. Aspergillus labruscus ITAL 22.223 é um fungo filamentoso recentemente isolado no sul do Brasil e, por este motivo, não há estudos na literatura sobre seu potencial de produzir enzimas celulolíticas e hemicelulolíticas. Diante do exposto, este estudo visou a produção e quantificação de enzimas do complexo celulolítico (celulase total, endoglucanase e β-glicosidase) e hemicelulolítico (xilanase), a partir de fermentação em estado sólido utilizando resíduos/produtos agroindustriais como substratos. Neste contexto, a maior atividade enzimática de xilanase foi obtida na presença de farelo de trigo (74,83 U/g de substrato) e de β-glicosidase em farelo de aveia (6,35 U/g de substrato) como substratos/fontes de carbono. Sendo a produção de xilanase em FES a que mais se destacou, algumas características da enzima contida no extrato bruto foram determinadas. Apresentou te... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Prospecting of fungal enzymes has been largely studied in recent years, especially by means of Solid-State Fermentation (SSF). The search for microorganisms' enzymes able to degrade lignocellulosic material, mainly those of filamentous fungi, has attracted interest for application in biotechnological processes, such as in production of cellulosic ethanol from sugarcane bagasse. Aspergillus species are well known for their capability to produce cellulosic and hemicellulosic enzymes complex and the search for strains with this potential is an important challenge. Aspergillus labruscus ITAL 22.223 is a filamentous fungus recently isolated in south of Brazil with unknown potential to produce cellulolytic or hemicellulolytic enzymes. This study aimed the production and quantitation of enzymes of the complex cellulolytic (total cellulose, endoglucanase and and β-glucosidase) and hemicellulolytic (xylanse) obtained under solid-state fermentation using agroindustrial waste and product as substrates. According to this, the greatest enzymatic productions of xylanase (74.83 U/g of substrate) and β-glucosidase (6.35 U/g of substrate) were obtained using wheat bran and oat bran as substrates during SSF fermentation, respectively. Taking in account the best production of xylanase in SSF, some biochemical characteristics were determined for the enzyme contained in the crude extract. Optimal of temperature for enzyme activity was 55ºC and optimal pH was 5.5. Regarding its thermal stability, ... (Complete abstract click electronic access below) / Mestre
55

Využití odpadů rostlinného původu / Utilization of plant origin waste

Habáníková, Kamila January 2010 (has links)
Production of cellulase and polygalacturonase by Aspergillus niger and Aureobasidium pullulans was studied in submerged (SmF) and solid state fermentation (SSF) systems. Substrates used in fermentation systems were mandarin peels and grape pomace. With Aspergillus niger used on grape pomace as a sole carbon source, cellulase production was detected after 72 hours in SSF and after 24 hours in SmF systems. The activity of cellulase per gram of substrate was higher in a submerged than in a solid state fermentation system. The longer time for higher polygalacturonase production was necessary in submerged fermentation systems and polygalacturonase activity was higher in SmF. The SSF fermentation with mandarin peels as a sole carbon source was similar, the highest detected activity of cellulase was determined after 72 hours. Different production of polygalacturonase was observed on mandarin peels in SmF systems. A comparison of enzyme productivities on grape pomace and mandarin peels showed that polygalacturonase activity per gram of substrate is highest in SmF system with mandarin peels as a sole carbon source. With Aureobasidium pullulans used on grape pomace as a sole carbon source, cellulase production was detected after 48 hours in SmF and SSF fermentation systems. The activity of cellulase per gram of substrate was higher in solid state system than in a submerged fermentation system. Longer time for higher polygalacturonase production was necessary in both fermentation systems. Polygalacturonase activity was higher in SmF. The SSF fermentation with mandarin peels as a sole carbon source was similar, the highest detected activity of cellulase was determined after 48 hours. Different production of polygalacturonase was observed on mandarin peels in SmF systems. A comparison of enzyme productivities on grape pomace and mandarin peels showed that polygalacturonase activity per gram of substrate is highest in SmF system with mandarin peels as a sole carbon source. For both systems and both substrates manganese-dependent peroxidase was detected for the first time. Differences in the enzyme synthesis by Aspergillus niger and Aureobasidium pullulans depend on both the substrates used as well as on the fermentation system.
56

Uppskalning av en svampkaka : process från avfallsbröd med en ätlig svamp / Scaling up a Fungal Cake : Process from Waste Bread Using an Edible Fungus

Ricky, Ricky January 2020 (has links)
Stale bread contributes to the biggest volume of food waste in Sweden. Current method on recovering bread waste is by producing biogas or bioethanol. Despite advantages in the energy sector, the bread which still has relatively high quality could be recovered into new products with higher value, such as food for human consumption. Development of a product, termed ‘fungal cake’ by solid state fermentation on bread waste using Neurospora intermedia in small scale petri dishes have previously been successfully conducted. This study aims to scale up the production of fungal cake into bench scale production. Two systems using different bioreactors were used in this study. The first system operated in batch mode using a tray bioreactor, in which the effect of particle size, mixing, and bread loading were evaluated. The fermentation was conducted during 5 days. Bread crumb with a larger particle size of 2 mm resulted in similar outcomes as bread crumb with a smaller particle size of 0.5 mm in terms of CO2 evolution rate, cumulative CO2 production, starch, and protein content of the final product. However, larger particle size resulted in a more homogeneous growth of the fungus throughout the product, which is preferred. The presence of daily mixing had no significant effect compared to static condition for all measured variables. Thus, mixing could be introduced to promote product homogeneity. Likewise, bread loading had no significant effect on the measured variables, which implies that a higher productivity can be achieved using a higher bread loading. The second system operated in continuous mode using a newly developed continuous tubular bioreactor with product recycle. Two experiments, in which the residence time (48h and 24h) and recycle ratio (10/65 and 20/55) were conducted. Both experiments yielded product with stable starch and protein content, indicated by a stable CO2 evolution rate over time. The performance using continuous tubular bioreactor was compared to batch fermentation in tray bioreactor using the same ratio of inoculum and both system yielded product with the same starch and protein content. Successful operation in continuous bioreactor certainly improved the productivity of fungal cake production.
57

Solid State Fermentation in a Spouted Bed Reactor and Modelling Thereof

Bennett, Patrick M. January 2013 (has links)
No description available.
58

Production d’acide itaconique par des souches d’Aspergilli par fermentation en milieu solide / Itaconic acid production by Aspergillus strains by solid state fermentation

Restino, Clémence 05 December 2012 (has links)
Depuis quelques années, un des défis de la Recherche est de valoriser les co-produits agro-industriels. Une des voies permettant la valorisation de ces « déchets » est la fermentation en milieu solide.Le but de ce travail est de produire de l'acide itaconique par des souches d'Aspergilli (Aspergillus itaconicus et Aspergillus terreus) à partir de ressources renouvelables. Le substrat choisi dans cette étude est le son de blé, coproduit largement disponible en Champagne-Ardenne.L'acide itaconique a été classé dans le TOP 12 des molécules plateformes par le Department Of Energy Américain. Ces molécules plateformes peuvent être produites à partir de biomasse ligno-cellulosique et peuvent être utilisées à la place de molécules d'origine pétrochimique.Dans notre étude, nous n'avons pas mis en évidence de production d'acide itaconique par la souche Aspergillus terreus NRRL 1960 mais nous avons observé, pour la première fois, la production d'acide fumarique par fermentation en milieu solide. L'acide fumarique est tout aussi intéressant que l'acide itaconique puisqu'il fait également partie du TOP 12 des molécules plateformes. La production maximale obtenue est de 0,44 mg/g de matière sèche par fermentation en milieu solide sur son de blé humidifié à 70% et à pH 3, après 5 jours d'incubation à 30°C.De plus, nous avons montré qu'Aspergillus itaconicus NRRL 161 est capable de produire 6,77 mg d'acide itaconique/g de matière sèche par fermentation en milieu solide sur son de blé humidifié à 60% par une solution de saccharose à 400 g/L et à pH 3, après 4 jours d'incubation à 30°C.Dans une dernière partie, nous avons mis en évidence, chez Aspergillus itaconicus NRRL 161, la présence potentielle du gène codant pour la Cis-Aconitic acid Decarboxylase, enzyme clé dans la production d'acide itaconique. / Since a few years, one of research's challenges is to valorise agro-industrial by-products. One of the ways permitting the valorisation of these “wastes” is solid-state fermentation.The aim of this work is to produce itaconic acid with Aspergilli (Aspergillus itaconicus and Aspergillus terreus) strains from renewable resources. The chosen substrate in this study is wheat bran, by-product widely available in Champagne-Ardenne.Itaconic acid is classified among the TOP 12 of building blocks by the American Department Of Energy. Building blocks can be produced from ligno-cellulosic biomass and can be used instead of petrochemical-based molecules.In our study, we have not highlighted itaconic acid production by Aspergillus terreus NRRL 1960, but we have observed fumaric acid production by solid state fermentation. Fumaric acid is as interesting as itaconic acid since it also belongs to the TOP 12 of building blocks. Maximal production of fumaric acid is 0.44 mg/g dry matter by solid-state fermentation on wheat bran moistened at 70% and at pH 3, after 5 days of incubation at 30°C.Furthermore, we have shown that Aspergillus itaconicus NRRL 161 is able to produce 6.77 mg of itaconic acid/g dry matter by solid state fermentation on wheat bran moistened at 60% with sucrose solution at 400 g/L and at pH 3, after 4 days of incubation at 30°C.In a last part, we have highlighted, in Aspergillus itaconicus NRRL 161, the potential presence of the Cis-Aconitic acid Decarboxylase encoding gene, key enzyme in itaconic acid production.
59

Distribution des moisissures post-récolte et action antifongique des bactéries lactiques isolées du blé dur en Tunisie

Belkacem, Nesrine 16 December 2013 (has links)
Au cours du stockage et sous de mauvaises conditions de conservation, les grains de blé peuvent subir diverses altérations causées par le développement fongique. Les moisissures peuvent produire des toxines pouvant avoir un impact sur la santé du consommateur. L’évaluation de la diversité fongique sur blé de stockage produit localement dans les régions céréalières du Nord de la Tunisie durant deux années successives (2010-2011 et 2011-2012) a montré une dominance du genre Alternaria. L’étude de la cinétique d’évolution de cette mycoflore au cours du stockage s’est caractérisée par un profil particulier dépendant des paramètres géographiques et temporels et des conditions écophysiologiques. L’évaluation du pouvoir toxinogène a révélé un faible pourcentage d’isolats ochratoxinogènes. L’évaluation de la présence de l’OTA dans le blé ont montré des taux de contaminations largement inférieurs aux normes européennes. L’étude sur la physiologie de sporulation et la production d’OTA en Fermentation en Milieu Solide par A. carbonarius à montré une amplification de la production des conidiospores et de l’OTA par aération humide forcée. L’évaluation de l'activité antifongique de 15 bactéries lactiques isolées du blé de stockage à l’égard de 8 moisissures post-récolte a montré une bonne aptitude de Lb. plantarum à inhiber la croissance de ces moisissures. L’étude du pouvoir anti-ochratoxinogène de Lb. plantarum LabN10, Lb. graminis LabN11 and P. Pentosaceus LabN12 ont montré un effet significatif de la température, du pH et de la biomasse bactérienne sur l’inhibition de la biomasse fongique ainsi que sur la réduction d’OTA. / During storage and under bad storage conditions, wheat grains can undergo various alterations caused by fungal growth. Molds can produce toxins that can have an impact on consumer health. Assessment of fungal diversity on wheat storage locally produced cereal in northern Tunisia during two successive years (2010-2011 and 2011-2012) showed a dominance of the genus Alternaria. Study of kinetics evolution of mycoflora during storage is characterized by a particular pattern depending on geographic and temporal parameters and ecophysiological conditions. Evaluation of toxigenic fungal revealed a low percentage of ochratoxinogenic isolates. Occurence of OTA in wheat showed contamination levels under European standards. The study on sporulation physiology and production of OTA by Solid State Fermentation by A. carbonarius shown amplification and production of conidiospores OTA wet forced by aeration. The evaluation of the antifungal activity of lactic acid bacteria (LAB) isolated from the 15 wheat storage against 8 post-harvest molds showed good ability of Lb. plantarum to inhibit the growth of these fungi. The study of anti-ochratoxinogène activity Lb. LabN10 plantarum, Lb. and P. graminis LabN11 LabN12 pentosaceus showed a significant effect of temperature, pH and the bacterial biomass on the inhibition of the fungal biomass and on the reduction of OTA.
60

Mise au point d'un bioréacteur de fermentation en milieu solide fonctionnant en continu pour la production de métabolites secondaires antioxydants par Aspergillus niger G131 / Development of a continuous pilote-scaled bioreactor for the production of antioxidant secondary metabolites by Aspergillus niger G131 using solid state fermentation

Carboué, Quentin 04 June 2018 (has links)
Aspergillus niger souche G131 est un champignon qui produit en quantité des métabolites secondaires appartenant à la famille des naphtho-gamma-pyrones (NγPs). Ces NγPs sont des pigments qui présentent des intérêts industriels de par leurs importants potentiels antiradicalaires. L’objectif de ce doctorat est la production à l’échelle pilote et en continu de NγPs à travers la culture du champignon sur milieu solide. Le choix de la fermentation en milieu solide (FMS) comme processus de culture repose sur des aspects d’ordre qualitatif et quantitatif de production, ainsi que sur des raisons économiques et éthiques, relatives à la protection de l’environnement avec notamment la possibilité de valoriser des coproduits agricoles comme milieu de culture pour le champignon. Dans un premier temps, ce travail s’intéresse à la caractérisation de la composition et des potentialités associées aux molécules produites par la souche. Ces potentialités incluent les activités anti-radicalaires et les mesures de cytotoxicité. La thèse porte également sur la caractérisation de la physiologie de croissance de la souche en FMS et sur l’optimisation des conditions de culture par la méthodologie des plans d’expériences pour l’augmentation de la production de NγPs. Une stratégie originale d’optimisation adaptée aux contraintes posées par la FMS est d’ailleurs proposée. Finalement, un transfert d’échelle de production est réalisé au moyen d’un bioréacteur prototype innovant permettant la production à l’échelle pilote de milieu fermenté en continu. Dans son dernier chapitre, ce travail s’intéresse donc à la mise au point des paramètres opératifs qui entourent la production continue de NγPs par FMS. / Aspergillus niger strain G131 is a non-ochratoxigenic filamentous fungus producing high quantities of secondary metabolites known as naphtha-gamma-pyrones (NγPs). NγPs are pigments of industrial interest in reason of their high antioxidant properties. The aim of this dissertation is the continuous, pilote-scaled production of these NγPs through the cultivation of the fungus on solid medium. The choice of solid state fermentation (SSF) as cultivation method is not only driven by quantitative and qualitative considerations, but also by economical and ethical concerns related to environmental protection. SSF allows, in fact, a direct valorization of agricultural byproducts as the solid medium for the fungal growth. First, this work deals with the characterization of the composition and potentialities associated with the molecules produced by the strain, which include antioxidant and cytotoxic activities. Second, the dissertation focuses on the characterization of the fungal growth’s physiology on solid medium and on the optimization of the culture conditions using experimental methodology in order to increase NγPs production. For this purpose, an original optimization strategy is proposed to overcome specific constraints connected to SSF. Finally, a scale transfer of the production is advanced by means of an innovative prototype bioreactor continuously producing fermented material. The final chapter of this work addresses the development of parameters regarding the continuous NγPs production using SSF.

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