Identification d’un nouvel enzyme par criblage fonctionnel d’une banque d’ADN génomique réalisée à partir des colonies isolées du tube digestif de termites Reticulitermes santonensis

Poster (2010, November 06)

Vinegar Starter Production

Speech (2010)

Submerged fermentation is used extensively for production of vinegar in industrial manner. One of the main technological gaps in this kind of fermentation is the lack of efficient and cost effective ... [more ▼]

Submerged fermentation is used extensively for production of vinegar in industrial manner. One of the main technological gaps in this kind of fermentation is the lack of efficient and cost effective starter culture. So far, vinegar is one of the fermented beverages produced without selected starter cultures (SSC) inoculation. In this speech, the technical problems are discussed encountered during production of starter production. [less ▲]

La production de biohydrogène à partir de substrats carbohydratés: Etat de l’art

Poster (2010, October 14)

Caractérisation de la diversité des organismes symbiotiques et des activités glycosyl hydrolases dans le tube digestif de Reticulitermes santonensis (Feytaud) par une approche multidisciplinaire

Scientific conference (2010, July 08)

Le bioéthanol cellulosique pourrait être une solution pour satisfaire le besoin croissant en énergie renouvelable. Actuellement, l’efficience de la transformation de la cellulose en sucres fermentescibles ... [more ▼]

Le bioéthanol cellulosique pourrait être une solution pour satisfaire le besoin croissant en énergie renouvelable. Actuellement, l’efficience de la transformation de la cellulose en sucres fermentescibles reste le principal facteur limitant. La recherche de nouvelles glycosyl hydrolases constitue une voie potentielle d’amélioration de la valorisation des composés ligno-cellulosiques. Trois types de glycosyl hydrolases sont généralement produites par les organismes capables d’utiliser efficacement ces composés : les endoglucanases, les exoglucanases/cellobiohydrolases, et les β-glucosidases. Dans les processus de digestion de la cellulose par les animaux, des organismes symbiotiques tels que des bactéries, des protistes et/ou des champignons sont fréquemment observés. Ces organismes contribuent en grande partie voir totalement à la production des complexes enzymatiques nécessaires. Chez les termites inférieures, comme notre modèle Reticulitermes santonensis (Feytaud), des protistes et des bactéries sont impliqués dans un système symbiotique complexe. Une étude multidisciplinaire est menée afin d’approfondir les rôles respectifs des différents groupes de symbiontes, via des approches « omiques », à savoir la protéomique (ESI-LC-MS-MS, 2D-SDS-PAGE couplée avec une analyse en spectrométrie de masse du type MALDI-TOF pour l’identification des protéines), la génomique (avec une approche métagénomique basée sur la construction d’une large banque de cDNA), la métabolomique (caractérisation des produits de dégradation de carbohydrates via une strategie LC-MS). De plus, l’isolation de microorganismes a également été employée dans la caractérisation de la diversité et de l’activité des glycosyl hydrolases chez R. santonensis. [less ▲]

The Resistance to Freeze-Drying and to Storage Was Determined as the Cellular Ability to Recover Its Survival Rate and Acidification Activity

in International Journal of Microbiology (2010), 2010(625239),

The protective effects of the fatty acid composition and membrane action of the acidification activity of two strains of Lactobacillus kept at 20◦C were studied. The addition of sorbitol, monosodium ... [more ▼]

The protective effects of the fatty acid composition and membrane action of the acidification activity of two strains of Lactobacillus kept at 20◦C were studied. The addition of sorbitol, monosodium glutamate and glycerol during storage is causing the decline of acidification and increased concentrations of unsaturated fatty acids observed in both strains. The addition of sorbitol and monosodium glutamate does not alter the fatty acid composition, whatever the strain, but increases the resistance to freeze-drying of L. plantarum CWBI-B1419 and improves survival during storage. The addition of these preservatives and decreased activity of acidification improves the ratio unsaturated. These results indicate that the survival during storage and freeze-drying resistance are closely related to the composition of membrane fatty acids. This behaviour can be interpreted as an adaptation of L. plantarum B1419-CWBI supplemented by cryoprotectant additives such as sorbitol or monosodium glutamate sorbitol and monosodium glutamate as an additive. L. plantarum CWBI-B1419 presents a greater adaptation to culture conditions than L. paracasei ssp. paracasei LMG9192T. [less ▲]

Integrated “omics” approaches to investigate the chemical aspects of symbiosis in termites and potential application in ligno-cellulosic use.

Scientific conference (2010, May 05)

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars ... [more ▼]

Cellulosic bioethanol could be one of the solutions to satisfy the increasing demand in renewable energy. The most limitative problem is the efficiency of cellulose transformation into fermentable sugars. Investigations to select new glycosyl hydrolases are an interesting approach that constitutes a potential opportunity to improve the valorization of lignocellulosic materials. Three major types of glycosyl hydolases are generally produced by organism’s that are able to efficiently use cellulosic compounds: the endoglucanases, the exoglucanases/cellobiohydrolases and the β-glucosidases. In the ability to transform lignocellulosic materials by animals, symbioses are generally observed with a range of micro-organisms including bacteria, protists and/or fungi that largely (or completely) contribute to the production of the needed enzymatic complexes. In termites, such active enzymes are produced in the insect digestive tract, by the termite insect itself or by symbiotic organisms. Within lower termites gut, such as in our model Reticulitermes santonensis (Feytaud), protists and bacteria are associated and involved in a complex symbiotic system. To investigate the respective role of the insect and different groups of symbionts, multidisciplinary “omics” approaches were here developed including proteomics (ESI-LC-MS-MS, 2D-Dige gel coupled with MALDI-TOF mass spectrometry for protein identification), genomics (with a metagenomic approach based on large cDNA bank construction), metabolomics (LC-MS stragety for carbohydrate degradation product characterization). Moreover, microorganism isolation was used to investigate and characterize glycosyl hydrolases diversity and activity in R. santonensis. The integration of this broad range of “omics” techniques allowed characterizing the role of symbionts in insects in a fundamental approach and to invtigate the chemical ecology of xylophagous insects but also corresponding to an efficient way to promote the selection of efficient enzymatic activities to potentially produce biofuels based on the use of existing lignocellulosic materials. [less ▲]

Salmonella in chicken : Current and developing strategies to reduce contamination at farm level

in Journal of Food Protection (2010), 73(4), 774-785

Salmonella sp. is a human pathogen that frequently infects poultry flocks. Consuming raw or undercooked contaminated poultry products can induce acute gastro-enteritis in human. Faced with the public ... [more ▼]

Salmonella sp. is a human pathogen that frequently infects poultry flocks. Consuming raw or undercooked contaminated poultry products can induce acute gastro-enteritis in human. Faced with the public health concern associated with salmonellosis, the European Union (EU) has established a European regulation forcing Member States (MS) to implement control programs aimed at reducing Salmonella prevalence in poultry production, especially at the primary production level. The purpose of the present review article is to summarise the current research and to suggest future developments in the area of Salmonella control in poultry, which may be of value to the industry in the coming years. The review will focus especially on preventive strategies that have been developed and that aim at reducing the incidence of Salmonella colonization in broiler chickens at farm level. Besides the usual preventive hygienic measures, different strategies have been investigated, like feed and drinking water acidification by organic acids and immune strategies based on passive and active immunity. Modulating the diet in terms of ingredient and nutrient composition with the intent of reducing the bird’s susceptibility to Salmonella has also been examined. Because in-ovo feeding has been shown to accelerate small intestinal development and to enhance the epithelial cell function, it could also be an efficient tool to control enteric pathogens. Microflora-modulating feed additives, like antibiotics, prebiotics, probiotics, and synbiotics, represent another field of investigation, whose success depends on the additive used. Finally, recent control methods, such as chlorate products and bacteriophages, have also been studied. [less ▲]

Effect of pH on glucose and starch fermentation in batch and sequenced-batch mode with a recently isolated strain of hydrogen-producing Clostridium butyricum CWBI1009

in International Journal of Hydrogen Energy (2010), 35(8), 3371-3378

This paper reports investigations carried out to determine the optimum culture conditions for the production of hydrogen with a recently isolated strain Clostridium butyricum CWBI1009. The production ... [more ▼]

This paper reports investigations carried out to determine the optimum culture conditions for the production of hydrogen with a recently isolated strain Clostridium butyricum CWBI1009. The production rates and yields were investigated at 30 °C in a 2.3 l bioreactor operated in batch and sequenced-batch mode using glucose and starch as substrates. In order to study the precise effect of a stable pH on hydrogen production, and the metabolite pathway involved, cultures were conducted with pH controlled at different levels ranging from 4.7 to 7.3 (maximum range of 0.15 pH unit around the pH level). For glucose the maximum yield (1.7 mol H2 mol-1 glucose) was measured when the pH was maintained at 5.2. The acetate and butyrate yields were 0.35 mol acetate mol-1 glucose and 0.6 mol butyrate mol-1 glucose. For starch a maximum yield of 2.0 mol H2 mol-1 hexose, and a maximum production rate of 15 mol H2 mol-1 hexose h-1 were obtained at pH 5.6 when the acetate and butyrate yields were 0.47 mol acetate mol-1 hexose and 0.67 mol butyrate mol-1 hexose. [less ▲]

Fermentative hydrogen production by Clostridium butyricum CWBI1009 and Citrobacter freundii CWBI 952 in pure and mixed cultures

Poster (2010, March 17)

The lipoxygenase metabolic pathway in plants: potential for industrial production of natural green leaf volatiles

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(3), 451-460

Lipoxygenase enzymatic pathway is a widely studied mechanism in the plant kingdom. Combined actions of three enzymes: lipase, lipoxygenase (LOX) and hydroperoxide lyase (HPL) convert lipidic substrates ... [more ▼]

Lipoxygenase enzymatic pathway is a widely studied mechanism in the plant kingdom. Combined actions of three enzymes: lipase, lipoxygenase (LOX) and hydroperoxide lyase (HPL) convert lipidic substrates such as C18:2 and C18:3 fatty acids into short chain volatiles. These reactions, triggered by cell membrane disruptions, produce compounds known as Green Leaf Volatiles (GLVs) which are C6 or C9-aldehydes and alcohols. These GLVs are commonly used as flavors to confer a fresh green odor of vegetable to food products. Therefore, competitive biocatalytic productions have been developed to meet the high demand in these natural flavors. Vegetable oils, chosen for their lipidic acid profile, are converted by soybean LOX and plant HPL into natural GLVs. However this second step of the bioconversion presents low yield due to the HPL instability and the inhibition by its substrate. This paper will shortly describe the different enzymes involved in this bioconversion with regards to their chemical and enzymatic properties. Biotechnological techniques to enhance their production potentialities will be discussed along with their implication in a complete bioprocess, from the lipid substrate to the corresponding aldehydic or alcoholic flavors. [less ▲]