Search results for "Bactéries"
showing 10 items of 18 documents
Le site à ambre et plantes du Cénomanien de Neau (Mayenne, France)
2020
International audience; A new Cenomanian amber- and plant-bearing deposit has been discovered at Neau, in the Mayenne department (France). The Cenomanian fossiliferous lignites are located in karst filling in a substratum of Cambrian limestones. The amber corresponds mainly to tiny millimetric grains, devoid of arthropod inclusions, but rich in microorganisms, especially the sheated bacteria Leptotrichites resinatus , and containing pollen grains ( Classopollis ) and wood fibers (Araucariacae or Cheirolepidiaceae). The lignites provide abundant conifer and ginkgoale cuticle fragments ( Frenelopsis , Eretmophyllum ) and a lot of palynomorphs ( e.g. Gleicheniidites senonicu s, Cyathidites , D…
Contribution to development of microbial bioindicators for assessing the impact of agricultural pratices on soil
2015
Soil is the support of agricultural production. It performs many functions essential to the provision of ecosystem services necessary for the well-being of our societies. Soil physicochemical and biological properties have been altered by the development of intensive agriculture while it is a non-renewable resource, revealing the need to develop new management practices suitable for the sustainability of soil quality. This also marked the entry into the “Agroecology” era, which promotes the development of new agricultural systems optimizing services provided by biodiversity to reduce the use of inputs and energy use. To achieve this aim, the development of a range of indicators to assess th…
Study of the biochemical composition and physico-chemistry of a protein-based food model of Parkia biglobosa
2022
In West Africa, the seed of the cowpea (Parkia biglobosa) is used in traditional pharmacopoeia and especially in human food as a condiment. This legume is very rich in proteins and lipids and remains a poorly exploited source of protein. Our thesis focuses on the valorization of Néré seeds for the development of new protein-rich products of plant origin as an alternative to the use of soybean as a basic ingredient. The objectives were : (i)biochemical and physicochemical characterization of protein isolates from Néré seed flour according to the extraction process, (ii) selection of proteolytic lactic acid bacteria capable of fermenting Néré juice, reducing anti-nutritional factors in order …
Lactic acid bacteria strains for bioprotection application with cells entrapment in biopolymeric matrices
2013
Among the various methods to control foodborne pathogenic and/or food spoilage microorganisms in food chain, bioprotective lactic acid bacteria (LAB) appear to be promising tools for food biopreservation. This collaborative study, between PAPC (Agrosup Dijon, University of Burgundy) and BioDyMIA (University Lyon1-Lyon Isara) laboratories, concerned the development of sodium alginate/sodium caseinate polymeric matrices intended to entrap LAB cells selected for their anti-Listeria spp. activity. First, 4 LAB strains from 19 LAB strains were selected for their anti-Listeria spp. activity: this screening was performed by the method of agar diffusion against three Listeria spp strains. Then, ant…
Revelation of aroma potential of grape pomace and spent coffee ground by the use of microbial glycosidases.
2021
The food industry is evolving and tends to reduce its environmental impact, to control its waste and to valorise all of its production. Grapes and coffee are among the main agricultural products in the world and not all of the byproducts resulting from their processing are still valued today. New ways of valorisation are seeked in order to limit production losses. Yet, these byproducts are rich in glycosides, the amount of which may be from two to five times greater than that of the free volatile compounds. Grape pomace and spent coffee ground could be used to naturally produce volatile compounds from their glycosides. These volatile compounds could be useful in the production of cosmetics,…
Effects of high pressure processing and biopreservation on the inactivation and the germination of spores of Bacillus and Clostridium
2018
Bacterial endospores are one of the most resistant life form on earth. Their capacity to survive to decontamination processes and their potential pathogenicity represent a real problem for the food industry. Currently, the only way to prevent their development in foods is the application of thermal treatments or the use of preservatives. However, these two methods have negative impacts on the nutritional properties of foods and on the consumers’ health. High hydrostatic pressure (HP) is a non-thermal process widely used for commercial pasteurization of foods. However, this process has a very low effect on spores and has therefore to be combined with other decontamination processes to enhanc…
Impact of polyphenols and feeding rhythms on the immunomodulation properties of the probiotic bacteria in the gastro-intestinal tract
2021
The human intestinal microbiota is composed of several types of microorganisms, including bacteria, archaea, fungi, unicellular eukaryotes and viruses. Among them, bacteria are the most diverse and abundant with a gene catalog 150 times larger than the genes present in the human genome, which represents a tremendous metabolic potential. These bacteria actively participate in the maintenance of intestinal homeostasis. Dysbiosis of the gut microbiota could be observed at course of many human pathologies, particularly inflammatory diseases intestinal chronic diseases (IBD), such as Crohn's disease (CD) or Ulcerative colitis (UC). These dysbiosis could contribute to the onset and progression of…
Development of methods for the detection and quantification of spoilage microorganisms in wine : study of growing factors
2016
New practices used to elaborate wine lead to an increase of wine spoilage due to microorganisms. That is why, new technics have to be developed to quantify these microorganisms accurately, quickly and with low costs. The main wine spoilages are due to acetic acid bacteria (AAB) (A. aceti, A. pasteurianus, G. oxydans and Ga. liquefaciens) and Brettanomyces bruxellensis development. AAB transforms ethanol to acetic acid while B. bruxellensis transforms hydroxycinnamic acids to ethyl phenols (EP) (unpleasant odor molecules). In order to detect these wine spoilage microrganisms, flow cytometry coupled to fluorescent in situ hybridization has been assessed. No reproducible results have been deve…
Influence of organic matters on the bacterial AsIII oxidation in polluted soils
2014
International audience; The global bacterial AsIII-oxidizing activity tends to decrease As toxicity in soils and its transfer toward underlying aquifers. The influence of different types of organic matters on arsenic speciation by pure strains and soils microflora was determined. Experimental results show that the presence of organic matter has a negative effect on the specific rate of AsIII oxidation by pure strains presenting different metabolisms. In parallel, experiments are performed with various soils from different types of polluted sites: former mining and industrial sites, forest and agricultural soils impacted by mining activities. The effect of yeast extract on the AsIII-oxidizin…
Conférence invitée : " Mécanismes et gestion de la symbiose mycorhizienne dans les agro-écosystèmes"
2017
National audience; Présentations et échanges sur les résultats de l’INRA à propos desmycorhizes : quelles stratégies développées par les plantes pour mieuxutiliser les ressources naturelles du sol ? Comment favoriser desconditions favorables à l'installation et à la vie des champignonsbénéfiques du sol ? Quelle influence la nature du sol a-t’elle sur laquantité et la diversité de champignons mycorhiziens ? Quid desintrants ? Les fongicides ont-ils vraiment un effet délétère sur leschampignons Mycorhiziens ? La résistance des plantes aux pesticidespeut-elle être favorisée par les mycorhizes ?