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Prospecting and induction of antimicrobial molecules by co-culture between bacteria (Streptomyces) and fungi (Basidiomycota)and fungi (Basidiomycetes)

Abstract : The emergence of multiple resistance to antibiotics in pathogenic microorganisms poses a significant threat to human health. The identification of new active ingredients with cellular targets and original mechanisms is an urgent need and in this sense soil microorganisms (bacteria and fungi) rich in biological molecules constitute a reservoir of interest. During this thesis, we were interested in jointly isolated strains (community) of Streptomyces, filamentous bacteria from the soil producing more than half of the antibiotics used in medicine. A joint analysis of the metabolome and the genome of 8 strains (5 of which were sequenced during this study) showed a significant diversity of the biosynthetic pathways of specialized metabolites within this community. In order to stimulate the expression of new cryptic molecules under laboratory conditions, the co-culture of these Streptomyces and fungi was performed. A screening of 64 co-cultures between 8 strains of Streptomyces and 8 species of Basidiomycetes fungi was performed by monitoring induced antimicrobial, anti-inflammatory and anti-oxidant activities (i.e. produced in co-culture but not in cultures only bacteria and fungi). Our screens revealed two promising interactions whose products were analyzed by the combination of a metabolomics approach coupling gas chromatography, mass spectrometry (GC-MS), liquid chromatography and tandem mass spectrometry (LC-MS / MS). Antimicrobial activity-guided fractionation has identified a set of candidate compounds related to antimicrobial activity. By revealing a large variability of genes for the biosynthesis of biological molecules, our results first allowed us to define the community as an appropriate sampling framework to search for biological molecules of interest in Streptomyces. As these genes are mostly cryptic under laboratory conditions, we were also able to underline the interest of co-culture as a biotic stimulus allowing their production, making it a promising approach in biotechnology.
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Submitted on : Monday, March 22, 2021 - 3:36:19 PM
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  • HAL Id : tel-03176660, version 1

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Matthieu Nicault. Prospecting and induction of antimicrobial molecules by co-culture between bacteria (Streptomyces) and fungi (Basidiomycota)and fungi (Basidiomycetes). Ecology, environment. Université de Lorraine, 2020. English. ⟨NNT : 2020LORR0194⟩. ⟨tel-03176660⟩

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