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Certain molecules that are self-inducing inter-bacterial dialogue, present in food, could affect the establishment of the intestinal microbiota. This hypothesis is based on the fact that food contains bacteria capable of producing self-inducing molecules capable, by cellular communication, of modulating the composition of the intestinal microbiota of infants.
In most environments, bacteria use the Quorum-Sensing (QS) system, an intercellular communication mechanism involving signaling molecules (self-inducing, AI) such as acyl-homoserine lactones (AHLs or AI-1), self-inducing peptides (AIPs), and auto-inducer 2 (AI-2), to regulate, in a concerted manner, some of their phenotypes, notably virulence, bacteriocin production and biofilm formation. In some of the commonly consumed food products (fermented, biopreserved or containing probiotics) bacteria present in high population levels can produce AI. Studies have shown that AIs or AI-producing strains can alter the composition of the gut microbiota or reduce dysbiosis induced by antibiotic treatment.
The objective of the QSAIM project is therefore to establish proof that a dietary source of bacterial AI other than peptides can modulate the intestinal microbiota by altering its own QS system.The strategy is based on the following 4 sub-objectives:
    1) Design, produce and select two model foods (one fermented dairy product type and the other unfermented seafood type) containing varying compositions and contents of AHLs and AI-2
    2) Determine the digestive fate of AHLs and AI-2 according to the nature of the model food
    3) Characterize the impacts of 2 of these foods on the unstabilized rat microbiota
    4) Support the track of a modulation of the QS system specific to the intestinal microbiota.

SECALIM is more particularly involved in the first task which consists in the production of model foods containing AI. The design of fermented model foods will require the screening of bacterial strains commonly used as ripening starter and / or as a probiotic, preselected on the presence of genes involved in the synthesis of AIs in their genomes (eg: Lactobacillus plantarum, L. fermentum , Streptococcus thermophilus. Propionibacterium freudenreichii, Hafnia alvei ...). For the unfermented food model, the screening of the strains will be carried out from bio-preservation strains such as Lactococcus piscium which has the genes encoding the synthesis of AI-2 and produces AI-2 and strains belonging to the microbiota associated with seafood for the production of AHLs such as H. alvei. The selected strains will be used (pure culture or co-culture) to produce model foods from “salmon juice”.
Funding: INRAE, inter-departmental call for projects AlimH, CEPIA, MICA, IB
Partners: The INRAE ​​units of the INRAE ​​Pays de la Loire center, UMR Phan 1280, UR BIA 1268 and the INRAE ​​unit of the INRAE ​​Bretagne and Normandie center UMR STLO 1253.