Deciphering the mechanisms of action underlying probiotic properties of Shouchella clausii by a functional genomics approach

What is it about?

Shouchella clausii (formerly named Bacillus clausii), a spore-forming bacterium is commercially available as a probiotic for the prevention and the treatment of intestinal dysbiosis and related gastrointestinal disorders, such as diarrhea. Several studies have demonstrated that S. clausii treatment modulated inflammatory and immune responses, as well as gut barrier functions, however the mechanisms of action remained poorly understood. In the present paper, we implemented a high throughput functional genomic strategy to decipher the mechanisms by which S. clausii exerts its probiotic effects on human intestinal epithelial cells. Large genomic DNA fragment libraries were constructed for four strains of S. clausii, namely the O/C, N/R, SIN and T stains. A high throughput in vitro screening in human epithelial cells was then conducted, using the reporter gene strategy, targeting the NF-kB pathway and Interleukin-10 gene expression. After an exhaustive in vitro screening of approximately a thousand clones per library, followed by transposon mutagenesis, a new campaign of screening and sequencing of hits, we identified 23 coding sequences including one encoding the Glutamine Synthetase gene that were associated with NF-B signaling pathway modulation, and six CDS for modulation of IL-10 expression. These functional genomic strategy that was applied to S. clausii is an innovative approach to identify gene candidates that may explain the mechanisms of action of probiotics.

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