Lactate prevents Salmonella enterica biofilm formation by inhibiting curli and cellulose expression

Salmonella enterica serovar Typhimurium (S. Typhimurium) infection triggers an inflammatory response that changes the concentration of luminal metabolites in the gut, resulting in a distinct environment from a healthy one. We recently demonstrated that S. Typhimurium possesses the ability to form biofilms within the host environment and responds to nitrate as a signaling molecule, enabling it to modulate the transition between sessile and planktonic states. To investigate whether S. Typhimurium utilizes additional metabolites to regulate its behavior, our study delved into the impact of inflammatory metabolites on biofilm formation. Employing a transcriptomic approach we unveiled that lactate enhances the transcription of flagella and invasion genes, highlighting the active role of lactate in modulating the transition of S. Typhimurium from biofilm to motile states. All these findings propose that, as occurring with nitrate, lactate is an inflammatory metabolite being used by S. Typhimurium to support virulence. Salmonella enterica samples were incubated with or without the adition of lacate (30mM) in no-salt LB at 28°C with no agitation for 18hs. RNA were extracted from cell pellets in triplicate.