Dynamic interplay: chemotaxis, quorum sensing and metabolism affect Escherichia coli interactions during gut colonization

Bacteria communicate and coordinate their behavior at the intra- and inter-species levels by producing and sensing extracellular small molecules called autoinducers. Autoinducer 2 (AI-2) is produced and detected by a variety of bacteria, thus playing an important role in interspecies communication. Although AI-2 is a major autoinducer molecule present in the mammalian gut, its role in bacteria-bacteria and bacteria-host interactions during gut colonization remains unclear. Through competitive infections in C57BL/6 mice, along with microscopy and bioinformatic approaches, we show that chemotaxis and AI-2 signalling promote gut colonization by Escherichia coli, which is in turn connected to the ability of the bacteria to utilize fructoselysine. Additionally, we show that the genomic diversity of E. coli strains with respect to AI-2 signaling allows ecological niche segregation and stable co-existence of different E. coli strains in the mammalian gut.

Furthermore, we demonstrate that E. coli competes with enteric pathogen Salmonella Typhimurium in AI-2 chemotaxis-dependent manner. Utilizing a genetically tagged library of S. Tm gene knockouts, we conducted high-throughput analysis to identify metabolic genes that contribute to E. coli-S. Tm competition during the murine gut colonization. Preliminary data suggests the involvement of genes related to glycerol metabolism and fumarate respiration. In summary, our results pinpoint the importance of quorum sensing- and metabolic pathways involved in both intra- and inter-species interactions of E. coli during gut colonization.

Reference: Laganenka, L. et al. 2022. Chemotaxis and autoinducer-2 signalling mediate colonization and co-existence of Escherichia coli strains in the murine gut // Nat Microbiol. 8 (2), 204-217. doi: 10.1038/s41564-022-01286-7.