A recently isolated human commensalEscherichia coliST10 clone member mediates enhanced thermotolerance and tetrathionate respiration on a P1 phage-derived IncY plasmid

The ubiquitous human commensalEscherichia colihas been well investigated through its model representativeE. coliK-12. In this work, we initially characterizedE. coliFec10, a recently isolated human commensal strain of phylogroup A/sequence type ST10. Compared toE. coliK-12, the 4.88 Mbp Fec10 genome is characterized by distinct single-nucleotide polymorphisms and acquisition of genomic islands. In addition,E. coliFec10 possesses a 155.86 kbp IncY plasmid, a composite element based on phage P1. pFec10 harbours multiple cargo genes such as coding for a tetrathionate reductase and its corresponding regulatory two-component system. Among the cargo genes is also the Transmissible Locus of Protein Quality Control (TLPQC), which mediates tolerance to lethal temperatures in bacteria. The disaggregase ClpG(GI)of TLPQC constitutes a major determinant of the thermotolerance ofE. coliFec10. We confirmed stand-alone disaggregation activity, but observed distinct biochemical characteristics of ClpG(GI-Fec10)compared to the nearly identicalPseudomonas aeruginosaClpG(GI-SG17M.)Furthermore, we noted a unique contribution of ClpG(GI-Fec10)to the exquisite thermotolerance ofE. coliFec10, suggesting functional differences between both disaggregases in vivo. Detection of thermotolerance in 10% of human commensalE. coliisolates hints to the successful establishment of food-borne heat-resistant strains in the human gut.

Automated summary

In this study, E. coli Fec10, a newly isolated human commensal strain, was characterized for the first time. It was found to have unique genomic features and carry a plasmid with important physiological functions. The thermotolerance of E. coli Fec10 was closely related to its ClpG(GI) disaggregase, which showed distinct biochemical characteristics compared to disaggregases in other bacteria.