Gut inflammation can boost horizontal gene transfer between pathogenic and commensal Enterobacteriaceae.
The mammalian gut harbors a dense microbial community interacting in multiple ways, including horizontal gene transfer (HGT). Pangenome analyses established particularly high levels of genetic flux between Gram-negative Enterobacteriaceae. However, the mechanisms fostering intraenterobacterial HGT are incompletely understood. Using a mouse colitis model, we found that Salmonella-inflicted enteropathy elicits parallel blooms of the pathogen and of resident commensal Escherichia coli. These blooms boosted conjugative HGT of the colicin-plasmid p2 from Salmonella enterica serovar Typhimurium to E. coli. Transconjugation efficiencies of ~100% in vivo were attributable to high intrinsic p2-transfer rates. Plasmid-encoded fitness benefits contributed little. Under normal conditions, HGT was blocked by the commensal microbiota inhibiting contact-dependent conjugation between Enterobacteriaceae. Our data show that pathogen-driven inflammatory responses in the gut can generate transient enterobacterial blooms in which conjugative transfer occurs at unprecedented rates. These blooms may favor reassortment of plasmid-encoded genes between pathogens and commensals fostering the spread of fitness-, virulence-, and antibiotic-resistance determinants.
Institute of Microbiology,  ETH Zürich, 8093 Zürich,  Switzerland.
Bärbel
B
Stecher
Rémy
R
Denzler
Lisa
L
Maier
Florian
F
Bernet
Mandy J
MJ
Sanders
Derek J
DJ
Pickard
Manja
M
Barthel
Astrid M
AM
Westendorf
Karen A
KA
Krogfelt
Alan W
AW
Walker
Martin
M
Ackermann
Ulrich
U
Dobrindt
Nicholas R
NR
Thomson
Wolf-Dietrich
WD
Hardt
D000818:Animals; D003086:Bacteriocin Plasmids / Q000235:genetics; D001483:Base Sequence; D005075:Biological Evolution; D003092:Colitis / Q000382:microbiology*; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics* / Q000254:growth & development; D004926:Escherichia coli / Q000235:genetics; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D012336:RNA, Ribosomal, 16S