Phylogenetic distribution of traits associated with plant colonization in Escherichia coli

Abstract

Plants are increasingly considered as secondary reservoirs for commensal and pathogenic Escherichia coli strains, but the ecological and functional factors involved in this association are not clear. To address this question, we undertook a comparative approach combining phenotypic and phylogenetic analyses of E. coli isolates from crops and mammalian hosts. Phenotypic profiling revealed significant differences according to the source of isolation. Notably, isolates from plants displayed higher biofilm and extracellular matrix production and higher frequency of utilization of sucrose and the aromatic compound p-hydroxyphenylacetic acid. However, when compared with mammalian-associated strains, they reached lower growth yields on many C-sources commonly used by E. coli. Strikingly, we observed a strong association between phenotypes and E. coli phylogenetic groups. Strains belonging to phylogroup B1 were more likely to harbour traits indicative of a higher ability to colonize plants, whereas phylogroup A and B2 isolates displayed phenotypes linked to an animal-associated lifestyle. This work provides clear indications that E. coli phylogroups are specifically affected by niche-specific selective pressures, and provides an explanation on why E. coli population structures vary in natural environments, implying that different lineages in E. coli have substantially different transmission ecology.

Microbiological Survey of Locally Grown Lettuce Sold at Farmers' Markets in Vancouver, British Columbia

“…Generally, commensal enteric strains belong to phylogenetic groups A and B l, whereas extraintestinal pathogenic strains are placed into group B2 and, to a lesser extent, group D (10,20,21,40). Our findings are consistent with those of Meric et al (31), who recently reported a higher prevalence of Bl isolates on plants than isolates of other phylogenetic groups. B l strains have been recovered from a wide variety of sources (e.g., humans, livestock, natural environments), and thus they are considered to be host generalists (6,48).…”

Evidence for Coexistence of Distinct Escherichia coli Populations in Various Aquatic Environments and Their Survival in Estuary Water

“…These results were consistent with recent studies showing that E. coli B1 strains can persist longer in water than strains of the other phylogroups (13,14). The prevalence of B1 isolates has also been observed in other environmental samples, such as manure and drinking water, or associated with plant colonization (see the reference list in reference 43).…”

“…Thus, the ability to utilize sucrose could provide a substantial advantage in the environment (43,45). However, in this study, no relationship between carbon degradation and the survival ability of isolates was observed.…”

“…A strong association between phenotypes and E. coli phylogenetic groups was observed for E. coli isolated from plants, with B1 isolates more likely harboring traits indicative of a higher ability to colonize plants, such as higher biofilm formation and higher frequency of utilization of sucrose and an aromatic compound (43). Thus, the ability to utilize sucrose could provide a substantial advantage in the environment (43,45).…”

Type III Secretion System and Virulence Markers Highlight Similarities and Differences between Human- and Plant-Associated Pseudomonads Related to Pseudomonas fluorescens and P. putida

“…Thus, the plant rhizosphere, already known for its ability to host populations known to be human pathogenic and belonging to P. aeruginosa (75,76), Burkholderia spp. (77,78), or Escherichia coli (79), could also be a potential source of P. fluorescens opportunistic pathogens. The possible involvement of Hrp1 family secretion systems in the virulence of respiratory tract isolates toward animal cells is supported by the altered virulence of a mutant of the respiratory tract isolate P. fluorescens MFN1032 (syn.…”