Conjugation dynamics of self-transmissible and mobilisable plasmids intoE. coliO157:H7 onArabidopsis thalianarosettes

Abstract

AbstractMany antibiotic resistance genes present in human pathogenic bacteria are believed to originate from environmental bacteria and conjugation of antibiotic resistance conferring plasmids is considered to be one of the major reasons for the increasing prevalence of antibiotic resistances. A hotspot for plasmid-based horizontal gene transfer is the phyllosphere,i.e.the surfaces of aboveground plant parts. Bacteria in the phyllosphere might serve as intermediate hosts with transfer capability to human pathogenic bacteria. In this study, the exchange of mobilisable and self-transmissible plasmids via conjugation was evaluated. The conjugation from the laboratory strainE. coliS17-1, the model phyllosphere colonizerPantoea eucalypti299R, and the model pathogenE. coliO157:H7∆stxto the recipient strainE. coliO157:H7∷MRE1O3∆stxin the phyllosphere ofArabidopsis thalianawas determined. The results suggest that short-term occurrence of a competent donor is sufficient to fix plasmids in a recipient population ofE. coliO157:H7∷MRE1O3∆stx. The spread of self-transmissible plasmids was limited after initial steep increases of transconjugants that contributed up to 10% of the total recipient population. The here-presented data of plasmid transfer will be important for future modelling approaches to estimate environmental spread of antibiotic resistance in agricultural production environments.ImportanceThis study investigated the transfer of antibiotic resistance conferring plasmids to enteropathogenicE. colion plant leaf surfaces. The results indicate that plasmid transfer may be high within the first 24 hours after inoculation. Transconjugant populations are maintained and stable for a considerable time frame on plant leaves, but invasion of the plasmid to the recipient population is limited.