UC Riverside

Varying conditions in the environment can act as factors that influence the emergence and growth of antibiotic-resistant bacteria. To explore the effects of the environmental conditions on different antibiotic resistant mutants, we monitored the growth curves of the wild type and two strongly antibiotic resistant mutants and three mildly antibiotic resistant mutants of E.coli K-12 and conducted competition tests in pairs under different temperature, pH and salinity concentrations. Wild type was dominant at all experimental conditions, while adding antibiotic and pesticides selection stress reversed this overwhelming superiority only when we changed the incubation temperature at pH=7. The strongly resistant mutant gained more growth advantages as the temperature and pH increased and outcompeted the mildly resistant mutants. When we added additional selection pressure under experimental conditions, we found that the antibiotic and pesticide stress made this growth advantage of the strongly resistant mutant more obvious and further inhibited the growth of the wild type and mildly resistant mutants. These findings provide suggestions for the impact of environmental factors on the growth of various antibiotic resistant bacteria and the effective elimination of strong antibiotic resistant bacteria in certain conditions in the natural environment.