UCLA

Exposure to both antibiotics and changes in temperature can induce similar physiological responses in bacteria. Thus, changes in growth temperature could affect resistance to antibiotics. Previous studies have found that evolution under antibiotic stress causes shifts in optimal growth temperature of bacteria, but little is known if evolution under thermal stress affects antibiotic resistance. Examining 114 heat-adapted strains, we asked if evolution under thermal stress affects optimal growth temperature, if there are any correlations between heat adaptation and antibiotic resistance, and if antibiotic efficacy for these strains change depending on the local environment’s temperature. We found that: (1) most of the heat-adapted strains displayed a decrease in optimal growth temperature relative to the ancestor strain, (2) there were complex patterns of changes in antibiotic resistance when comparing the heat-adapted strains to the ancestor strain, and (3) there were no significant correlations between antibiotic resistance and changes in optimal growth temperature.