Sub-inhibitory concentrations of kanamycin fix fusA mutation in an environmental Pseudomonas sp.

Antibiotics can disseminate into the environment and persist at sub-inhibitory concentrations. It is not known what effect such low levels of pollution might have on environmental organisms. Here we have shown that environmental levels of antibiotics can rapidly fix a mutation in an environmental bacterium which correlates with a four-fold increase in antibiotic resistance. This shows that selection can be driven by low concentrations of antibiotics and suggests that similar selection events could be occurring at a high frequency in all environmental bacteria, disrupting normal microbial processes and contributing to the global problem of antibiotic resistance.