Vulnerability of natural bacterial communities to antibiotics in aquatic environments and its impact on biogeochemical cycles
Antibiotics discharged into the environment are likely to affect the growth and metabolism of naturally occurring bacteria that are different from the original "target" bacteria. Furthermore, it is expected that the functions that bacteria play in the circulation of materials in ecosystems, such as the decomposition of organic matter and the associated regeneration of nutrients, will also be affected. In this study, we aimed to clarify the effects of antibiotics on bacterial communities inhabiting rivers and lakes through culture experiments. Water samples collected from Japanese rivers and lakes were cultured after adding various concentrations of an antibiotic (tetracycline). Susceptibility to antibiotics varied by phylogenetic group (classification at the phylum, class, and order levels). Furthermore, the trends were similar between river and lake samples. Discharge of high concentrations of antibiotics into natural waters may affect biogeochemical processes, such as the decomposition of organic matter, through changes in bacterial community composition.