Susceptibility of bacterial populations to organotin compounds and microbial degradation of organotin compounds in environmental water

Abstract

Susceptibility of bacterial populations to organotin compounds was studied in river water. Organotin compounds including tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPT), diphenyltin (DPT) and monophenyltin (MPT) dissolved in dimethyl sulfoxide (DMSO) were added to river water. Number of colony forming units (CFU) of bacteria was measured using 1.5% agar plate. CFU count was not decreased at concentration less than 1.0 mg liter −1 of organotin compounds. CFU was decreased markedly at 10 mg litre −1 of TBT, DBT or MPT, however, the populations increased after 2 days. Degradation of TBT, DBT and TPT by bacteria in estuarine water was studied using river die-away method. TBT was degraded to DBT moderately, and DBT was degraded to MBT rapidly. When the initial concentration of TBT or DBT was adjusted to 9.3 and 8 μg liter −1, half-lives of TBT and DBT were 15 and 10 days, respectively. TPT was degraded scarcely during 60 days of culture. Growth of bacteria in estuarine waters containing organotin compounds was found throughout the study period.