Degradation of tributyltin by a bacterial strain isolated from polluted river water

Organotins loaded into the aquatic environment are generally degraded by bacteria in water and sediment. Though the aspects of microbial degradation have been studied under a mixed culture condition, little is known about the degradation in a pure culture condition, and there is no report on the isolation of organotin-degrading bacteria. In this paper, tributyltin (TBT)-degrading bacteria (no. 4 strain) were isolated from polluted river water in Osaka City. This bacterial strain degraded TBT within 24 h when the initial water concentration was 4–20 μg Sn/liter, and the addition of organic nutrient broth promoted the degradative ability. Following TBT degradation, dibutyltin (DBT) and monobutyltin (MBT) were produced, and finally MBT transformed into inorganic tin. The growth of the no. 4 strain was inhibited by the addition of TBT of more than 20 μg Sn/liter in the medium and, consequently, TBT degradation might have been suppressed with the elapse of time.