Tributyltin Degradation in Estuarine Sediments and the Isolation of Tributyltin-Resistant Bacteria from These Sediments

Abstract

In order to determine what happens to organotin compounds in estuarine sediments and to develop clean-up technologies for these compounds, this study investigated biotic and abiotic degradation of tributyltin (TBT) in estuarine sediment slurries under aerobic and anaerobic conditions, both in daylight and in darkness. Following the TBT degradation in estuarine sediment slurries, we found that dibutyltin (DBT), monobutyltin (MBT), and inorganic tin (Sn) were produced simultaneously. The highest TBT degradation rates in sediment slurries (0.052-0.130 μM day^(-1)) were much higher than those in aseptic control sediment slurries 0.009-0.013 μM day^(-1)). Thus, the biotic process was the most significant mechanism for TBT degradation in these estuarine sediment slurries. It was found that TBT degraded faster under aerobic conditions (0.092-0.130 μM day^(-1)) than under anaerobic conditions (0.052-0.071 μM day^(-1)) in sediment slurries. There were no significant differences in the highest TBT degradation rates, either in daylight or in darkness, under both aerobic and anaerobic conditions. Twenty eight TBT-resistant bacterial strains were isolated in this study, with all of the isolates being Gram negative, rod-shaped bacteria. The 16S rRNA gene sequence analyses revealed that these isolates could be categorized into four groups, but that they were phylogenetically closely affiliated to γ-proteobacteria.