Triphenyltin biosorption, dephenylation pathway and cellular responses during triphenyltin biodegradation by Bacillus thuringiensis and tea saponin

Triphenyltin is an endocrine disruptor that has polluted the global environment, and thus far, information regarding the mechanisms of triphenyltin biodegradation and cellular metabolic responses is severely limited. The question of whether dephenylation during degradation occurs successively or synchronously is also not clear. Here, these processes were illuminated through experiments involving surfactant-enhanced biodegradation of triphenyltin and its metabolites by Bacillus thuringiensis. Tea saponin significantly enhanced phenyltin solubility, biosorption, membrane permeability, protein expression, cell density and Cl− and PO43− use, reduced intracellular Na+, NH4+, K+ and Mg2+ release, and accordingly increased phenylation biodegradation. Phenyltin biodegradation was initially triggered by benzene ring cleavage, which occurred individually and synchronously, producing diphenyltin, monophenyltin, and tin. After degradation by cells in the presence of 60 mg L−1 tea saponin for 7 d, residual concentrations of triphenyltin, diphenyltin, and monophenyltin were decreased to 283, 270, and 235 μg L−1, respectively.