Effect of tributyltin on Escherichia coli: role of modifying factors

The effects of inorganic and organic tin compounds and various factors affecting the toxicity of the latter to Escherichia coli were studied. In comparison to stannous chloride, tributyltin chloride (TBTC) was more inhibitory to the growth of the test organism; this may be due to its greater liposolubility and ready absorption through the bacterial membrane. The toxicity of TBTC to E. coli was modulated by various factors, such as pH, sulfate and chloride ions, and the presence of glucose, succinate, and reducing agents like cysteine and dithiothreitol (DTT). TBTC was more toxic to cells in minimal than in complex media. Similarly, this compound was more inhibitory to the growth of E. coli at acid pH than at basic pH. Succinate in contrast to glucose, when used as a carbon source, made the bacterium more sensitive to TBTC. Cysteine and DTT (both at a final concentration of 0.5 mM) partially protected the cells against the inhibitory effect of this agent.