Toxicity of butyltin, phenyltin and inorganic tin compounds to sulfate-reducing bacteria isolated from anoxic marine sediments

The toxicity of butyltin, phenyltin and inorganic tin compounds to three pu re strains of sulfate-reducing bacteria (SRB), isolated from a tributyltin (TBT)-polluted sediment, was determined. The isolated strains were identifi ed as belonging to the genus Desulfovibrio. A new toxicological index (GR(2 5)) was developed to assay the toxicity of organotin compounds, Deleterious effects on suspended anaerobic cell cultures were observed for concentrati ons ranging between 500 and 600 mu M for tin tetrachloride, 55 and 260 mu M for triorganotins, 30 and 90 mu M for diorganotins, and 1 and 6 mu M for m ono-organotins, Whereas the number of substituents influenced the toxicity of organotins, the type of substituent (butyl or phenyl) proved to have lit tle or no impact. Trisubstituted compounds (tributyl- and triphenyl-tin) we re less toxic to these strains of SRB than the monosubstituted forms (monob utyl- and monophenyl-tin), This is the opposite trend to that currently rep orted for aerobic organisms. Under the given anoxic conditions, the toxicit y of organotin compounds obtained yielded a significant negative correlatio n with the total surface area (TSA) of the tested molecules. Comparison of the TBT toxicity data observed for different microbial groups suggests that the tolerance of bacteria to organotin compounds might be related to organ otin-cell wall interactions as well as to aerobic or anaerobic metabolise p athways. Copyright (C) 2000 John Wiley & Sons, Ltd.