Direct addition of cultures of tester bacteria into semi-permeable membrane devices (SPMDs) as a modified procedure for preliminary detection of mutagenic pollution of the marine environment by use of microbiological mutagenicity assays

Mutagenic pollution of the natural environment, including marine waters, is a very serious ecological problem. However, since chemical mutagens usually occur and act at low concentrations, their detection and identification is technically difficult, laborious and time-consuming. Therefore, preliminary detection of mutagenic pollution is commonly based on biological mutagenicity assays. On the other hand, triolein-containing semi-permeable membrane devices (SPMDs) provide a method for concentration of hydrophobic organic contaminants, including a large fraction of the mutagens. Combinations of SPMDs with microbiological toxicity and mutagenicity assays have already been described, but only SPMD-derived extracts, prepared with various organic solvents, were tested in such a way to date. We found that the presence of these solvents could interfere with the Vibrio harveyi bioluminescence-based mutagenicity assay. Moreover, preparation of the extracts from SPMD takes usually at least 48 h. Here, we propose a modified procedure, based on direct addition of tester bacteria cultures into SPMD. We found that this procedure is significantly (at least two times) more rapid and several times more sensitive than that based on testing the extracts. This optimization is presented in this report. Moreover, we have performed preliminary studies on samples of marine waters. Positive results (i.e. detection of mutagenic activity) were obtained when test samples came from a region known to be highly contaminated by industrial pollution, while negative results were observed in the case of samples from a region supposed to be of low risk for mutagenic pollution.