Microbial ecotoxicity and mutagenicity of 1-hydroxypyrene and its photoproducts

1-Hydroxypyrene (1-HP) is a carcinogenic and slightly water-soluble polycyc lic aromatic hydrocarbon. Ecotoxicity and mutagenicity of 1-HP and its phot oproducts, and the effect of Mn2+ and Cu2+ on their mutagenicity were measu red with microbial assay in this study. The assay includes spread plate cou nting, direct counting, microbial mineralization of C-14-UL-D-glucose and M utatox (R) Test. At the concentration examined (0.8 muM), the photoproducts (after 1.5 h solar irradiation) of 1-HP inhibited microbial glucose minera lization activity (by 64%) after microbial assemblages of a local reservoir site were exposed for 1 day. However, heterotrophic bacteria were able to utilize 1-HP photoproducts as the growth substrates and increase viability counts by up to 4.75-folds. 1-HP exhibited positive response to Mutatox Tes t in both direct medium and S-9 medium, with the lowest observable effectiv e concentration of 0.625 muM in the test with direct medium. After photolys is, 1-HP decreased its mutagenicity. Mn 21 (312.5 muM-5 mM) and Cu2+ (6.25- 100 VM) themselves are not mutagenic. However, addition of the metal ions b efore or after photolysis modifies the light readings of 1-HP during the te st. Therefore, presence of metal ions could affect the genotoxicity of 1-HP in aquatic environments, depending on timing of the addition. (C) 2001 Els evier Science Ltd. All rights reserved.