PREDICTION OF METAL CATION TOXICITY TO THE BIOLUMINESCENT FUNGUS GERRONEMA VIRIDILUCENS

摘要

A correlation between the physicochernical properties of mono- [Li(I), K(I), Na(I)] and divalent [Cd(II), Cu(II), Mn(II), Ni(II), Co(II), Zn(II), Mg(II), Ca(II)] metal cations and their toxicity (evaluated by the free ion median effective concentration, EC50_F) to the naturally bioluminescent fungus Gerronema viridilucens has been studied using the quantitative ion character-activity relationship (QICAR) approach. Among the 11 ionic parameters used in the current study, a univariate model based on the covalent index (X_(m~r)~2) proved to be the most adequate for prediction of fungal metal toxicity evaluated by the logarithm of free ion median effective concentration (log EC50_F): log EC50_F = 4.243 (±0.243) -1.268 (±0.125)·X_(m~r)~2 (adj-R~2 = 0.9113, Alkaike information criterion [AIC] = —60.42). Additional two- and three-variable models were also tested and proved less suitable to fit the experimental data. These results indicate that covalent bonding is a good indicator of metal inherent toxicity to bioluminescent fungi. Furthermore, the toxicity of additional metal ions [Ag(I), Cs(I), Sr(II), Ba(II), Fe(II), Hg(II), and Pb(II)] to G. viridilucens was predicted, and Pb was found to be the most toxic metal to this bioluminescent fungus (EC50_F): Pb(II) > Ag(I) > Hg(I) > Cd(II) > Cu(II) > Co(II) ≈ Ni(II) > Mn(II) > Fe(II) ≈ Zn(II) > Mg(II) ≈ Ba(II) ≈ Cs(I) > Li(I) > K(I) ≈ Na(I) ≈ Sr(II)> Ca(II).