Tributyltin (TBT) biodegradation induces oxidative stress of Cunninghamella echinulata

Abstract

Tributyltin (TBT) is one of the most deleterious compounds introduced into natural environment by humans. The ability of Cunninghamella echinulata to degrade tributyltin (TBT) (5 mg l−1) as well as the effect of the xenobiotic on fungal amino acids composition and proteins profile were examined. C. echinulata removed 91% of the initial biocide concentration and formed less hazardous compounds dibutyltin (DBT) and monobutyltin (MBT). Moreover, the fungus produced a hydroxylated metabolite (TBTOH), in which the hydroxyl group was bound directly to the tin atom. Proteomics analysis showed that in the presence of TBT, the abundances of 22 protein bands were changed and the unique overexpressions of peroxiredoxin and nuclease enzymes were observed. Determination of free amino acids showed significant changes in the amounts of 19 from 23 detected metabolites. A parallel increase in the level of selected amino acids such as betaine, alanine, aminoisobutyrate or proline and peroxiredoxin enzyme in TBT-containing cultures revealed that TBT induced oxidative stress in the examined fungus.