Heavy metal-induced oxidative stress and alteration in secretory proteins in yeast isolates

Abstract

In the recent years, yeasts have evolved as potent bioremediative candidates for the detoxi cation of xenobiotic compounds found in the natural environment. Candida sp. are well studied apart from Saccharomyces in heavy metal detoxi cation mechanisms. In the current study, Candida parapsilosis strain ODBG2, Candida sp. strain BANG3 and Candida viswanathii strain ODBG4 were isolated from industrial e uents and contaminated ground water were studied for their metal tolerance. Among these three isolates, the metal tolerance was found to be more towards Lead (Pb 2mM), followed by Cadmium (Cd 1.5mM) and Chromium (Cr(VI), 1mM). On further exploring the involvement of primary defensive enzymes in these isolates exhibited towards metal tolerance, the anti-oxidative enzyme Superoxide dismutase (SOD) was found to be prominently high as 25% during rst 24h of metal-isolate interaction. In the Catalase (CAT) enzyme assay, it was observed that, the increased enzyme activity at 48h also triggered the activity of peroxidases (PO), which lead to the increase in reduced glutathione (GSH) in the organism by 0.87-1.9 folds, as a metal chelator and also as a second line of defensive molecule. The exoproteome pro le showed the early involvement (exponential growth phase) of secreted proteins (low molecular weight) of about ~40-45kDa under Cd and Pb stress (0.5mM). The exoproteome pro ling under heavy metal stress in Candida parapsilosis strain ODBG2 and Candida viswanathii strain ODBG4 is the rst report.