Modulation of cadmium tolerance and lignocellulosic enzyme function in <em>Aspergillus terreus</em> exposed to ionizing radiation

Abstract

Heavy metal pollution is an alarming problem for the ecosystem. Cadmium (Cd) is one of the most common heavy metal contaminants in the environment. In recent years different abatement strategies are being implemented to control metal pollutants. Amongst these, bioremediation has gained considerable focus because it is a cost-effective, eco-friendly and self-sustainable process. Our present work describes the potential of gamma irradiation to enhance heavy metal tolerance in <em>Aspergillus terreus</em>. Gamma exposed<em> A. terreus</em> could tolerate upto 150 ppm of Cd in the medium, while the unirradiated ones tolerated only upto 90 ppm of Cd. Gamma exposed (20-100 Gy) <em>A. terreus</em> have manifested significantly higher efficiency to uptake Cd and subsequent removal from liquid broth when grown in medium stressed with Cd as compared to the unirradiated counterparts<strong>. </strong>Potential of gamma irradiation has been reflected also in stimulating CMCase and &alpha;-amylase activity of <em>A. terreus</em> grown under Cd stress. An absorbed dose of 100 Gy resulted 58.87% more CMCase and 1.09-fold more &alpha;-amylase activity of <em>A. terreus</em> when grown in medium containing 90 ppm of Cd. The study highlights the possibility of utilizing gamma irradiation in approaching microbe-mediated Cd bioremediation in addition to cellulosic bio-waste or polymer degradation.