Kinetic studies and bioremediation potential of chromate reductase-characterized Aspergillus flavus from tannery effluent

Abstract

Chromium is among the major environmental pollutants endangering the health of all living things, including humans. Conventional methods for chromium detoxification are expensive, so bioremediation using fungi as potential agents for the detoxification of chromium is justified. This study aims to investigate chromium-resistant fungi capable of reducing or transforming Cr (VI) to less toxic Cr (III) from tannery effluents. The fungi were isolated from tannery wastewater and identified using 16S rRNA gene sequencing. Chromate reductase was isolated from pure fungal isolate and purified using molecular weight estimation and gel filtration chromatography. Aspergillus flavus, in an interesting turn of events, demonstrated 97% chromate reduction. The chromate reductase from Aspergillus flavus has K_M of 0.015 mM and a Vmax of 0.25 mol/min. Furthermore, the enzyme's activity was constant at its peak at pH 7.0 and 50 ^oC, with a single band displaying a molecular weight of 44 kDa for a pure protein. The data suggest that A. flavus can be a good candidate for the detoxification of Cr (VI) in industrial effluents. The efficiency of which can be attributed to the action of chromate reductase in the A. flavus.