Synthetic dyes decolorization potential of agroindustrial waste-derived thermo-active laccase from Aspergillus species

Laccase has become a biocatalyst of interest in biotechnological and industrial sector due to the ability to degrade an array of natural and synthetic toxicants. Consequently, laccase producing fungus was isolated from a soil sample collected from crude oil contaminated site and identified. Laccase production was carried out using medium formulated with agro-wastes, and the produced laccase was partially purified and characterized. Synthetic dyes decolorization potential of the laccase was likewise evaluated. The fungal isolate coded as CSB01 displayed remarkable laccase activity on agar plate. Based on the internal transcribed spacer (ITS) sequence analysis, it was identified as Aspergillus sp. Omeje with GenBank accession number MT476025. Among the agro residues used in the fermentation process, the isolate yielded maximum laccase activity (336 +/- 11.31 U/L) when groundnut husk was utilized as carbon source. The time course study showed that Aspergillus sp. Omeje had optimal laccase activity of 920 +/- 33.94 U/L at day 9 of fermentation period. Additional, the purified laccase was optimal active at pH and temperature of 7.5 and 50 degrees C, respectively. The determined K-m and V-max values of the enzyme were 0.14 mM and 0.45 mu mol/min, respectively. Furthermore, the degree of synthetic dyes decolorization obtained ranged from 36 +/- 11.31% for Basic Violet 2 to 82 +/- 12.73% for Vat Blue 5. The findings of the study suggest that the fungal laccase may be useful for industrial and/or bioremediation processes.