Biotransformation of Aromatic Methyl Groups to Aldehyde Groups Using Laccase of Gloephyllum Stratum MTCC-1117

Laccases has been produced by white rot fungi are involved in lignin containing natural substrates wheat-straw, bagasse, saw-dust, corn cob and coir dust particle on the production of laccase enzyme in the aqueous cultivation medium of Gloephyllum stratum MTCC1117. The approach involved concentration of aqueous filtrate by ultrafiltration and anion exchange chromatography on DEAE (diethyl aminoethyl cellulose). From SDS-PAGE analysis the molecular mass of the purified enzyme is 57 kDa. The Km and kcat values of the laccase are found to be 18 μM and 0.34 s-1 using 2,6-dimethoxyphenol as the substrate, giving a kcat/Km value is 1.70 x 103 M-1 s-1. The pH and temperature optimum were 4.5 and 40 °C respectively. The purified enzyme has yellow colour and does not show absorption band around 610 nm found in blue laccases. Moreover the conversion of methylbenzene to benzaldehyde in the lack of mediator molecules, property exhibited by yellow laccases.