Abstract

A lignolytic basidiomycete fungus, Funalia trogii (Berk.), was isolated from decayed wood in coastal Tanzania and cultivated in submerged culture. Initially screened crude enzyme filtrate showed complete rhemazol brilliant blue - R (RBBR) decolorization 2,2’-azino-bis (3-ethylbenzthiazoline)-6-sulfonate and guaiacol oxidation after 7 days of incubation. The fungal filtrate had maximum laccase activity of 593 U/ml after 15 days of incubation. A laccase was purified by anion exchange and size exclusion chromatography to good purity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). The isolated main component had a molecular weight of ca 58 kDa as determined by MS and an isoelectric point (pI) of 3.8. The optimal pH and temperature range for the purified laccase were 4.0 - 5.0 and 50 - 70 ºC, respectively, using 2, 6-dimethoxyphenol as a substrate.

Key words: Funalia trogii, laccase, anion exchange chromatography, size exclusion chromatography, electrophoresis, isoelectric focusing.