P15: Purification and some properties of thermostable laccase from Thermobifida fusca

Laccase is a member of the multi-copper oxidase family. To produce thermostable laccases for development of the enzymatic bioprocessing, we isolated a potent extracellular laccase-producing thermophilic actinomycete, Thermobifida fusca BCRC19214 from compost soils. After 36 h of fermentation by the T. fusca BCRC 19214 in the 5-L fermentor, the laccases activity accumulated in the fermentation broth were 4.96 U/ml. The thermostable laccase was purified 4.64-fold as measured by specific activity from crude culture filtrate by ultrafiltration concentration, Q-Sepharose FF and DEAE-Sepharose CL-6B column chromatography. The overall yield of the purified enzyme was 7.49%. The purified enzyme gave an apparent single protein band on an SDS-PAGE. The subunit size of purified enzyme as estimated by SDS-PAGE was found to be 24.7 kDa. The optimum pH and temperature for the purified enzyme were 8.0 and 60^oC, respectively. The newly purified laccase showed oxidation activities for 8 dye compounds such as aminophenols, diamines and phenols at pH 8.0.