Characterization of laccase isoenzymes from the white-rot fungus Ganoderma sp.En3 and synergistic action of isoenzymes for dye decolorization

BACKGROUNDLaccase is an important and valuable enzyme with great potential for biotechnological applications. Laccase is produced mainly by white-rot fungi and often secreted extracellularly as different isoenzymes. Although there have been some reports about the biochemical characteristics and dye decolorization capability of laccase isoenzymes, few studies have been performed to evaluate the synergistic action of different laccase isoenzymes for decolorizing different types of dyes. RESULTSThree laccase isoenzymes designated as Lac-2, Lac-3 and Lac-4 were purified from the white-rot fungus Ganoderma sp.En3. Lac-2 showed stronger pH stability and thermostability than other two isoenzymes. Lac-2 also had a stronger ability to tolerate metal ions and organic solvents compared with other two isoenzymes. Different laccase isoenzymes from Ganoderma sp.En3 had different and selective decolorization capability. The synergistic action of different laccase isoenzymes for the enzymatic decolorization of dyes was further evaluated. There existed a positive synergistic effect of different laccase isoenzymes on the decolorization capability. Combination of Lac-3 with other two isoenzymes Lac-2 or Lac-4 could efficiently promote the decolorization of azo dyes. CONCLUSIONThis research will contribute to the deep understanding of functions of different laccase isoenzymes and better application of laccase in the biodegradation of environmental pollutants. (c) 2014 Society of Chemical Industry]