Enhancement of laccase production and malachite green decolorization by co-culturing Ganoderma lucidum and Trametes versicolor in solid-state fermentation

Abstract

Optimization of laccase production in white-rot fungi has been extensively studied. Metallic and aromatic compounds have been found to enhance enzyme production, but the development of bioremediation as an application field of this enzyme requires clean technologies. In this work, co-cultivation of Ganoderma lucidum and Trametes versicolor was performed, showing remarkable enhancement of laccase activity. Dual cultures were assayed for malachite green degradation (MG) in solid state fermentation (SSF) using a sawdust-based medium. The time for achieving complete decolorization of MG in co-cultivation was markedly shorter than that observed in monocultures. Dual-species treatment did not differ in wood dry weight loss and lignin, cellulose and hemicellulose degradation, compared to monocultures; but the selectivity index (lignin loss/cellulose loss) of dual cultures was markedly higher than those attained by monocultures. Moreover, a modified isoenzymatic laccase pattern was observed, showing one isoenzyme that was absent in monocultures. Dual cultures were able to decolorize and detoxify the dye more efficiently than the monocultures. The noticeable increase in laccase activity along with the more efficient decolorization and detoxification of MG by co-cultures of G. lucidum and T. versicolor in SSF makes this system a viable strategy for large scale application of white-rot cultures in bioremediation.