The synergism of manganese peroxidase and laccase from Cerrena unicolor BBP6 in denim dye decolorization and the construction of gene co-expression system in Pichia pastoris

Abstract

Extracellular ligninolytic enzymes of white-rot fungi including laccase and manganese peroxidase (MnP), are being applied to denim bleaching process due to their superior degradation capability of synthetic dyes. In the process of denim bleaching by the extracellular broth of Cerrena unicolor BBP6, MnP was primarily responsible for the decolorization, while laccase played an assisting role in the decolorizing reaction by participating in the production of H2O2 to initiate the catalytic reaction of MnP. In our case, the concentration of H2O2 (50 μM) generated from the oxidation reaction of Mn2+ by laccase (2869 U L−1), guaranteed that 200 U L−1 of MnP could carry out its significant decolorization ability of denims without exogenous H2O2 in the bleaching system. A gene co-expression system of Pichia pastoris was then constructed with the highest recombinant MnP and laccase activity of (178.8 and 6390.6, U L−1), respectively. The recombinant enzyme broth on day 6 containing the highest MnP activity and appropriate concentration of H2O2 showed a significantly enhanced decolorization effect on denims. Our results demonstrated that the recombinant enzyme complex (rMnP3-BBP6 and rLaccaseA-189) has shown promising application potential in textile industries, especially in denim bleaching process.