Multicopper oxidase enzymes from Chrysoporthe cubensis improve the saccharification yield of sugarcane bagasse

The genome of phytopathogenic fungus Chrysoporthe cubensis has distinct groups of multicopper oxidase (MCO) coding genes, including new laccases, that could have the potential for biotechnological applications. Here, the complete genomic arsenal of MCOs from C. cubensis was identified and characterized. Laccases were induced, purified from the fungal crude extract, and these enzymes' potential to improve the sugarcane bagasse saccharification was tested. In silico genomic analysis revealed 13 MCOs classified as fungal ferroxidases; ascomycete laccases; laccases/ferroxidases; fungal pigments MCOs, and ascorbate oxidases. The C. cubensis cultivation in different lignocellulosic biomass yielded enzymatic extracts more efficiently for sugarcane bagasse saccharification than commercial preparations. The higher laccase activity (4.88 U g-1) was detected in the crude extract of the fungus cultivated on wheat bran and orange peel (3:1), and MCOs with laccase activity were purified from this protein extract. Mass spectrometry using MALDI-TOF/TOF identified two MCOs with 53.4 kDa and 74 kDa. The mixture containing the purified laccases oxidized 91% of the phenolic compounds produced from the alkaline pretreatment of sugarcane bagasse and allowed the improved saccharification yields. These enzymes are promising for application in biomass hydrolysis, especially in the detoxification of phenolic compounds.