Novel laccase-like multicopper oxidases from the fungus Myrothecium roridum - production enhancement, identification and application in dyes removal

The aim of this study was to overproduce, identify and apply novel laccase-like multicopper oxidases (LMCOs) from Myrothecium roridum in a dye removal process. LMCOs' production was enhanced by modifying the medium and adding copper ions. After purification, two proteins, LMCO1 and LMCO2, with molecular masses of 46.7 and 66.3 kDa were discovered. Peptide analysis by mass spectrometry revealed that they belong to the cupredoxin superfamily. Characteristic peptide sequences were obtained for MCOs and bilirubin oxidases. Crude enzymes were applied in a dye decolorization process. Supplementation with 1 mM of vanillin allowed an almost complete elimination of the Indigo carmine within 3 hours. The dye was removed from a solution containing metals, surfactants and organic solvents. The in-gel assessment of the activity and decolorization ability of MCOs, followed by protein extraction and SDS-PAGE, confirmed that only LMCO2 was responsible for the dye removal. MCOs produced by Myrothecium sp. have been poorly studied before. The obtained results broaden knowledge on this subject and may contribute to the development of an eco-friendly method of dye elimination.