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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.

A laccase-producing ascomycete fungus was isolated from soil collected around the premises of a textile dye factory and identified as Nectriella pironii. Efficient laccase production was achieved via the synergistic action of 1 mM copper sulfate and ferulic acid. Extracts of rapeseed oil cake, grass hay, and leaf litter collected in a pocket urban park were used for enzyme production. The highest laccase activity (3,330 U/L) was observed in the culture grown on the leaf litter extract. This is the first report on biosynthesis of laccase by N. pironii. This is also the first study on utilization of naturally fallen park leaves as a substrate for fungal laccase production. The extracellular enzyme possessing laccase activity was purified to homogeneity by ion-exchange and gel filtration chromatographic techniques. The amino acid sequence of the protein revealed highest similarity to the laccase enzyme produced by Stachybotrys chartarum-and considerable homology to those produced by other fungal species. The purified laccase possessed a molecular mass of 50 kDa. The enzyme had an optimum pH of 2.0 or 6.0 and retained more than 50% of residual activity after 3 hours of incubation at pH 3.0-10.6 or 4.0-9.0 when 2,2 0-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid or 2,6-dimethoxyphenol, respectively, were used. Dithiothreitol, β-mercaptoethanol, and sodium azide at 1 mM concentration strongly inhibited the laccase activity, while in the presence of 50 mM urea, the enzyme was found to retain 25% of its activity. The laccase was able to decolorize more than 80% of Indigo Carmine, Remazol Brilliant Blue R, Reactive Orange 16, and Acid Red 27 dyes within 1 h. The possibility of leaf litter use for the production of the laccase enzyme from N. pironii (IM 6443), exhibiting high pH stability and degradative potential, makes it a promising tool for use in different environmental and industrial operations.