Production and characterization of crude laccase from Irpex sp. JS7 that decolorizes synthetic and natural melanin

The JS7 strain, isolated from an old forest tree, produces extracellular enzymes that decolorize synthetic and natural melanin from human hair. Phylogenetic analysis based on the internal transcribed spacer (ITS) sequence indicated that JS7 belongs to the genus Irpex. The JS7 strain has laccase activity while it lacks manganese and lignin peroxidase activity, which suggests that the JS7 strain melanin decolorization activity originated from laccase. Laccase production from the Irpex sp. JS7 improved three-fold in the presence of veratryl alcohol, compared to without an inducer. The optimum pH and temperature for melanin decolorization were 7.5 and 40 °C, respectively. The crude enzyme half-life at 25 °C was about 100 days, and it had high storage stability. The melanin decolorization reaction rate by the crude enzyme conformed to typical enzyme kinetic principles. In the presence of syringaldehyde as a redox mediator, the melanin decolorization rate was 75% within 5 days, similar to the decolorization percentage obtained using the enzyme alone. Based on these results, the Irpex sp. JS7 enzyme is suitable for use in melanin decolorization by whitening agents in the cosmetics industry.