Heterologous expression and characterization of a dye-decolorizing peroxidase from Ganoderma lucidum, and its application in decolorization and detoxifization of different types of dyes.

ABSTRACT

Dye-decolorizing peroxidases (DyPs) belong to a novel superfamily of heme peroxidases that can oxidize recalcitrant compounds. In the current study, the GlDyP2 gene from Ganoderma lucidum was heterologously expressed in Escherichia coli, and the enzymatic properties of the recombinant GlDyP2 protein were investigated. The GlDyP2 protein could oxidize not only the typical peroxidase substrate ABTS but also two lignin substrates, namely guaiacol and 2,6-dimethoxy phenol (DMP). For the ABTS substrate, the optimum pH and temperature of GlDyP2 were 4.0 and 35 °C, respectively. The pH stability and thermal stability of GlDyP2 were also measured; the results showed that GlDyP2 could function normally in the acidic environment, with a T50 value of 51 °C. Moreover, compared to untreated controls, the activity of GlDyP2 was inhibited by 1.60 mM of Mg2+, Ni2+, Mn2+, and ethanol; 0.16 mM of Cu2+, Zn2+, methanol, isopropyl alcohol, and Na2EDTA·2H2O; and 0.016 mM of Fe2+ and SDS. The kinetic constants of recombinant GlDyP2 for oxidizing ABTS, Reactive Blue 19, guaiacol, and DMP were determined; the results showed that the recombination GlDyP2 exhibited the strongest affinity and the most remarkable catalytic efficiency towards guaiacol in the selected substrates. GlDyP2 also exhibited decolorization and detoxification capabilities towards several dyes, including Reactive Blue 19, Reactive Brilliant Blue X-BR, Reactive Black 5, Methyl Orange, Trypan Blue, and Malachite Green. In conclusion, GlDyP2 has good application potential for treating dye wastewater.