Effects of Zn2+ and Cu2+ on growth, lignin degradation and ligninolytic enzymes in Phanerochaete chrysosporium

The influence of Zn2+ (6.0 x 10(-3) -18.0 x 10(-3) muM) and Cu2+ (4 x 10(-4) -1.2 x 10(-4) muM) in the basal medium on mycelial growth (dry weight), activities of lignin peroxidase (Lip), manganese peroxidase (Mnp), solubilization, and mineralization ((CO2)-C-14 evolution) of lignin during a period of 3 weeks was studied in Phanerochaete chrysosporium strain MTCC-787. Highest mycelial growth was obtained at 0.6 muM Zn2+ and 0.4 muM Cu2+ levels. Enzyme activities were found to increase up to the highest levels of both the trace elements. However, Zn2+ had a relatively more stimulatory effect on Lip production and the reverse was true in case of Cu2+. [C-14]Lignin solubilization was also promoted by higher levels of both trace elements. Mineralization of [C-14]lignin was optimal at 6.0 muM Zn2+ and 1.2 muM Cu2+. The stimulatory effect of Zn2+ on Lip production was correlated with higher rates of [C-14]lignin mineralization.