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

The influence of Zn2+ (6.0 × 10−3 –18.0 × 10−3μM) and Cu2+ (4 × 10−4 –1.2 × 10−4μM) in the basal medium on mycelial growth (dry weight), activities of lignin peroxidase (Lip), manganese peroxidase (Mnp), solubilization, and mineralization (14CO2 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 μM Zn2+ and 0.4 μM 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+. [14C]Lignin solubilization was also promoted by higher levels of both trace elements. Mineralization of [14C]lignin was optimal at 6.0 μM Zn2+ and 1.2 μM Cu2+. The stimulatory effect of Zn2+ on Lip production was correlated with higher rates of [14C]lignin mineralization.