Influence of incubation temperature on activity of ligninolytic enzymes in sterile soil by Pleurotus sp. and Dichomitus squalens.

Solid state straw cultures of the white rot fungi Pleurotus sp. and Dichomitus squalens covered with a layer of sterile soil were incubated at 20 °C, 25 °C, 30 °C, and 34 °C. The activities of the extracellular enzymes laccase and manganese peroxidase (MnP) in the soil layers were measured over eight weeks. Pleurotus sp. produced high enzyme activity at low temperatures. Laccase was maximum at 25—30 °C and manganese peroxidase at 20 °C. D. squalens showed uniformly high levels of manganese peroxidase at 20—30 °C whereas at 34 °C, MnP was low and laccase showed an atypical time pattern. The discrepancy between low activity of the main enzyme, MnP, and high straw decomposition at 34 °C by D. squalens warrants further investigation of the enzyme inventory produced at that temperature.