Influence of the cultivation conditions on ligninolytic enzyme production in Pleurotus pulmonarius

Abstract

The highest level of laccase activity (391 U/l), as well as significant Mn-oxidizing peroxidases production, were found in solid-state culture with grapevine sawdust as the carbon source. After purification of extracellular crude enzyme mixture of Pleurotus pulmonarius, grown in the medium with the best carbon source (grapevine sawdust), three peaks of laccase activity were noted. The results obtained by purification also showed that the levels of phenol red oxidation, in absence of external Mn2+, were higher than phenol red oxidation levels in presence of external Mn2+. The highest laccase activity was in the medium with grapevine sawdust, as carbon source, and NH4Cl at a nitrogen concentration of 30 mM (441 U/l). The best nitrogen source for Mn-oxidizing peroxidase production was NH4NO3 at nitrogen concentration of 30 mM. The highest laccase activity was found in the presence of 5 mM Cu2+, and 5 mM Mn2+, respectively. The absence of Cu2+ and Mn2+, as well as their presence at the concentration of 1 mM, led to the peaks of Mn-oxidizing peroxidases activities. Zn2+ and Fe2+ caused a decrease, and Se, in all investigated forms, an increase of laccase and peroxidases activities.