Enhanced Growth and Production of Laccase and Peroxidases by Pleurotus ostreatus in an Enriched Natural Medium in Submerged Fermentation

Pleurotus ostreatus is a wood-decaying fungus capable of producing key enzymes for lignin degradation. Laccase (Lcc), manganese peroxidase (MnP), lignin peroxidase (LiP), and unspecific peroxygenase (UnP) activities of P. ostreatus grown on a wheat straw infusion medium enriched with malt extract and yeast extract (SMY) were studied. Growth kinetics and enzymatic parameters were also determined. Glucose medium was used as a control. The specific growth rate of P. ostreatus in SMY (0.62 h⁻¹) was more than twice as high as that shown in the control (0.24 h⁻¹). This fungus produced 5-fold higher biomass (15.7 g/L) in SMY medium than in the control (3 g/L). Lcc, MnP, LiP and UnP activities were approximately 67-,19-,11-, and 17-fold greater in SMY (3106, 4082, 1564, and 1883 U/L, respectively) than in the control (46, 213, 143, and 112 U/L respectively). P. ostreatus constitutively produced all the studied enzymes; however, the presence of wheat straw infusion components (i.e. phenolic compounds) in SMY enhanced the enzymes production. This is believed to be the first study to examine UnP production by P. ostreatus in an enriched natural medium. UnPs have been reported as promising enzymes for degradation of hazardous pollutants; however, there is still little information about their production.