Production and Partial Characterization of Laccase from Pleurotus Species

Abstract

Pleurotus species potential for production of laccase under best levels of physicochemical conditions was studied. The study was conducted at the National Agricultural Biotechnological Research Center, Holetta. Collection of fruiting bodies of fungi were based on their morphology and cultured on potato dextrose agar plate. Eucalyptus sawdust and bean straw mixture on equal quantity was used as a main growth substrate for fungi and after extraction a 0.2187 U/ml of laccase enzyme activity was observed. The stability and activity of laccase was estimated under different substrate conditions and concentrations. The optimum pH for laccase activity was 6.0 with an activity of 0.2453 U/ml and it nearly retains 71% of its initial activity at this pH level after 12 hrs incubations. Laccase activity showed an increase in activity towards 50°C with 0.2478 U/ml activity and above 40°C its stability declined sharply and only 32% of its initial activity remain at 60°C overnight. This indicated that crude laccase extract was more stable at lower temperature (laccase only lost 4 and 12% of its initial activity at 20 and 30°C, respectively when incubated overnight) and needed to be stored at low temperatures. There was a linear relation between laccase activity and its substrate concentration. The reciprocal of laccase activity 1/V in U/ml and substrate concentration (1/[S]) in mM was considered to calculate kinetic parameters like Km and Vmax values which was 0.922 U/ml and 4.14 mM, respectively.

Keywords: Pleurotus species, Bean straw, Eucalyptus sawdust, Laccase, Guaiacol.

DOI: 10.7176/JBAH/13-7-01

Publication date:May 31^st 2023