Mycelial growth and production of laccase and peroxidases by Pleurotus ostreatus and Agrocybe aegerita in liquid fermentation

Mycelial growth of Pleurotus ostreatus and Agrocybe aegerita in malt extract broth was evaluated. Laccase, manganese peroxidase (MnP), lignin peroxidase (LiP) and unspecific peroxygenase (UnP) activities were determined in both strains, using biochemical and polyacrylamide gel electrophoresis techniques. No strain showed MnP, LiP, and UnP activities. P. ostreatus had higher biomass production and laccase yield values than those shown by A. aegerita. P. ostreatus produced approximately twice as much biomass (Xmax) compared to A. aegerita (9.12 and 5.27 g/L, respectively). Maximum laccase activity (Emax) was nine-fold higher in P. ostreatus than in A. aegerita (106.5 and 12.23 U/L, respectively). P. ostreatus and A. aegerita showed 3 bands (estimated to be approximately 42, 55, 85 and 212 kDa) and one band (estimated to be approximately 35.2 kDa) with laccase activity, respectively. These results show that laccases are constitutively produced in both fungal species, whereas MnP, LiP and UnP are inducible enzymes. P. ostreatus has a great potential in the biotechnological production of laccases.