Ligninolytic enzyme activities alternate with mushroom production during industrial cultivation of Pleurotus ostreatus on wheatstraw-based substrate

Two commercial Pleurotus ostreatus strains (030 and K12) were cultivated under industrial conditions on wheat straw blocks 1718 kg in weight. Within 10 weeks of cultivation, three flushes of fruiting body production were obtained with total yields of 4.2 and 4.1 kg mushrooms/substrate block and a biological efficiency (BE = total yield of fresh mushrooms per dry weight of substrate) of about 95%, respectively. Ligninolytic activities were followed up within the substrate over the cultivation periods. Laccase, manganese peroxidase (MnP) and versatile (manganese-independent) peroxidase (VP) activities were high in vegetative growth phases within the substrate and dropped upon initiation of fruiting body formation to be hardly detectable at the harvest of the mature mushrooms. Directly after harvest at all observed flushes, there was a sharp increase in all three enzymatic activities in the substrate for both strains (maximum activities for laccase 1.1–1.3 U/ml, for MnP 15–16 U/ml and for VP 1.1–1.4 U/ml). Enzymes can be extracted by pressing the spent mushroom substrates (SMS). Potential applications for the press juice or the enzymes in the SMS are discussed.