Enzyme Profiles of <i>Pleurotus</i> HK-37 During Mycelia Vegetative Growth and Fruiting on Solid Sisal Waste Fractions Supplemented with Cow Manure

Abstract

The utilization of agro-industrial residues to cultivate edible mushrooms is of great environmental importance. However, the use of lignocellulose as carbon source depends on the capacity of the mushroom to produce lignocellulolytic enzymes and to secrete them to the extracellular substrate. Thus, the profile of lignocellulolytic enzymes produced during different phases of cultivation of <i>Pleurotus</i> HK-37 on sisal waste fractions supplemented with cow dung manure was determined. Mushroom cultivation was performed in plastic bags using substrates formulated by mixing various proportions of sisal leaf residues and sisal boles and supplementing with cow dung manure on dry weight basis. A total of three hydrolytic (carboxymethyl cellulase, pectinase and xylanase) and two oxidative (laccase and lignin peroxidase) enzymes produced by <i>Pleurotus</i> HK-37 were analyzed. Among these enzymes assayed, laccase was found to be predominant and highly expressed. After 30 days of incubation, its activity was 158.75 ± 7.66 Ug^-1wet spent mushroom substrate (SMS) on 30% supplemented sisal leaf decortication residues: sisal boles (25:75) substrate formulation. The highest lignin peroxidase activity observed was 4.01 ± 1.12 Ug^-1wet SMS during full mycelia colonization on unsupplemented sisal leaf decortication residues: sisal boles (25:75) substrate formulation. Meanwhile, for the hydrolytic enzymes; the highest carboxymethyl cellulase activity (5.45 Ug-1wet SMS) was observed on unsupplemeted sisal leaf decortication residues: sisal boles (75:25) substrate formulation 50 days after of substrate inoculation, that of xylanase (3.73 ± 0.98 Ug^-1wet SMS) was found on 10% supplemented sisal leaf decortication residues: sisal boles (0:100) substrate formulation after 20 days and that of pectinase (8.28 ± 2.14 Ug^-1wet SMS) was observed 20 days after substrate inoculation on 30% supplemented sisal leaf decortication residues: sisal boles (100:0) substrate formulation. The present investigation indicates the utilization of solid sisal wastes as support-substrate for production of both edible mushrooms and extracellular enzymes during solid state fermentation; it also provides an alternative approach and value-addition to these agrowaste residues.