Spent mushroom compost as substrate for the production of industrially important hydrolytic enzymes by fungi Trichoderma spp. and Aspergillus niger in solid state fermentation

Abstract

Mushroom production is the biggest solid state fermentation industry in the world. Disposal and storage of spent mushroom compost (SMC) that remains after mushroom harvest poses a big economic and environmental problem. Production of industrially important hydrolytic enzymes by fungi on various agro-industrial wastes is a significant, open chapter in biotechnology. This paper proposes a novel application of SMC as substrate for cultivation of fungi in solid state fermentation (SSF) in order to obtain the enzymes cellulase, xylanase, amylase and beta-glucosidase. SMC can be used as a good substrate for cultivation of Trichoderma and Aspergillus without the addition of supplementary (nutritive) elements. Starting amount of SMC was reduced by 30% due to hydrolysis by a complex of cellulolytic enzymes. Material that is left behind is a more suitable fertilizer for horticulture. One fungal isolate was pointed out as a promising producer (Trichoderma atroviride isolate T42). It produced the greatest amount of total protein (0.204 mg mL(-1)), five isoforms of beta-glucosidase and the highest level (12 isoforms) of both endocellulase (0.76 U mL(-1)) and xylanase (2.31 U mL(-1)). The capacity of T42 to produce all examined enzymes in such a high number of isoforms demonstrates successful adaptation to new substrates.