Lignocellulolytic enzyme production by Grifola frondosa (maitake) during solid state fermentation on two formulations based on coffee spent-ground and oak-sawdust

CARLOS ORREGO; SANDRA MONTOYA BARRETO; LAURA LEVIN

Clear Water Beach, Florida

Simposio; 32nd Symposium on Biotechnology for Fuels and Chemicals; 2010

To date, there are no studies dealing with the production of extracellular enzymes associated with substrate degradation for fungal nutrition in G. frondosa. In this work, growth and lignocellulolytic enzyme production along 107 days during solid state fermentation on two formulations based on industrial by-products: coffee spent-ground and oak-sawdust, was characterized. G. frondosa showed the capacity to degrade both substrates (oak-sawdust plus corn bran, and oak/corn bran supplemented with coffee spent-ground) causing a decrease of 67 and 50% in lignin content, and of 44 and 37% in polysaccharides (hemicellulose and cellulose) respectively. Coffee spent-ground was a good substrate for mycelial growth, but not for mushroom production, 35.3% biological efficiency was obtained when using oak sawdust plus corn bran as substrate. Cellulolytic, xylanolytic and ligninolytic activities were detected in the extracts recovered from the solid-state cultures. Enzyme activities peaked during colonization but declined drastically during fruiting body formation. Highest activities achieved were: endoglucanase 12.3, exoglucanase 16.2, B-glucosidase 2.3, endoxylanase 20.3, laccase 14.8 and Mn-peroxidase 7.4 U/g dry substrate. Although G. frondosa tested positive for Azure B plate degradation, a qualitative assay for lignin peroxidase, attempts to detect this activity during solid state fermentation were unsuccessful. Coffee addition not only decreased G. frondosa growth, but also xylanase and cellulase production. Caffeine, tannins, polyphenols or even high Zn concentrations could inhibit its growth, affect enzyme production and reproduction.