Recovery of Lignocellulolytic Enzymes and Valorization of Spent Mushroom Substrate

Abstract

Spent Mushroom Substrate (SMS) comprises sugarcane bagasse, coconut coir, chicken manure, and paddy straw; inoculated with and farmed for Agaricus bisporus. At present, the waste generation at a mushroom cultivation plant in Goa is 40 tons/day (15,000 tons annually). Valorization of this waste has been explored in terms of extracting lignocellulolytic enzymes and briquette production. SMS was screened for the presence of lignocellulolytic enzymes and then was used to make briquettes. The enzymes found in SMS were cellulase and laccase, which were further concentrated via tangential flow filtration (TFF). Enzyme activity for Cellulase increased by four-fold (from 255.34±1.30 U/mL increased to 1022.21±4.84 U/mL) and Laccase increased by three-fold (from 4.83±0.02 U/mL to 13.21±0.05 U/mL). The concentrated enzyme cocktail was used to decolorize congo red dye. After only eight hours of enzymatic treatment at pH 4.8 on congo red, approx. 40-49% decolorization was accomplished. The color removal was due to the presence of the laccase enzyme. After enzyme extraction, all the residual SMS was utilized to generate briquettes with an initial reduction in its moisture content from 50% to 10%. The resulting briquette gave a Gross Calorific Value of 4,143 Kcal/kg with 12.60% ash content. Thus, SMS proves to be a valuable source for recovering enzymes and a cost-effective material for briquette production rather than going into landfills.

Keywords

• spent mushroom substrate
• lignocellulolytic enzymes
• laccase
• cellulase
• dye decolorization
• briquette