Utilization of Spent Sawdust Matrix after Cultivation of Grifola frondosa as Substrate for Ethanol Production by Simultaneous Saccharification and Fermentation

Disposal of spent sawdust matrix (SSM) after cultivation of Maitake mushroom (Grifola frondosa) has been very problematic. In order to establish a new method of utilization, the feasibility of using SSM as substrate for ethanol production in the simultaneous saccharification and fermentation process (SSF) was investigated. When the physicochemical properties of SSM were investigated, it was clear that SSM was decomposed by G. frondosa during cultivation. SSM was more susceptible to attack by cellulase than wood chips (WC). Dry milling followed by hot water treatment using an autoclave was suitable for the pre- treatment of SSM prior to saccharification. The maximum glucose yield of the pretreated SSM was approximately 88%, about 20 times the value for WC with the same pretreatment. When SSM was used as a substrate for SSF, the maximum ethanol concentration was approximately 16gl-1 (this value implies a theoretical ethanol yield of 0.75 [g-ethanol/g-total glucose in SSM]). Thus pretreated SSM could be a good source for ethanol production by SSF.