Effect of -ray irradiation on enzymatic hydrolysis of spent corncob substrates from edible mushroom, enokitake() cultivation

Shimokawa, Tomoko*; Nakamura, Masaya*; Nagasawa, Naotsugu; Tamada, Masao; Ishihara, Mitsuro*

The effect of -ray irradiation on enzymatic hydrolysis of spent enokitake mushroom substrate containing corncob meal and rice bran as major components was studied. Almost all the lignin component remained in the bottle though 34% of the original substrate was consumed. Polysaccharides consisting of glucose and xylose residues were the major components of the spent substrate. The saccharification rate of the spent substrate doubled with irradiation at a dose of 500 kGy, and the irradiated sample formed finer particles than the untreated sample after the same period of grinding. The holocellulose was apparently depolymerized by irradiation, resulted in the fragility of the substrate. An appreciable amount of xylan-derived sugars were extracted with water from the irradiated sample. The enzymatic saccharification rate of the irradiated spent enokitake substrate increased to over 80% with Cellulosin TP 25 from Trichoderma viride, which possesses endo--D-xylanase and -D-xylosidase activities as well as cellulase activities.