Digestibility of Betung Bamboo Fiber Following Fungal Pretreatment

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This research evaluated the effect of fungal pretre atment of betung bamboo fibers and enzymatic- and microwaveassisted hydrolysis on the reducing sugar yield. Th e enzymatic hydrolysis of the pretreated biomass wa s carried out with cellulase and 10 and 20 FPU/g of substrate in a shaking incubator at 50 °C and 150 rpm for 48 h. The sulfuric acid concentration used in the microwave-assisted acid h ydrolysis was 1.0, 2.5, and 5%, either with or with out the addition of activated carbon. Microwave irradiation (330 Wat t) was applied for 5‐12.5 min. The yield of reducin g sugar was better with the microwave-assisted acid hydrolysis, and the yield tended to increase with an increase in the irradiation time. Based on the dry weight of the initial biomas s (bamboo), pretreatment with 5% inoculum loading resulted in a higher reducing sugar yield (17.06%) than with 10% inoculum loading (14.54%). At a 1% acid concentration, the formation of brown compounds decreased, followed by a reduction in the reducing sugar yield. The addit ion of activated carbon at a 1% acid concentration seemed to be of no benefit with respect to the yield in th e microwaveassisted acid hydrolysis. The pretreatment with the 5% inoculum loading for 12.5 min at 1% acid concentration resulted in the highest reducing sugar yield. Under these co nditions, the yield was 6.3-fold that of the reduci ng sugar yield using 20 FPU/g of cellulase. The rate of bamboo hollocell ulose hydrolysis reached 22.75% of the maximum theoretical reducing sugar reducing sugar of dry biomass.