The improvement of sodium hydroxide pretreatment in bioethanol production from Japanese bamboo Phyllostachys edulis using the white rot fungus Phlebia sp. MG-60

Abstract

The concentration range of sodium hydroxide solution (0.0–7.0% w/w) was used to determine the impact of chemical pretreatment in bioethanol production from Japanese bamboo by using the white rot fungus Phlebia sp. MG-60. A pretreatment of sodium hydroxide at 120 °C for 1 h demonstrated a significant effect on the removal of lignin and xylan components, leading to an increase in glucan composition for the pretreated bamboo. The saccharification rate was improved from 41.0% in the initial sample to 89.5% in the 7.0% NaOH pretreated sample. This first report on consolidated bioprocessing of Japanese bamboo points out that the highest ethanol yield was 12.8% in 7.0% NaOH pretreated samples, equivalent to 28.5% of polysaccharide volume converted to ethanol, while the conversion proportion in the initial bamboo sample was negligible. Bioethanol production by applying semi-simultaneous saccharification and fermentation showed the highest conversion rate: 58.9% in 7.0% NaOH pretreated samples. However, after considering the weight loss of bamboo samples during pretreatment, the 1.0% NaOH pretreated sample was indicated as the highest ethanol-producing efficiency with 38.1% conversion rate. These results show that sodium hydroxide is an effective pretreatment in combination with Phlebia sp. MG-60 in bioethanol production from Japanese bamboo, with or without commercial hydrolytic enzymes.