Pretreatment and treatment of cellulosic agriculture wastes with Streptomyces spp. cellulase for the production of bioethanol

• Main Authors: Ming-Zhang Lai, 賴銘樟
• Other Authors: Hung-Der Jang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/u3v95f

碩士 === 元培科技大學 === 生物技術研究所 === 98 === Cellulosic biomass from agricultural wastes has been considered as an attractive route for ethanol production. However, cellulosic biomass for ethanol production needs pretreatments via liquefaction and saccharification. The aim of this research was to study the optimal conditions for reducing sugar production by acid/autoclaving pretreatment and hydrolysis of corncob material with Streptomyces culture, and the yields of ethanol from fermentation of cellulosic hydrolysate. After corncob was pretreated with 0.5% (v/v) sulfuric acid and autoclaved at 121℃ for 60 min, the cellulosic residue was then hydrolyzed by commercial cellulase, 0.9 g/g dried substrate of total reducing sugar was produced. However, the hydrolysates from autoclaving pretreated corncob material could be converted to maximal yields of reducing sugar when Streptomyces were cultured. Total reducing sugar concentration reached 5.3 g/g dried substrate after Streptomyces sp. was incubated. During the cultivation CMCase, Avicelase and β-glucosidase, were produced by the Streptomyces sp. T3-1, favored the conversion of cellulose to glucose. Cultures of Streptomyces sp. T3-1 at 37℃ greatly increased reducing sugar yields with the production of CMCase, Avicelase and β-glucosidase activity of 3.8, 3.9 and 3.8 IU/ml, respectively. The yields of reducing sugar and activities of CMCase, Avicelase and β-glucosidase of Streptomyces sp. incubated at 37℃ were higher than those of at 50℃. Further batch fermentation of cellulosic hydrolysate containing 1-4% glucose was performed using Saccharomyces cerevisiae BCRC 21812. The maximal yields of yeast biomass and ethanol were 14.6 and 24.2 g/L, respectively, and the conversion ratio of 0.60 g ethanol/g glucose was obtained from the batch fermentation of cellulosic hydrolysate containing 4% glucose. Besides, in the fed-batch fermentation using hydrolysate containing 2% glucose and supplementing 3% glucose after 1 d of fermentation, the yields of yeast biomass and ethanol were 44.8 and 32.9 g/L, respectively, and the conversion ratio of 0.66 g ethanol/g glucose. The research results are meaningful in fuel ethanol production from agricultural cellulosic wastes.