Saccharification of cellulosic material with Trichoderma reesei and fermentation by Scheffersomyces stipitis for the bioethanol production

• Main Authors: Fu-Yu Huang, 黃復榆
• Other Authors: Hung-Der Jang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/f3hd85

碩士 === 元培科技大學 === 食品科學研究所 === 100 === To increase the hydrolytic efficiency of cellulosic material with microbial enzyme and optimization of the conditions of bioethanol production by Scheffersomyces stipitis (Pichia stipitis) in the cellulosic hydrolysate-based media. Firstly, glucose was used as the sole carbon source for ethanol fermentation in a 500 ml flask. The ethanol yields were 27.80 g/L and 26.24 g/L by S. stipitis BCRC 21775 and BCRC 21777, respectively, when the initial glucose concentrations in the batch culture were 60 g/l. The ethanol yields of the test strains have found no significant difference, but S. stipitis BCRC 21777 performed a high efficiency for xylose fermentation and shorter fermentation time than BCRC 21775 did in the glucose/xylose- based media. Therefore, S. stipitis BCRC 21777 was chose as the xylose-fermenting strain for bioethanol production. In addition, the cellulolytic activities and growth rate of the soil isolates No. 9282, Trichoderma reesei BCRC 31863 and T. reesei BCRC 32924 were compared in the Mandels-Reese medium. We found that both of T. reesei BCRC 31863 and T. reesei BCRC 32924 possessed high cellulolytic activities; moreover, glucose and xylsoe content in the cellulosic hydrolysate could be increased to 1.65 g/L and 0.59 g/L, respectively, after inoculation with T. reesei BCRC 31863. Therefore, T. reesei BCRC 31863 was selected as the strain for saccharification of cellulosic material. After corncob was pretreated by sulfuric acid and autoclaved, T. reesei BCRC 31863 was inoculated to increase the hydrolytic efficiency and then batch and fed-batch cultures of S. stipitis in the corncob hydrolysate-based media was studied. The yeast biomass, ethanol yields and ethanol conversion rate was 10.62 g/L, 35.49 g/L and 53.30%, respectively, in the batch cultures using the media containing 60 g/L glucose and 10 g/L xylose. Furthermore, the fed-batch cultures were performed using the media containing initial 60 g/L glucose and 10.38 g/L xylose. The yeast biomass, ethanol yields and ethanol conversion rate was 11.55 g/L, 48.18 g/L and 54.49 %, respectively. The ethanol yields and ethanol conversion rate of the fed-batch cultures in the corncob hydrolysate-based media were higher than those were in the batch cultures. However, the ethanol yields and ethanol conversion rate cultured in the fermentor were lower than those of the cultures in conical flask. Based on the results, scale-up of fed-batch fermentation, using corncob hydrolysate as the substrate, under the optimum conditions for the bioethanol production could be developed to make the process industrially feasible.