Lo Yung-Chung, Su Yi-Chen, Chen Chun-Yen, Chen Wen-Ming, Lee Kuo-Shing, Chang Jo-Shu
Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Bioresour Technol. 2009 Dec;100(23):5802-7. doi: 10.1016/j.biortech.2009.06.066. Epub 2009 Jul 14.
A "temperature-shift" strategy was developed to improve reducing sugar production from bacterial hydrolysis of cellulosic materials. In this strategy, production of cellulolytic enzymes with Cellulomonas uda E3-01 was promoted at a preferable temperature (35 degrees C), while more efficient enzymatic cellulose hydrolysis was achieved under an elevated culture temperature (45 degrees C), at which cell growth was inhibited to avoid consumption of reducing sugar. This temperature-shift strategy was shown to markedly increase the reducing sugar (especially, monosaccharide and disaccharide) concentration in the hydrolysate while hydrolyzing pure (carboxymethyl-cellulose, xylan, avicel and cellobiose) and natural (rice husk, rice straw, bagasse and Napier-grass) cellulosic materials. The cellulosic hydrolysates from CMC and xylan were successfully converted to H(2) via dark fermentation with Clostridium butyricum CGS5, attaining a maximum hydrogen yield of 4.79 mmol H(2)/g reducing sugar.
为了提高纤维素材料细菌水解产生的还原糖产量，开发了一种“温度转换”策略。在该策略中，利用 uda 纤维单胞菌 E3-01 在适宜温度（35℃）下促进纤维素酶的产生，而在升高的培养温度（45℃）下实现更高效的酶促纤维素水解，此时细胞生长受到抑制以避免还原糖的消耗。结果表明，这种温度转换策略在水解纯纤维素材料（羧甲基纤维素、木聚糖、微晶纤维素和纤维二糖）和天然纤维素材料（稻壳、稻草、甘蔗渣和象草）时，能显著提高水解产物中还原糖（特别是单糖和二糖）的浓度。来自羧甲基纤维素和木聚糖的纤维素水解产物通过丁酸梭菌 CGS5 的暗发酵成功转化为 H₂，最大产氢量达到 4.79 mmol H₂/g 还原糖。
