一株高耐受性乳酸菌的分离及其在木质纤维素发酵生产高浓度L-乳酸中的应用

Isolation of a Highly Tolerant Lactic Acid Bacterium and High-Titer L-Lactic Acid Fermentation Using Lignocellulosic Feedstock

利用资源丰富的纤维质原料生产新一代可降解聚乳酸塑料的单体原料L-乳酸,是目前一个极为重要的研究热点和产业方向。从高温纤维乙醇发酵介质中分离到一株高耐受性乳酸菌,经16S rDNA分子生物学鉴定为乳酸片球菌(Pediococcus acidilactici),并命名为P.acidilacticiDQ2。此菌株具有极为优异的耐高温和耐受高浓度木质纤维素降解产物的特性,这一特性可能与母株的环境变异和体系中存在的调控物质有关。利用该乳酸菌以稀酸预处理后的玉米秸秆为原料进行同步糖化与乳酸发酵,发酵液中的乳酸质量浓度为75 g/L,乳酸对纤维素得率达到0.63 g/g,具备了纤维素乳酸产业化生产的潜力。

Production of L-lactic acid from abundant lignocellulosic resource has become an important trend for research and commercialization because poly-lactic acid（PLA） from L-lactic acid is regarded as the next generation biodegradable plastic.A highly tolerant lactic acid bacterium（LAB） was isolated from the cellulosic ethanol fermentation broth at elevated temperature and identified as Pediococcus acidilactici using 16S rDNA and phylogenic analysis.P.acidilactici DQ2 is high thermotolerance and high resistance to the lignocellulose derived inhibitors.These characteristics probably are associated with environmental mutation and stimulating factors naturally present in the lignocellulosic hydrolysate system.The titer and yield of L-lactic acid in the simultaneous saccharification and fermentation（SSF） using the diluted acid pretreated corn stover（CS） were 75 g/L and 0.63 g/g cellulose,respectively,and showed a great potential for cellulosic lactic acid production for the future commercial application.