重组大肠杆菌利用木糖发酵产高纯度L-乳酸

对重组大肠杆菌JH16利用木糖产高纯度的三一乳酸进行研究。通过无氧管驯化EscherwhiacdiJH12菌株得到E．coliJH16，驯化后的菌株茵体浓度提高了31％，乙酸积累减少了43％；在摇瓶中考察不同Mg2＋浓度对EcoliJHl6产三一乳酸的影响，确定最适Mg2＋质量浓度为0．25g/L；EcoEJH16以60g/L木糖为C源，在7L全自动发酵罐中添加0．25g／LMg2＋，乳酸积累量提高了18％，达38．18g/L，乳酸纯度高达95％；E．coliJH16在30g／L木糖和30g／L葡萄糖混合C源中，优先利用葡萄糖，当葡萄糖质量浓度低于1．56g/L后，菌体开始利用木糖进行乳酸发酵，最终得到39g／L乳酸。

Fermentation production of L-lactate from xylose by engineered Escherichia coli

Under anaerobic conditions, the characteristics of lactate fermentation were investigated by engineered Escherichia coli JH16 using xylose as carbon source supplied into the culture medium. E. coli JH12 was domesticated in anaerobic tube,and the resulted strain E. coli JH16 cell mass was increased by 31% ,the acetate concentration was decreased by 43%. In addition,the effect of Mg2＋ on the production of lactate was studied,and the optimal concentration was 0. 25 g/L. L-lactic acid production of the strain in a 7-L fermenter was evaluated in 60 g/L xylose. The lactate concentration achieved 38. 18 g/L,increased by 18% in 0. 25 g/L Mg2＋. The purity of lactate achieved to 95%. When cultured in mixture of 30 g/L glucose and 30 g/L xylose,lactate reached 39 g/L when the glucose concentration was below 1.56 g/L.