芽孢杆菌BCS 13002的鉴定及同步糖化发酵生产高光学纯度L-乳酸

Identification of a Bacillus coagulans and Production of High Optical Purity L-Lactic Acid via Synchronous Saccharifying Fermentation

从泡菜中分离得到一株芽孢杆菌,经16S RNA及生理生化鉴定为凝结芽孢杆菌(BCS 13002).文中研究了碳源、中和剂对菌株生产L-乳酸的影响,并在5 L发酵罐中分别以葡萄糖及玉米淀粉为碳源进行分批补料发酵和同步糖化发酵(SSF)的研究.结果表明,葡萄糖是最合适的碳源,使用木糖和玉米淀粉作为碳源均不利于L-乳酸的产生;使用NaOH作为中和剂的效果优于Ca(OH)_2和CaCO_3.在发酵罐中以葡萄糖为碳源进行分批补料发酵,得到L-乳酸含量为115.86 g/L,糖酸转化率约为82.31%,并证明MnSO_4·H_2O和MgCl_2·6H_2O在发酵中有特殊的作用.以玉米淀粉为原料同步糖化发酵,得到L-乳酸123.3 g/L,糖酸转化率约为70.03%,产品中L-乳酸的光学纯度均达到99.8%以上.

A Bacillus coagulans( BCS 13002) isolated from pickle was identified by using 16S RNA and on the basis of physiology and biochemistry,and the effects of carbon source and neutralizer on the production of L-lactic acid were analyzed. Then,the fed-batch fermentation with glucose and the synchronous saccharifying fermentation( SSF) with corn starch were respectively carried out at 5 L fermentation tanks. The results show that( 1) glucose is a kind of ideal carbon source,while xylose and corn starch are not beneficial to the production of L-lactic acid;( 2) as a kind of neutralizer,NaOH is better than Ca( OH)_2 and CaCO_3;( 3) through the fed-batch fermentation with glucose in a tank,the L-lactic acid content reaches up to 115. 86 g/L with a sugar acid conversion ratio of about 82. 31% ,and MnSO_4·H_2O and MgCl_2·6 H_2O play a special role in the fermentation; and( 4) through the synchronous saccharifying fermentation with corn starch,the L-lactic acid content reaches up to 123. 3 g/L,with a sugar acid conversion ratio of 70. 03 % and an optical purity of L-lactic acid of more than 99. 8% .