L-丝氨酸产生菌的分离筛选及发酵条件

Screening of L-Serine Producer and the Fermentation Conditions in Shake-Flask Culture

在含50 mL/L的甲醇、5 g/L的甘氨酸的基本培养基平板上,从土壤中分离出130多株细菌,测定了它们利用甘氨酸生产L 丝氨酸的能力.获得了一株产 L 丝氨酸较好的菌株 A3,L 丝氨酸产量最高为1.4 g/L,分类学鉴定为微球菌科(Micrococcaceae),对菌株A3利用甘氨酸发酵生产L 丝氨酸的发酵条件进行了初步研究,包括甘氨酸和甲醇添加量,不同碳源、氮源,初始pH值以及发酵时间对产酸的影响.结果表明,菌株 A3 在不添加甲醇、只以甘氨酸为惟一碳源的发酵培养基中也能产L 丝氨酸,培养基中较高质量浓度的甘氨酸存在对L 丝氨酸生产是必需的.添加葡萄糖、甘油等外源碳源对菌体生长有利但不利于L 丝氨酸的生产.

About 130 microorganisms isolated from soil on the minimal medium containing 50 mL/L methanol and 5 g/L glycine were examined for L-serine accumulation. Strain A3, a bacterium, was identified as Micrococcaceae. The strain produced 1.4 g/L L-serine when glycine was added in the growth medium. The cultural conditions of converting glycine to L-serine were investigated, including initial methanol and glycine concentration, carbon sources, nitrogen sources, initial pH of medium and time course of L-serine production. The results showed that the strain A3 could produce L-serine in shake culture at 31 ℃ in the medium containing glycine, the sole carbon source. The high concentration of glycine was necessary for L-serine accumulation during the fermentation. The addition of glucose, glycerol, etc. In the glycine containing medium was beneicial to the cell growth but not favorable for the production of L-serine.