Zhang Qin, Zhang Liang, Ding Zhongyang, Wang Zhengxiang, Shi Guiyang
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China.
Sheng Wu Gong Cheng Xue Bao. 2011 Jul;27(7):1024-31.
In order to obtain a yeast strain able to produce L-lactic acid under the condition of low pH and high lactate content, one wild acid-resistant yeast strain isolated from natural samples, was found to be able to grow well in YEPD medium (20 g/L glucose, 20 g/L tryptone, 10 g/L yeast extract, adjusted pH 2.5 with lactic acid) without consuming lactic acid. Based on further molecular biological tests, the strain was identified as Candida magnolia. Then, the gene ldhA, encoding a lactate dehydrogenase from Rhizopus oryzae, was cloned into a yeast shuttle vector containing G418 resistance gene. The resultant plasmid pYX212-kanMX-ldhA was introduced into C. magnolia by electroporation method. Subsequently, a recombinant L-lactic acid producing yeast C. magnolia-2 was obtained. The optimum pH of the recombinant yeast is 3.5 for lactic acid production. Moreover, the recombinant strain could grow well and produce lactic acid at pH 2.5. This recombinant yeast strain could be useful for producing L-lactic acid.
为了获得能够在低pH值和高乳酸含量条件下生产L-乳酸的酵母菌株，从天然样品中分离出一株野生耐酸酵母菌株，发现其能够在YEPD培养基（20 g/L葡萄糖、20 g/L胰蛋白胨、10 g/L酵母提取物，用乳酸调节pH值至2.5）中良好生长且不消耗乳酸。基于进一步的分子生物学测试，该菌株被鉴定为木兰假丝酵母。然后，将编码米根霉乳酸脱氢酶的基因ldhA克隆到含有G418抗性基因的酵母穿梭载体中。通过电穿孔法将所得质粒pYX212-kanMX-ldhA导入木兰假丝酵母。随后，获得了一株重组产L-乳酸酵母木兰假丝酵母-2。重组酵母产乳酸的最适pH值为3.5。此外，该重组菌株在pH 2.5时能够良好生长并产生乳酸。这种重组酵母菌株可用于生产L-乳酸。
