[Metabolic engineering of wild acid-resistant yeast for L-lactic acid production].
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.
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China.
Qin
Q
Zhang
Liang
L
Zhang
Zhongyang
Z
Ding
Zhengxiang
Z
Wang
Guiyang
G
Shi
D002175:Candida / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005822:Genetic Vectors / Q000235:genetics; D007770:L-Lactate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D019344:Lactic Acid / Q000096:biosynthesis*; D060847:Metabolic Engineering; D011995:Recombination, Genetic; D012233:Rhizopus / Q000201:enzymology / Q000235:genetics*; D014169:Transformation, Bacterial
D019344:Lactic Acid; D007770:L-Lactate Dehydrogenase