Genetic engineering of Candida utilis yeast for efficient production of L-lactic acid.
Polylactic acid is receiving increasing attention as a renewable alternative for conventional petroleum-based plastics. In the present study, we constructed a metabolically-engineered Candida utilis strain that produces L-lactic acid with the highest efficiency yet reported in yeasts. Initially, the gene encoding pyruvate decarboxylase (CuPDC1) was identified, followed by four CuPDC1 disruption events in order to obtain a null mutant that produced little ethanol (a by-product of L-lactic acid). Two copies of the L-lactate dehydrogenase (L-LDH) gene derived from Bos taurus under the control of the CuPDC1 promoter were then integrated into the genome of the CuPdc1-null deletant. The resulting strain produced 103.3 g/l of L-lactic acid from 108.7 g/l of glucose in 33 h, representing a 95.1% conversion. The maximum production rate of L-lactic acid was 4.9 g/l/h. The optical purity of the L-lactic acid was found to be more than 99.9% e.e.
Ikushima
Shigehito
S
Central Laboratories for Frontier Technology, KIRIN Holdings Co., Ltd., Yokohama, Kanagawa, Japan. Shigehito_Ikushima@kirin.co.jp
Fujii
Toshio
T
Kobayashi
Osamu
O
Yoshida
Satoshi
S
Yoshida
Aruto
A
D000818:Animals; D002175:Candida / Q000235:genetics* / Q000378:metabolism*; D002417:Cattle; D003001:Cloning, Molecular; D005285:Fermentation; D005818:Genetic Engineering / Q000379:methods*; D019344:Lactic Acid / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009154:Mutation; D011767:Pyruvate Decarboxylase / Q000235:genetics / Q000378:metabolism
D019344:Lactic Acid; D011767:Pyruvate Decarboxylase