Earticle

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영어

We investigated Lactate fermentation metabolism in Lactobacillus coryniformis subsp. torquens KCTC 3535 for production of optically pure D-lactate. L. coryniformis was known to produce D-lactate as dominant fermentation product at cultivation temperature around 30 ℃. However, considerable production of L-lactate was observed when fermentation temperature was over 40 ℃. Because optically pure isomers are produced using chiral-specific D- or L-lactate dehydrogenase (D- or L-LDH), we assumed that the thermostability of L-LDHs are significantly higher than that of D-LDHs, which may be a reason why L-lactate was produced at higher cultivation temperature. To elucidate above assumption, firstly we synthesized two kinds of D-LDH gene and six kinds of L-LDH gene based on the genomic information of Lactobacillus coryniformis subsp. torquens KCTC 3535. All the D-LDHs and L-LDHs were cloned and expressed in Escherichia coli. Among the total 8 LDHs tested, Only five LDHs including D-LDH1, 2 and L-LDH2, 3 and 1702 showed activity. In addition, Through Western blotting analysis for LDHs extracted from L. coryniformis cells, D-LDH1, L-LDH2 and L-LDH3 were found dominantly expressed lactate dehydrogenase, which imply that three LDHs play a major role in the synthesis of lactate from pyruvate. T50 10 values, which is the temperature at which 50% of initial enzymatic activity remains after 10 min heat treatment, of each LDHs were determined 39.5, 39.9 and 58.6 ℃, respectively. Thermally stable property of L-LDH3 compared with that of D-LDH1 can be a major reason why the enantiopurity of D-lactate was decreased from 99 % to 50 % at relatively high fermentation temperature over 40 ℃. Elucidation of temperature effect on the quality of D-lactate will give a direction for metabolic engineer to develop efficient microbial strain for optically pure D-lactate.

키워드

저자

• Hyojin HWANG [ Dept. of Biotechnology, kwangwoon University, Seoul. ]

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간행물

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• 간행물명

  한국생물공학회 학술대회

• 간기

  반년간

• 수록기간

  1985~2013

• 십진분류

  KDC 476 DDC 576