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Limitation of thiamine pyrophosphate supply to growing Escherichia coli switches metabolism to efficient d ‐lactate formation
Author(s) -
Tian Kangming,
Niu Dandan,
Liu Xiaoguang,
Prior Bernard A.,
Zhou Li,
Lu Fuping,
Singh Suren,
Wang Zhengxiang
Publication year - 2016
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.25699
Subject(s) - thiamine pyrophosphate , pyrophosphate , escherichia coli , thiamine , chemistry , metabolism , biochemistry , microbial metabolism , bacteria , biology , cofactor , enzyme , gene , genetics
Efficient production of d ‐lactate by engineered Escherichia coli entails balancing cell growth and product synthesis. To develop a metabolic switch to implement a desirable transition from cell growth to product fermentation, a thiamine auxotroph B0013‐080A was constructed in a highly efficient d ‐lactate producer E. coli strain B0013‐070. This was achieved by inactivation of thiE , a gene encoding a thiamine phosphate synthase for biosynthesis of thiamine monophosphate. The resultant mutant B0013‐080A failed to grow on the medium in the absence of thiamine yet growth was restored when exogenous thiamine was provided. A linear relationship between cell mass formation and amount of thiamine supplemented was mathematically determined in a shake flask experiment and confirmed in a 7‐L bioreactor system. This calculation revealed that ∼95–96 thiamine molecules per cell were required to satisfy cell growth. This relationship was employed to develop a novel fermentation process for d ‐lactate production by using thiamine as a limiting condition. A d ‐lactate productivity of 4.11 g · L −1 · h −1 from glycerol under microaerobic condition and 3.66 g · L −1 · h −1 from glucose under anaerobic condition was achieved which is 19.1% and 10.2% higher respectively than the parental strain. These results revealed a convenient and reliable method to control cell growth and improve d ‐lactate fermentation. This control strategy could be applied to other biotechnological processes that require optimal allocation of carbon between cell growth and product formation. Biotechnol. Bioeng. 2016;113: 182–188. © 2015 Wiley Periodicals, Inc.