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- Title
Rational modification of tricarboxylic acid cycle for improving l-lysine production in <italic>Corynebacterium glutamicum</italic>.
- Authors
Xu, Jian-Zhong; Wu, Ze-Hua; Gao, Shi-Jun; Zhang, Weiguo
- Abstract
Background: Oxaloacetate (OAA) and l-glutamate are essential precursors for the biosynthesis of l-lysine. Reasonable control of all potentially rate-limiting steps, including the precursors supply rate, is of vital importance to maximize the efficiency of l-lysine fermentation process. Results: In this paper, we have rationally engineered the tricarboxylic acid (TCA) cycle that increased the carbon yield (from 36.18 to 59.65%), final titer (from 14.47 ± 0.41 to 23.86 ± 2.16 g L−1) and productivity (from 0.30 to 0.50 g L−1 h−1) of l-lysine by <italic>Corynebacterium glutamicum</italic> in shake-flask fermentation because of improving the OAA and l-glutamate availability. To do this, the phosphoenolpyruvate–pyruvate–oxaloacetate (PEP–pyruvate–OAA) node's genes <italic>ppc</italic> and <italic>pyc</italic> were inserted in the genes <italic>pck</italic> and <italic>odx</italic> loci, the P1 promoter of the TCA cycle's gene <italic>gltA</italic> was deleted, and the nature promoter of glutamate dehydrogenase-coding gene <italic>gdh</italic> was replaced by Ptac-M promoter that resulted in the final engineered strain <italic>C. glutamicum</italic> JL-69Ptac-M<italic>gdh</italic>. Furthermore, the suitable addition of biotin accelerates the l-lysine production in strain JL-69Ptac-M<italic>gdh</italic> because it elastically adjusts the carbon flux for cell growth and precursor supply. The final strain JL-69Ptac-M<italic>gdh</italic> could produce 181.5 ± 11.74 g L−1 of l-lysine with a productivity of 3.78 g L−1 h−1 and maximal specific production rate (<italic>q</italic>Lys, max.) of 0.73 ± 0.16 g g−1 h−1 in fed-batch culture during adding 2.4 mg L−1 biotin with four times. Conclusions: Our results reveal that sufficient biomass, OAA and l-glutamate are equally important in the development of l-lysine high-yielding strain, and it is the first time to verify that fed-batch biotin plays a positive role in improving l-lysine production.
- Subjects
OXALACETATE; BIOSYNTHESIS; LYSINE; FERMENTATION; GLUTAMIC acid
- Publication
Microbial Cell Factories, 2018, Vol 17, Issue 1, pN.PAG
- ISSN
1475-2859
- Publication type
Article
- DOI
10.1186/s12934-018-0958-z