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- Title
Metabolic engineering of Bacillus subtilis for chiral pure meso-2,3-butanediol production.
- Authors
Jing Fu; Guangxin Huo; Lili Feng; Yufeng Mao; Zhiwen Wang; Hongwu Ma; Tao Chen; Xueming Zhao
- Abstract
Background: 2,3-Butanediol (2,3-BD) with low toxicity to microbes, could be a promising alternative for biofuel production. However, most of the 2,3-BD producers are opportunistic pathogens that are not suitable for industrialscale fermentation. In our previous study, wild-type Bacillus subtilis 168, as a class I microorganism, was first found to generate only d-(-)-2,3-BD (purity >99 %) under low oxygen conditions. Results: In this work, B. subtilis was engineered to produce chiral pure meso-2,3-BD. First, D-(-)-2,3-BD production was abolished by deleting D-(-)-2,3-BD dehydrogenase coding gene bdhA, and acoA gene was knocked out to prevent the degradation of acetoin (AC), the immediate precursor of 2,3-BD. Next, both pta and ldh gene were deleted to decrease the accumulation of the byproducts, acetate and L-lactate. We further introduced the meso-2,3-BD dehydrogenase coding gene budC from Klebsiella pneumoniae CICC10011, as well as overexpressed alsSD in the tetra-mutant (acoAΔbdhAΔpta ldh) to achieve the efficient production of chiral meso-2,3-BD. Finally, the pool of NADH availability was further increased tofacilitate the conversion of meso-2,3-BD from AC by overexpressing udhA gene (coding a soluble transhydrogenase) and low dissolved oxygen control during the cultivation. Under microaerobic oxygen conditions, the best strain BSF9 produced 103.7 g/L meso-2,3-BD with a yield of 0.487 g/g glucose in the 5-L batch fermenter, and the titer of the main byproduct AC was no more than 1.1 g/L. Conclusion: This work offered a novel strategy for the production of chiral pure meso-2,3-BD in B. subtilis. To our knowledge, this is the first report indicating that metabolic engineered B. subtilis could produce chiral meso-2,3-BD with high purity under limited oxygen conditions. These results further demonstrated that B. subtilis as a class I microorganism is a competitive industrial-level meso-2,3-BD producer.
- Subjects
BIOMASS energy; BUTANEDIOL manufacturing; BACILLUS subtilis; COFACTORS (Biochemistry); BUTANEDIOL
- Publication
Biotechnology for Biofuels, 2016, Vol 9, p1
- ISSN
1754-6834
- Publication type
Article
- DOI
10.1186/s13068-016-0502-5