Dataset Information

Synthetic engineering of Corynebacterium crenatum to selectively produce acetoin or 2,3-butanediol by one step bioconversion method.

ABSTRACT:

Background

Acetoin (AC) and 2,3-butanediol (2,3-BD) as highly promising bio-based platform chemicals have received more attentions due to their wide range of applications. However, the non-efficient substrate conversion and mutually transition between AC and 2,3-BD in their natural producing strains not only led to a low selectivity but also increase the difficulty of downstream purification. Therefore, synthetic engineering of more suitable strains should be a reliable strategy to selectively produce AC and 2,3-BD, respectively.

Results

In this study, the respective AC (alsS and alsD) and 2,3-BD biosynthesis pathway genes (alsS, alsD, and bdhA) derived from Bacillus subtilis 168 were successfully expressed in non-natural AC and 2,3-BD producing Corynebacterium crenatum, and generated recombinant strains, C. crenatum SD and C. crenatum SDA, were proved to produce 9.86 g L^-1 of AC and 17.08 g L^-1 of 2,3-BD, respectively. To further increase AC and 2,3-BD selectivity, the AC reducing gene (butA) and lactic acid dehydrogenase gene (ldh) in C. crenatum were then deleted. Finally, C. crenatum?butA?ldh SD produced 76.93 g L^-1 AC in one-step biocatalysis with the yield of 0.67 mol mol^-1. Meanwhile, after eliminating the lactic acid production and enhancing 2,3-butanediol dehydrogenase activity, C. crenatum?ldh SDA synthesized 88.83 g L^-1 of 2,3-BD with the yield of 0.80 mol mol^-1.

Conclusions

The synthetically engineered C. crenatum?butA?ldh SD and C. crenatum?ldh SDA in this study were proved as an efficient microbial cell factory for selective AC and 2,3-BD production. Based on the insights from this study, further synthetic engineering of C. crenatum for AC and 2,3-BD production is suggested.

SUBMITTER: Zhang X

PROVIDER: S-EPMC6683508 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

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Publications

Synthetic engineering of Corynebacterium crenatum to selectively produce acetoin or 2,3-butanediol by one step bioconversion method.

Zhang Xian X Han Rumeng R Bao Teng T Zhao Xiaojing X Li Xiangfei X Zhu Manchi M Yang Taowei T Xu Meijuan M Shao Minglong M Zhao Youxi Y Rao Zhiming Z

Microbial cell factories 20190806 1

<h4>Background</h4>Acetoin (AC) and 2,3-butanediol (2,3-BD) as highly promising bio-based platform chemicals have received more attentions due to their wide range of applications. However, the non-efficient substrate conversion and mutually transition between AC and 2,3-BD in their natural producing strains not only led to a low selectivity but also increase the difficulty of downstream purification. Therefore, synthetic engineering of more suitable strains should be a reliable strategy to selec ...[more]

PMID: 31387595

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Project description:UNLABELLED: BACKGROUND:Acetoin and 2,3-butanediol are two important biorefinery platform chemicals. They are currently fermented below 40°C using mesophilic strains, but the processes often suffer from bacterial contamination. RESULTS:This work reports the isolation and identification of a novel aerobic Geobacillus strain XT15 capable of producing both of these chemicals under elevated temperatures, thus reducing the risk of bacterial contamination. The optimum growth temperature was found to be between 45 and 55°C and the medium initial pH to be 8.0. In addition to glucose, galactose, mannitol, arabionose, and xylose were all acceptable substrates, enabling the potential use of cellulosic biomass as the feedstock. XT15 preferred organic nitrogen sources including corn steep liquor powder, a cheap by-product from corn wet-milling. At 55°C, 7.7?g/L of acetoin and 14.5?g/L of 2,3-butanediol could be obtained using corn steep liquor powder as a nitrogen source. Thirteen volatile products from the cultivation broth of XT15 were identified by gas chromatography-mass spectrometry. Acetoin, 2,3-butanediol, and their derivatives including a novel metabolite 2,3-dihydroxy-3-methylheptan-4-one, accounted for a total of about 96% of all the volatile products. In contrast, organic acids and other products were minor by-products. ?-Acetolactate decarboxylase and acetoin:2,6-dichlorophenolindophenol oxidoreductase in XT15, the two key enzymes in acetoin metabolic pathway, were found to be both moderately thermophilic with the identical optimum temperature of 45°C. CONCLUSIONS:Geobacillus sp. XT15 is the first naturally occurring thermophile excreting acetoin and/or 2,3-butanediol. This work has demonstrated the attractive prospect of developing it as an industrial strain in the thermophilic fermentation of acetoin and 2,3-butanediol with improved anti-contamination performance. The novel metabolites and enzymes identified in XT15 also indicated its strong promise as a precious biological resource. Thermophilic fermentation also offers great prospect for improving its yields and efficiencies. This remains a core aim for future work.

Dataset Information

Synthetic engineering of Corynebacterium crenatum to selectively produce acetoin or 2,3-butanediol by one step bioconversion method.

Background

Results

Conclusions

Publications

Synthetic engineering of Corynebacterium crenatum to selectively produce acetoin or 2,3-butanediol by one step bioconversion method.

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