Improvement of butanol production by the development and co-culture of C. acetobutylicum TSH1 and B. cereus TSH2
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Butanol fermentation comprises two successive and distinct stages, namely acidogenesis and solventogenesis. The current lack of clarity regarding the underlying metabolic regulation of fermentation impedes improvements in biobutanol production. Here, a proteomics study was performed in the acidogenesis phase, the lowest pH point (transition point), and the solventogenesis phase in the butanol-producing symbiotic system TSH06. Forty-two Clostridium acetobutylicum proteins demonstrated differential expression levels at different stages. The protein level of butanol dehydrogenase increased in the solventogenesis phase, which was in accordance with the trend of butanol concentration. Stress proteins were upregulated either at the transition point or in the solventogenesis phase. The cell division-related protein Maf was upregulated at the transition point. We disrupted the maf gene in C. acetobutylicum TSH1, and Bacillus cereus TSH2 was added to form a new symbiotic system. TSH06△maf produced 13.9 ± 1.0 g/L butanol, which was higher than that of TSH06 (12.3 ± 0.9 g/L). Butanol was furtherly improved in fermentation at variable temperature with neutral red addition for both TSH06 and TSH06△maf. The butanol titer of the maf deletion strain was higher than that of the wild type, although the exact mechanism remains to be determined.
KeywordsButanol Proteomics Phase transition Metabolic engineering TSH06 Symbiotic system
The authors thank Prof. Nigel P. Minton and Dr. John T. Heap for generous gift of ClosTron system. We would like to thank Editage (www.editage.cn) for English language editing.
This study was funded by the National Key R&D Program of China (2016YFE0131300), the National Natural Science Foundation of China (NO.21176141), the Tsinghua University Initiative Scientific Research Program (NO.2012THZ02289), and Norway Statoil Petroleum AS.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants performed by any of the authors.
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