Introducing a single secondary alcohol dehydrogenase into butanol-tolerant Clostridium acetobutylicum Rh8 switches ABE fermentation to high level IBE fermentation

Zongjie Dai, Hongjun Dong, Yan Zhu, Yanping Zhang, Yin Li, Yanhe Ma

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Background: Previously we have developed a butanol tolerant mutant of Clostridium acetobutylicum Rh8, from the wild type strain DSM 1731. Strain Rh8 can tolerate up to 19g/L butanol, with solvent titer improved accordingly, thus exhibiting industrial application potential. To test if strain Rh8 can be used for production of high level mixed alcohols, a single secondary alcohol dehydrogenase from Clostridium beijerinckii NRRL B593 was overexpressed in strain Rh8 under the control of thl promoter. Results: The heterogenous gene sADH was functionally expressed in C. acetobutylicum Rh8. This simple, one-step engineering approach switched the traditional ABE (acetone-butanol-ethanol) fermentation to IBE (isopropanol-butanol-ethanol) fermentation. The total alcohol titer reached 23.88g/l (7.6g/l isopropanol, 15g/l butanol, and 1.28g/l ethanol) with a yield to glucose of 31.42%. The acid (butyrate and acetate) assimilation rate in isopropanol producing strain Rh8(psADH) was increased. Conclusions: The improved butanol tolerance and the enhanced solvent biosynthesis machinery in strain Rh8 is beneficial for production of high concentration of mixed alcohols. Strain Rh8 can thus be considered as a good host for further engineering of solvent/alcohol production. 

Original languageEnglish
Article number44
Number of pages10
JournalBiotechnology for Biofuels
Publication statusPublished - 28 Jun 2012
Externally publishedYes


  • Acetone-butanol-ethanol (ABE) fermentation
  • Butanol tolerance
  • Clostridium acetobutylicum
  • Isopropanol-butanol-ethanol (IBE) fermentation
  • Secondary alcohol dehydrogenase

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