Characterization of two novel butanol dehydrogenases involved in butanol degradation in syngas‐utilizing bacterium Clostridium ljungdahlii DSM 13528. (29th May 2013)

• Record Type: Journal Article
• Authors: Tan, Yang; Liu, Juanjuan; Liu, Zhen; Li, Fuli
• Is Part Of: Journal of basic microbiology. Volume 54:issue 9(2014:Sep.)
• Page Start: 996
• Page End: 1004
• Publication Date: 2013-05-29
• Subjects: Microbiology -- Periodicals; 579
• DOI: 10.1002/jobm.201300046
• Languages: English
• ISSNs: 0233-111X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="jobm201300046-sec-0001" sec-type="section"> <p>Syngas utilizing bacterium <italic>Clostridium ljungdahlii</italic> DSM 13528 is a promising platform organism for a whole variety of different biofuels and biochemicals production from syngas. During syngas fermentation, <italic>C. ljungdahlii</italic> DSM 13528 could convert butanol into butyrate, which significantly reduces productivity of butanol. However, there has been no any enzyme involved in the degradation of butanol characterized in <italic>C. ljungdahlii</italic> DSM 13528. In this study two genes, CLJU_c24880 and CLJU_c39950, encoding putative butanol dehydrogenase (designated as BDH1 and BDH2) were identified in the genome of <italic>C. ljungdahlii</italic> DSM 13528 and qRT‐PCR analysis showed the expression of <italic>bdh1</italic> and <italic>bdh2</italic> was significantly upregulated in the presence of 0.25% butanol. And the deduced amino acid sequence for BDH1 and BDH2 showed 69.85 and 68.04% identity with <italic>Clostridium acetobutylicum</italic> ADH1, respectively. Both BDH1 and BDH2 were oxygen‐sensitive and preferred NADP<sup>+</sup> as cofactor and butanol as optimal substrate. The optimal temperature and pH for BDH1 were at 55 °C and pH 7.5 and specific activity was 18.07 ± 0.01 µmol min<sup>−1</sup> mg<sup>−1</sup>. BDH2 was a thermoactive dehydrogenase with maximum activity at 65 °C and at pH 7.0. The specific activity for BDH2 was 11.21 ± 0.02 µmol min<sup>−1</sup> mg<sup>−1</sup>. This study provided important information for understanding the molecular mechanism of butanol degradation and determining the targets for gene knockout to improve the productivity of butanol from syngas in <italic>C. ljungdahlii</italic> DSM 13528 in future.</p> </sec> </abstract>