초록
<P>Syngas utilizing bacterium <I>Clostridium ljungdahlii</I> DSM 13528 is a promising platform organism for a whole variety of different biofuels and biochemicals production from syngas. During syngas fermentation, <I>C. ljungdahlii</I> 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 <I>C. ljungdahlii</I> 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 <I>C. ljungdahlii</I> DSM 13528 and qRT‐PCR analysis showed the expression of <I>bdh1</I> and <I>bdh2</I> 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 <I>Clostridium acetobutylicum</I> 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 <I>C. ljungdahlii</I> DSM 13528 in future.</P>