[Cloning, expression and characterization of alcohol dehydrogenase and aldehyde dehydrogenase from Bacillus pseudofirmus OF4].

To clone and characterize the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) from Bacillus pseudofirmus OF4. Genes of adh and aldh were cloned by PCR; expression vectors pET-Ahd and pET-Aldh were constructed and expressed in Escherichia coli BL21 (DE3). After Ni-NTA column chromatography purification, the protein was characterized. The optimal temperature and pH of ALDH was 35 degrees C and 8.0, the specific activities of ALDH was 979.6 U/mg protein, the thermostability at 25 degrees C and 35 degrees C was better than at 45 degrees C. Although the expression level of ADH was too low to purify, but it was found that ADH had high catalytic activities by experiments of co-expression and ethanol tolerance. Adh and aldh from B. pseudofirmus OF4 were cloned successfully. Co-expression of double genes could greatly increase the host strain on ethanol tolerance.