초록
<P>The alcohol dehydrogenase promoter P<SUB>adhE</SUB> and mixed acid fermentation pathway deficient mutants of <I>Escherichia coli</I> were employed to produce poly(3-hydroxybutyrate) (P3HB) under microaerobic condition. The <I>E. coli</I> mutant with <I>ackA-pta, poxB, ldhA</I>, and <I>adhE</I> deletions accumulated 0.67 g/L P3HB, up to 78.84% of cell dry weight in tube cultivation. The deletion of pyruvate formate-lyase gene <I>pflB</I> drastically decreased P3HB production and P3HB content to 0.09 g/L and 24.44%, respectively. Overexpressing <I>pflB</I> via the plasmid in its knocked out mutant restored cell growth and P3HB accumulation, indicating the importance of the pyruvate formate-lyase in microaerobic carbon metabolism. The engineered <I>E. coli</I> BWapld (pWYC09) produced 5.00 g/L P3HB from 16.50 g/L glucose in 24 h batch fermentation, and P3HB production yield from glucose was 0.30 g/g, which reached up to 63% of maximal theoretical yield.</P>