초록
<P><I>Klebsiella pneumoniae</I> is considered a good host strain for the production of 2,3-butanediol, which is a promising platform chemical with various industrial applications. In this study, three genes, including those encoding glucosyltransferase (<I>wabG</I>), lactate dehydrogenase (<I>ldhA</I>), and pyruvate formate-lyase (<I>pflB</I>), were disrupted in <I>K. pneumoniae</I> to reduce both its pathogenic characteristics and the production of several by-products. In flask cultivation with minimal medium, the yield of 2,3-butanediol from rationally engineered <I>K. pneumoniae</I> (Δ<I>wabG</I> Δ<I>ldhA</I> Δ<I>pflB</I>) reached 0.461 g/g glucose, which was 92.2% of the theoretical maximum, with a significant reduction in by-product formation. However, the growth rate of the <I>pflB</I> mutant was slightly reduced compared to that of its parental strain. Comparison with similar mutants of <I>Escherichia coli</I> suggested that the growth defect of <I>pflB</I>-deficient <I>K. pneumoniae</I> was caused by redox imbalance rather than reduced level of intracellular acetyl coenzyme A (acetyl-CoA). From an analysis of the transcriptome, it was confirmed that the removal of <I>pflB</I> from <I>K. pneumoniae</I> significantly repressed the expression of genes involved in the formate hydrogen lyase (FHL) system.</P>