초록
<P><B>Abstract</B></P><P><B>Aims</B></P><P>To investigate the role of phosphoenolpyruvate (PEP) carboxylation in cell metabolism in <I>Klebsiella pneumoniae</I>.</P><P><B>Methods and Results</B></P><P>The effects of deleting <I>pck</I>, which encodes PEP carboxykinase (PCK), and/or <I>ppc</I>, which encodes PEP carboxylase (PPC), on growth, enzyme activity and metabolite formation of <I>Kl. pneumoniae</I> were investigated. A self‐regulatory mechanism of PEP carboxylation was found in <I>ppc</I>‐ or <I>pck</I>‐deficient mutants, which resulted in almost no change in succinate formation. However, almost no growth was observed in a <I>ppc</I>‐ and <I>pck</I>‐deficient mutant. Interestingly, only deleting <I>pck</I> affected the energy metabolism and promoted aerobic cell growth. Under micro‐aerobic conditions, although there was only a small (8·1%) increase of 1,3‐propanediol production by such <I>pck</I>‐deficient mutant during a 2‐l fed‐batch process, the by‐products 2,3‐butanediol and acetate significantly decreased by 73·0% and 54·8%, respectively, compared with those in the parent strain.</P><P><B>Conclusions</B></P><P>PEP carboxylation could be a critical anaplerotic reaction for converting C3 to C4 metabolites in the central metabolism of <I>Kl. pneumoniae</I>.</P><P><B>Significance and Impact of the Study</B></P><P>This study is the first to identify the critical role of PEP carboxylation, as well as those of PPC and PCK, which are responsible for this reaction, in <I>Kl. pneumoniae</I>. In addition, the <I>pck</I>‐deficient mutant was proven to be a valuable 1,3‐propanediol producer.</P>