초록
<P><B>Abstract</B></P><P>Increase in L‐serine production is of interest for industry. Here, we describe a？metabolic engineering approach to increase the production of L‐serine in a methylotrophic bacterium. <I>mxaF</I>, the gene encoding the large subunit of a methanol dehydrogenase, was cloned from <I>Methylobacterium</I> sp. MB200 through transposon mutagenesis. Deletion of <I>mxaF</I> gene prevented the strain to grow on methanol, suggesting that <I>mxaF</I> is involved in methanol metabolism. Overexpression of <I>mxaF</I> gene in the strain MB200 resulted in a fivefold increase in methanol dehydrogenase activity compared to the wild‐type. Resting cell assays showed that the recombinant strain accumulated 6·6？mg？ml<SUP>−1</SUP> L‐serine in 72？h with 30？mg？ml<SUP>−1</SUP> wet cells from 50？mg？ml<SUP>−1</SUP> glycine and 50？mg？ml<SUP>−1</SUP> methanol, representing a 1·5‐fold increment for L‐serine production in contrast to the wild‐type strain. These results demonstrate that the potential for improving the production of L‐serine can be achieved by overexpressing <I>mxaF</I> gene in methylotrophic bacteria.</P><P><B>Significance and Impact of the Study</B></P><P>The amount of L‐serine produced each year worldwide is relatively small compared with the amounts of the other amino acids and hence it is in great demand. Here, we describe a metabolic engineering approach to increase the production of L‐serine in a methylotrophic bacterium <I>Methylobacterium</I> sp. MB200. The result demonstrates that raising the output of L‐serine can be achieved by overexpressing <I>mxaF</I> gene in methylotrophic bacteria.</P>