title: Overexpression of the methanol dehydrogenase gene mxaF in Methylobacterium sp. MB200 enhances L-serine production.
abstract: 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. mxaF, the gene encoding the large subunit of a methanol dehydrogenase, was cloned from Methylobacterium sp. MB200 through transposon mutagenesis. Deletion of mxaF gene prevented the strain to grow on methanol, suggesting that mxaF is involved in methanol metabolism. Overexpression of mxaF 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(-1) L-serine in 72 h with 30 mg ml(-1) wet cells from 50 mg ml(-1) glycine and 50 mg ml(-1) 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 mxaF gene in methylotrophic bacteria.
  
  
  CONCLUSIONS
  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 Methylobacterium sp. MB200. The result demonstrates that raising the output of L-serine can be achieved by overexpressing mxaF gene in methylotrophic bacteria.
authors.affiliation: College of Life Science and Technology, Guangxi University, Nanning, China.|Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
authors.forename: H
authors.initials: H
authors.lastname: Chao
authors.affiliation: State Key Laboratory for Conservation and Utilization of Agricultural Bioresources in the Subtropics, Nanning, China.
authors.forename: B
authors.initials: B
authors.lastname: Wu
authors.affiliation: College of Life Science and Technology, Guangxi University, Nanning, China.|State Key Laboratory for Conservation and Utilization of Agricultural Bioresources in the Subtropics, Nanning, China.
authors.forename: P
authors.initials: P
authors.lastname: Shen
mesh_terms: D000429:Alcohol Oxidoreductases / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics; D060847:Metabolic Engineering / Q000379:methods*; D000432:Methanol / Q000378:metabolism; D020580:Methylobacterium / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D012694:Serine / Q000096:biosynthesis*
chemical_list: D004251:DNA Transposable Elements; D012694:Serine; D000429:Alcohol Oxidoreductases; C019641:alcohol dehydrogenase (acceptor); D000432:Methanol
keywords: L-serine; metabolic engineering; methanol; methanol dehydrogenase; transposon mutagenesis