Engineering of Hydroxyectoine Production based on the Methylomicrobium alcaliphilum

Ectoine is an osmoprotector that is synthesized by many halophilic and halotolerant bacteria in response to osmotic stress. The halotolerant methanotroph Methylomicrobium alcaliphilum 20Z was genetically modified to produce ectoine derivative hydroxyectoine by introduction of the gene encoding ectoine hydroxylase EctD from Pseudomonas stutzeri DSM5190T. In the cells of the methanotroph transformed by the plasmid pMHA200 carrying ectD under control of either constitutive Pmxa promoter of methanol dehydrogenase or Pect promoter of the native ectABCask operon, most of intracellular ectoine was converted to hydroxyectoine. Cells of the methanotroph expressing the chromosomally located ectD gene accumulated ectoine and hydroxyectoine in almost equal ratio. Here we first showed that M. alcaliphilum 20Z can be appropriate strain to design hydroxyectoine producer from methane or methanol.