Continuous synthesis and excretion of the compatible solute ectoine by a transgenic, nonhalophilic bacterium.
The compatible solute 1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid (ectoine) acts in microorganisms as an osmotic counterweight against halostress and has attracted commercial attention as a protecting agent. Its production and application are restricted by the drawbacks of the discontinuous harvesting procedure involving salt shocks, which reduces volumetric yield, increases reactor corrosion, and complicates downstream processing. In order to synthesize ectoine continuously in less-aggressive media, we introduced the ectoine genes ectABC of the halophilic bacterium Chromohalobacter salexigens into an Escherichia coli strain using the expression vector pASK-IBA7. Under the control of a tet promoter, the transgenic E. coli synthesized 6 g liter-1 ectoine with a space-time yield of 40 mg liter-1 h-1, with the vast majority of the ectoine being excreted.
Schubert
Torsten
T
UFZ, Helmholtz Centre for Environmental Research, Department of Environmental Microbiology, Permoserstr. 15, 04318 Leipzig, Germany.
Maskow
Thomas
T
Benndorf
Dirk
D
Harms
Hauke
H
Breuer
Uta
U
D000599:Amino Acids, Diamino / Q000096:biosynthesis*; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D005822:Genetic Vectors; D044129:Halomonadaceae / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D013752:Tetracycline; D014169:Transformation, Bacterial
D000599:Amino Acids, Diamino; C045628:ectoine; D013752:Tetracycline