title: Characterization of salt-tolerant mutant for enhancement of L-threonine production in Escherichia coli.
abstract: Escherichia coli strain HS3, metabolically engineered to have Met(-), AHV(r), Ile(L) and AEC(r) characteristics, produced 58.0 g/l of L-threonine, but it was neither salt-tolerant nor osmotolerant; and the growth and threonine production of the strain were severely inhibited both by the addition of NaCl with a concentration higher than 2% and by the presence of glucose with a concentration higher than 10%. Therefore, salt-tolerant mutants were isolated. The salt-tolerant mutants, HS454 and HS528 which were derived from strain HS3, were both tolerant to salt (2%) and hyper-productive. The growth and L-threonine production by the mutant strain HS454 were almost unaffected by a glucose concentration lower than 10%, but gradually reduced with increasing glucose concentration, up to 15%. However, the mutant strain HS528 showed slightly enhanced growth and L-threonine production with increasing glucose concentration, up to 10-12.5%. Strains HS454 and HS528 produced 69.8 g/l and 74.0 g/l of L-threonine, respectively in a 5-1 jar fermentor.
authors.affiliation: Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Youngin, Kyungki-Do, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Song
authors.forename: H H
authors.initials: HH
authors.lastname: Lee
authors.forename: H H
authors.initials: HH
authors.lastname: Hyun
mesh_terms: D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D007700:Kinetics; D009154:Mutation; D011392:Proline / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D013912:Threonine / Q000096:biosynthesis*
chemical_list: D003470:Culture Media; D013912:Threonine; D012965:Sodium Chloride; D011392:Proline; D005947:Glucose