title: [Selection of acetate-tolerant mutants from Escherichia coli DH5alpha and the metabolic properties of mutant DA19].
abstract: Esherichia coli DH5alpha is one of the widely used host strains in genetic engineering. However, foreign gene expression level in this strain is seriously inhibited due to its great sensitivity to the accumulated metabolite, acetate. This study aimed at improving the tolerance of this strain against acetate. Cells of E. coli DH5alpha were irradiated with 60Co, and subsequently continuous culture of the irradiated cells was conducted with gradual increase in the dilution rate and the selective pressure, acetate concentration in the medium. The mutants were picked up on MA plates which contained 5g/L sodium acetate. 5 strains with great improvement in acetate tolerance were obtained, among which DA19 was the best. In cultivation of DA19 in complex media YPS and YPS2G, the cell density, maximum specific growth rate and acetate produced were respectively 1.17 and 1.05, 1.08 and 1.27, and 0.06 and 0.59 times of those of DH5alpha. In a chemically defined medium, the cell density of DA19 was 3.4-fold of that of DH5alpha. The cell density of DA19 in a medium containing 10g/L sodium acetate was comparable to that of DH5alpha in the same medium without the addition of acetate.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Caiqing
authors.initials: C
authors.lastname: Zhu
authors.forename: Qin
authors.initials: Q
authors.lastname: Ye
mesh_terms: D000085:Acetates / Q000378:metabolism*; D003470:Culture Media / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism* / Q000528:radiation effects; D009154:Mutation
chemical_list: D000085:Acetates; D003470:Culture Media