title: Cysteine requirements of naturally occurring cysteine auxotrophs of Escherichia coli.
abstract: The requirements for cysteine of naturally occurring cysteine auxotrophs of Escherichia coli were determined in a defined liquid medium. Maximal growth was obtained in the presence of cysteine concentrations between 20 and 250 mg/l. At concentrations below 20 mg/l growth of the auxotrophs, but not the prototrophic control, was suboptimal in this system. In the presence of cysteine concentrations in excess of 250 mg/l, growth of both auxotrophic and prototrophic E. coli was inhibited with lower growth yields, a decreased specific growth rate and an extended lag phase being observed. These effects were minimised in the presence of 2 mM L-leucine, L-isoleucine and L-valine.
authors.affiliation: Department of Microbiology, Prince of Wales Hospital, Sydney.
authors.forename: C J
authors.initials: CJ
authors.lastname: McIver
authors.forename: J W
authors.initials: JW
authors.lastname: Tapsall
mesh_terms: D003545:Cysteine / Q000378:metabolism*; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D009154:Mutation
chemical_list: D003545:Cysteine