title: Fate in sewage of a recombinant Escherichia coli K-12 strain used in the commercial production of bovine somatotropin.
abstract: The fate of a derivative of Escherichia coli strain W3110G [pBGH1], a strain used for production of bovine somatotropin, was examined in semi-continuous activated sludge (SCAS) units. A nalidixic acid-resistant derivative of W3110G [pBGH1], strain LBB270 [pBGH1], was used to facilitate tracking. SCAS units (300 ml) containing municipal mixed liquor were operated on a daily cycle of 23 h aeration and 1 h setting followed by decanting of clear supernatant (175 ml) and refilling with fresh primary effluent. SCAS units were inoculated with two concentrations of E. coli LBB270 [pBGH1] and operated for 200 h. Viable levels of E. coli LBB270 [pBGH1] were measured daily in aerated mixed liquor and decanted supernatant. Viable counts in the mixed liquor decreased from 10,000- to 100,000-fold in less than 200 h. Losses of E. coli LBB270 [pBGH1] in decanted supernatants accounted for less than 2-fold of the total losses observed in the SCAS units. The E. coli LBB270 [pBGH1] was not evenly distributed in the mixed liquor, but became preferentially associated with the settleable floc. These results show that E. coli LBB270 [pBGH1] was unable to survive in municipal sludge even when inoculated at concentrations greater than, or comparable to, levels of indigenous microorganisms.
authors.affiliation: Environmental Sciences Center, Monsanto Company, St. Louis, MO 63167.
authors.forename: M A
authors.initials: MA
authors.lastname: Heitkamp
authors.forename: J F
authors.initials: JF
authors.lastname: Kane
authors.forename: P J
authors.initials: PJ
authors.lastname: Morris
authors.forename: M
authors.initials: M
authors.lastname: Bianchini
authors.forename: M D
authors.initials: MD
authors.lastname: Hale
authors.forename: G
authors.initials: G
authors.lastname: Bogosian
mesh_terms: D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D013006:Growth Hormone / Q000096:biosynthesis; D012722:Sewage; D013678:Technology, Pharmaceutical; D014871:Water Microbiology
chemical_list: D012722:Sewage; D013006:Growth Hormone