Fate in sewage of a recombinant Escherichia coli K-12 strain used in the commercial production of bovine somatotropin.
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.
Heitkamp
M A
MA
Environmental Sciences Center, Monsanto Company, St. Louis, MO 63167.
Kane
J F
JF
Morris
P J
PJ
Bianchini
M
M
Hale
M D
MD
Bogosian
G
G
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
D012722:Sewage; D013006:Growth Hormone