Fate in sewage of a recombinant Escherichia coli K-12 strain used in the commercial production of bovine somatotropin

• Published in: Journal of industrial microbiology Vol. 11; no. 4; p. 243
• Main Authors: Heitkamp, M A, Kane, J F, Morris, P J, Bianchini, M, Hale, M D, Bogosian, G
• Format: Journal Article
• Language: English
• Published: England 01-07-1993
• Subjects: Colony Count, Microbial; Escherichia coli - growth & development; Escherichia coli - metabolism; Growth Hormone - biosynthesis; Sewage; Technology, Pharmaceutical; Water Microbiology
• ISSN: 0169-4146
• DOI: 10.1007/BF01569597

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.