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Fate of pGFP-bearing Escherichia coli O157:H7 in ground beef at 2 and 10 °C and effects of lactate, diacetate, and citrate.

Author(s) : AJJARAPU S., SHELEF L. A.

Type of article: Article

Summary

Although beef has been implicated in the largest outbreaks of Escherichia coli O157:H7 infection in the United States, studies on the fate of this pathogen have been limited. In the present study, a green fluorescent protein-expressing E. coli O157:H7 strain was used, and the stable marker allowed the authors to monitor the behaviour of the pathogen in ground beef stored aerobically from freshness to spoilage at 2 and 10 °C. The effects of sodium salts of lactate (SL) (0.9 and 1.8%) diacetate (SDA) (0.1 and 1.2%) and buffered citrate (SC) (1 and 2%) and combinations of SL and SDA were evaluated. SC had negligible antimicrobial activity, and SL delayed microbial growth, while SDA and SL plus SDA were most inhibitory to the total-aerobe population in the meat. At 2 °C, the initial numbers of E. coli O157:H7 (3 and 5 log(10) CFU/g) decreased by about 1 log(10) CFU/g when spoilage was manifest (lower than 7 log(10) CFU of total aerobes/g), irrespective of the treatment. Pathogen numbers did not decrease during storage at 10 °C. Results showed that the pathogen was resistant to the salts tested; thus, refrigerated meat contaminated with the pathogen remains hazardous.

Details

  • Original title: Fate of pGFP-bearing Escherichia coli O157:H7 in ground beef at 2 and 10 °C and effects of lactate, diacetate, and citrate.
  • Record ID : 2001-0334
  • Languages: English
  • Source: Appl. environ. Microbiol. - vol. 65 - n. 12
  • Publication date: 1999/12

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