Improved laboratory enrichment for enterohemorrhagic Escherichia coli by exposure to extremely acidic conditions - PubMed
Improved laboratory enrichment for enterohemorrhagic Escherichia coli by exposure to extremely acidic conditions
Michael A Grant. Appl Environ Microbiol. 2004 Feb.
Abstract
Analysis of food samples for E. coli O157:H7 using the standard U.S. Food and Drug Administration procedure is frequently complicated by overgrowth of nontarget microorganisms. A new procedure was developed for enrichment of enterohemorrhagic E. coli (EHEC) which utilizes exposure to pH 2.00 for 2 h. This procedure yielded larger populations of EHEC than the standard method by factors ranging from 2.7 to 7.7 and, when age-stressed cultures were used, by factors ranging from 2.7 to 11.5. Cultures of competing enterics were more effectively inhibited by the new enrichment protocol as well.
Figures
Growth of 10 strains of EHEC with either standard selective enrichment (S) or experimental acidification enrichment (A). Numbers 1 to 10 indicate strains 6424, 6443, 6457, M3579, G550637, M3039, 6321, 6347, 6396, and 178190, respectively.
Growth of 10 strains of age-stressed EHEC with either standard selective enrichment (S) or experimental acidification enrichment (A). Numbers 1 to 10 indicate strains 6424, 6443, 6457, M3579, G550637, M3039, 6321, 6347, 6396, and 178190, respectively.
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