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Growth and survival parameter estimates and relation
to RpoS levels in serotype O157:H7 and non‐O157 Shiga
toxin‐producing E scherichia coli
Author(s) -
Mand T.D.,
Döpfer D.,
Ingham B.,
Ané C.,
Kaspar C.W.
Publication year - 2013
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.12021
Subject(s) - rpos , escherichia coli , strain (injury) , microbiology and biotechnology , serotype , biology , enterobacteriaceae , shiga toxin , gompertz function , food science , gene expression , biochemistry , gene , promoter , anatomy , machine learning , computer science
Aims This study analysed the growth and survival of 18 strains of the six serotypes of non‐O157 S higa toxin‐producing E scherichia coli ( STEC ) (O26, O45, O103, O111, O121 and O145) most frequently implicated in human illness and compared them with E scherichia coli O157:H7 strain ATCC 43895. Methods and Results The data from growth in L uria– B ertani broth (LB)‐HCl ( pH 4·0, 4·5, 4·8), LB ‐lactate ( pH 4·5 and 4·8) and LB‐NaCl (5%, 7%) were fitted to modified G ompertz equations to enable quantitative comparisons across strains and media conditions. Serogroup O45 strains had growth rates that were equal to or significantly greater than the O157:H7 control strain in all growth conditions tested. The growth rate was independent from the maximum growth achieved, but three strains (103A, 121A and 45B) had significantly faster growth and greater maximum cell densities in LB‐NaCl 5% (strain 103A), LB‐HCl pH 4·0 (strain 121A) and LB‐NaCl 7% (strain 45B). Survival in LB‐HCl pH 3·0 of four strains (103C, 111B, 26B and 26C) was significantly greater and five strains (26A, 45A, 111A, 121A and 145A) were significantly reduced in comparison with the O157:H7 control strain. None of the STEC strains had greater survival in LB‐NaCl 12% than the O157:H7 control strain. A significant association was found between the exponential phase, but not stationary phase, RpoS level and survival of STEC. Conclusions Some STEC strains had growth or survival properties that exceeded those of the O157:H7 control strain, but none of the non‐O157 STEC had both significantly greater growth and survival properties. STEC survival was associated with the exponential‐phase RpoS level. Significance and Impact of the Study Results from this study define the variability in growth and survival of STEC strains that will be useful defining food product formulations and process interventions to control STEC . The presence of exponential phase σ s expands the significance of this alternative sigma factor.