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Growth of Stressed Strains of Four Non-O157 Shiga Toxin-Producing Escherichia coli Serogroups in Five Enrichment Broths
- Source :
- Journal of food protection. 78(11)
- Publication Year :
- 2015
-
Abstract
- The purpose of this study was to evaluate (i) the behavior of several strains of non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O103, O111, and O145) exposed to different stress conditions and (ii) the growth dynamics of stressed and nonstressed non-O157 STEC cells in five enrichment media. STEC strains were exposed to acid, cold, and freeze stresses. Lethal and sublethal injuries were determined by plating in parallel on selective and nonselective agar media. Freeze stress (8 days, 20°C) caused the most lethal (95.3% ± 2.5%) injury, as well as the most sublethal (89.1% ± 8.8%) injury in the surviving population. Growth of stressed and nonstressed pure cultures of non-O157 STEC on modified tryptic soy broth, buffered peptone water (BPW), BPW with sodium pyruvate, Brila, and STEC enrichment broth (SEB) was determined using total viable counts. To compare growth capacities, growth after 7 and 24 h of enrichment was measured; lag phases and maximum growth rates were also calculated. In general, growth on BPW resulted in a short lag phase followed by a high maximum growth rate during the enrichment of all tested strains when using all three stress types. Furthermore, BPW ensured the highest STEC count after 7 h of growth. Supplementing the medium with sodium pyruvate did not improve the growth dynamics. The two selective media, Brila and SEB, were less efficient than BPW, but Brila's enrichment performance was remarkably better than that of SEB. This study shows that irrespective of the effect of background flora, BPW is still recommended for resuscitation of non-O157 STEC.
- Subjects :
- education.field_of_study
food.ingredient
Shiga-Toxigenic Escherichia coli
Population
Biology
medicine.disease_cause
Immunomagnetic separation
Serogroup
Microbiology
Tryptic soy broth
Non o157
Culture Media
chemistry.chemical_compound
fluids and secretions
Sodium pyruvate
food
chemistry
medicine
Agar
education
Escherichia coli
Shiga toxin-producing Escherichia coli
Food Science
Subjects
Details
- ISSN :
- 19449097
- Volume :
- 78
- Issue :
- 11
- Database :
- OpenAIRE
- Journal :
- Journal of food protection
- Accession number :
- edsair.doi.dedup.....350f300dc2854750b175650bbdbd5c2e