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Persistence of Escherichia coli O157:H7 on the rhizosphere and phyllosphere of lettuce
Author(s) -
Mark Ibekwe A.,
Grieve C.M.,
Papiernik S.K.,
Yang C.H.
Publication year - 2009
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2009.02745.x
Subject(s) - phyllosphere , rhizosphere , salinity , library science , biology , ecology , computer science , genetics , bacteria
Aims: The major objective of this study was to determine the effects of low levels of Escherichia coli O157:H7 contamination on plant by monitoring the survival of the pathogen on the rhizosphere and leaf surfaces of lettuce during the growth process. Methods and Results: Real‐time PCR and plate counts were used to quantify the survival of E. coli O157:H7 in the rhizosphere and leaf surfaces after planting. Real‐time PCR assays were designed to amplify the stx 1, stx 2 and the eae genes of E. coli O157:H7. The detection limit for E. coli O157:H7 quantification by real‐time PCR was 2·4 × 10 3 CFU g −1 of starting DNA in rhizosphere and phyllosphere samples and about 10 2 CFU g −1 by plate count. The time for pathogens to reach detection limits on the leaf surface by plate counts was 7 days after planting in comparison with 21 days in the rhizosphere. However, real‐time PCR continued to detect stx 1, stx 2 and the eae genes throughout the experimental period. Conclusion: Escherichia coli O157:H7 survived throughout the growth period as was determined by real‐time PCR and by subsequent enrichment and immunomagnetic separation of edible part of plants. Significance and impact of the Study: The potential presence of human pathogens in vegetables grown in soils contaminated with E. coli O157:H7 is a serious problem to our national food supply as the pathogen may survive on the leaf surface as they come in contact with contaminated soil during germination.