Persistence of Escherichia coli O157:H7 on the rhizosphere and phyllosphere of lettuce
Version of Record online: 22 SEP 2009
© 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology
Letters in Applied Microbiology
Volume 49, Issue 6, pages 784–790, December 2009
How to Cite
Mark Ibekwe, A., Grieve, C.M., Papiernik, S.K. and Yang, C.-H. (2009), Persistence of Escherichia coli O157:H7 on the rhizosphere and phyllosphere of lettuce. Letters in Applied Microbiology, 49: 784–790. doi: 10.1111/j.1472-765X.2009.02745.x
- Issue online: 10 NOV 2009
- Version of Record online: 22 SEP 2009
- 2009/0590: received 1 April 2009, revised 10 September 2009 and accepted 11 September 2009
- Escherichia coli O157:H7;
- real-time PCR;
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 stx1, stx2 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 × 103 CFU g−1 of starting DNA in rhizosphere and phyllosphere samples and about 102 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 stx1, stx2 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.