

@article {8132,
	title = {{Exposure of Escherichia coli {\{}O157:H7{\}} to soil, manure, or water influences its survival on plants and initiation of plant defense response}},
	journal = {Food Microbiology},
	volume = {38},
	year = {2014},
	pages = {87{\textendash}92},
	abstract = {This study evaluated whether growth medium or exposure conditions influence the production of capsular polysaccharides {\{}(CPS){\}} by Escherichia coli {\{}O157:H7,{\}} and whether changes in {\{}CPS{\}} impact plant defense responses, consequently affecting survival on plants. E.{\~{}}coli {\{}O157:H7{\}} grown in {\{}Luria{\textendash}Bertani{\}} {\{}(LB){\}} broth supplemented with manure extracts showed an approximately 58{\%} increase in {\{}CPS{\}} production compared to cells grown in {\{}LB{\}} medium alone. Levels of {\{}CPS{\}} were significantly higher for E.{\~{}}coli {\{}O157:H7{\}} cells exposed to soil or manure extracts as compared to the non-exposed {\{}LB{\}} cultured control. Arabidopsis thaliana plants expressing $\beta$-glucuronidase {\{}(GUS){\}} under the control of the $\beta$-1,3-glucanase {\{}(BGL2){\}} promoter were used to investigate whether E.{\~{}}coli {\{}O157:H7{\}} induces defense-related gene expression. Plants inoculated with E.{\~{}}coli {\{}O157:H7{\}} grown in {\{}LB{\}} containing manure extracts or cells exposed to manure extracts exhibited 3-fold and 2-fold lower {\{}GUS{\}} activity, respectively, suggesting a limited plant defense response compared to plants inoculated with cells grown in {\{}LB.{\}} On day 5 post inoculation the population of E.{\~{}}coli {\{}O157:H7{\}} grown in {\{}LB{\}} supplemented with manure on plants was significantly greater than the population of E.{\~{}}coli {\{}O157:H7{\}} grown in {\{}LB{\}} medium alone. E.{\~{}}coli {\{}O157:H7{\}} cells exposed to soil or manure exhibited greater survival on plants compared to {\{}LB-grown{\}} E.{\~{}}coli {\{}O157:H7.{\}} The results of this study underscore the need to consider medium composition and cultural conditions when conducting crop challenge studies.},
	doi = {10.1016/j.fm.2013.08.015},
	author = {Seo, Seungwook and Matthews, Karl R}
}
