title: Exposure of Escherichia coli O157:H7 to soil, manure, or water influences its survival on plants and initiation of plant defense response.
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-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 β-glucuronidase (GUS) under the control of the β-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.
authors.affiliation: Department of Food Science, Rutgers University, New Brunswick, NJ 08901, United States.
authors.forename: Seungwook
authors.initials: S
authors.lastname: Seo
authors.forename: Karl R
authors.initials: KR
authors.lastname: Matthews
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000276:immunology; D016667:Bacterial Capsules / Q000378:metabolism; D019453:Escherichia coli O157 / Q000254:growth & development* / Q000378:metabolism; D008372:Manure / Q000032:analysis* / Q000382:microbiology; D050296:Microbial Viability; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D008372:Manure; D012987:Soil; D014867:Water
keywords: Capsular polysaccharides; Escherichia coli O157:H7; Plant challenge; Produce