title: Plant-adapted Escherichia coli show increased lettuce colonizing ability, resistance to oxidative stress and chemotactic response.
abstract: BACKGROUND
  Escherichia coli is a widespread gut commensal and often a versatile pathogen of public health concern. E. coli are also frequently found in different environments and/or alternative secondary hosts, such as plant tissues. The lifestyle of E. coli in plants is poorly understood and has potential implications for food safety.
  
  
  RESULTS
  This work shows that a human commensal strain of E. coli K12 readily colonizes lettuce seedlings and produces large microcolony-like cell aggregates in leaves, especially in young leaves, in proximity to the vascular tissue. Our observations strongly suggest that those cell aggregates arise from multiplication of single bacterial cells that reach those spots. We showed that E. coli isolated from colonized leaves progressively colonize lettuce seedlings to higher titers, suggesting a fast adaptation process. E. coli cells isolated from leaves presented a dramatic rise in tolerance to oxidative stress and became more chemotactic responsive towards lettuce leaf extracts. Mutant strains impaired in their chemotactic response were less efficient lettuce colonizers than the chemotactic isogenic strain. However, acclimation to oxidative stress and/or minimal medium alone failed to prime E. coli cells for enhanced lettuce colonization efficiency.
  
  
  CONCLUSIONS
  These findings help to understand the physiological adaptation during the alternative lifestyle of E. coli in/on plant tissues.
authors.affiliation: Instituto de Investigaciones en Biodiversidad y Biotecnología, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Buenos Aires, Argentina; Fundación para Investigaciones Biológicas Aplicadas, Mar del Plata, Buenos Aires, Argentina; Laboratorio Integrado de Microbiología Agrícola y de Alimentos, Facultad de Agronomía, Universidad Nacional del Centro de la Provincia de Buenos Aires, Azul, Buenos Aires, Argentina.
authors.forename: Maria de los Angeles
authors.initials: Mde L
authors.lastname: Dublan
authors.affiliation: Instituto de Investigaciones en Biodiversidad y Biotecnología, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Buenos Aires, Argentina; Fundación para Investigaciones Biológicas Aplicadas, Mar del Plata, Buenos Aires, Argentina.
authors.forename: Juan Cesar Federico
authors.initials: JC
authors.lastname: Ortiz-Marquez
authors.affiliation: Laboratorio Integrado de Microbiología Agrícola y de Alimentos, Facultad de Agronomía, Universidad Nacional del Centro de la Provincia de Buenos Aires, Azul, Buenos Aires, Argentina.
authors.forename: Lina
authors.initials: L
authors.lastname: Lett
authors.affiliation: Instituto de Investigaciones en Biodiversidad y Biotecnología, Consejo Nacional de Investigaciones Científicas y Técnicas, Mar del Plata, Buenos Aires, Argentina; Fundación para Investigaciones Biológicas Aplicadas, Mar del Plata, Buenos Aires, Argentina.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Curatti
mesh_terms: D002633:Chemotaxis; D004926:Escherichia coli / Q000502:physiology*; D054884:Host-Pathogen Interactions; D018545:Lactuca / Q000382:microbiology*; D018384:Oxidative Stress; D018515:Plant Leaves / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology