Image showing Colonisation of spinach roots (magenta) by E. coli O157:H7 (green)

Human pathogenic bacteria are able to colonise plants and use them as alternative hosts.

Outbreaks of food-borne bacteria from consumption of fresh produce have increased in recent years, prompting an increase in research in the area. Although normally associated with animal hosts, human pathogenic bacteria are able to colonise plants are use them as alternative hosts. Work at The James Hutton Institute aims to understand the molecular basis to the interactions between the bacteria and their plant hosts. Our work has shown high levels of colonisation of both Escherichia coli O157:H7 and different Salmonella enterica serovars on a number of different fresh produce species (image above). However, it is evident that there are plant and bacterial-dependent differences that influence the colonisation outcome. While some bacteria promote a defensive response in the plants, other related bacteria do not, which raises the possibility that the bacteria are able to suppress host defences to facilitate persistence and colonisation, akin to plant-associated bacteria. The aim of our work is to identify and characterise effectors that may play such a role. The work fits directly into the effector consortia with the over-arching aim to elucidate the in planta role of microbial effectors.