Kathryn Wright

The colonisation of plants by human pathogenic bacteria

In collaboration with Nicola Holden, I investigaged the colonisation of young plants marketted as micro-herbs or microgreens, by Escherichia coli O157:H7 Sakai. Our work showed that if seeds germinate in the presence of low numbers of bacteria the young plants, e.g. basil, become extensively colonised by bacteria, most being present on the surface of the leaf tissue, but others within the leaf interior. This highlights that micro-herbs represent a potential hazard of contamination by food-borne pathogens, and to mitigate the risk, they should be considered in the same manner as sprouted seeds.

Once inside a leaf of a susceptible species for example Nicotiana benthamiana, E. coli Sakai can form large colonies showing characteristics of biofilm formation including production of curli and extracellular DNA.

In other species including spinach and lettuce, the bacteria can only be found in small numbers and do not appear to proliferate.  

I developed methods to study the colonisation of potato roots by Pectobacterium atrosepticum to identify the route of transfer to the developing plant and how this is influenced by free-living nematodes.

With colleagues I investigated the localisation of effectors secreted by potato cyst nematodes into their host.