Significance of the dormant state in the persistence, interaction with growing plants and virulence of Shiga Toxin producing Escherichia coli

Shiga Toxin producing Escherichia coli (STEC) are potentially highly virulent and can cause illness at levels of 10 cells if ingested by a susceptible host. Manure is a significant source of STEC and consequently when applied to land there is an interval of 90 – 120 days before harvest to permit any pathogens to die-off. In field trials it has been demonstrated that STEC die-off rapidly within the first weeks of being incorporated into soil but a sub-population persist and can be recovered beyond 120 days. This led to speculation that there is a persistent sub-population of STEC that have enhanced tolerance to stress encountered in the field and possibly post-harvest. In the proposed study the persistent (dormant) state will be studied in STEC. Specifically, the culture conditions that induce the dormant state will be elucidated along with potential genes implicated. Studies will then determine the extent to which dormancy contributes to persistence in soil and resistance to sanitizers. Finally, the virulence of STEC in the dormant state will be determined. The main benefit of the research relates to providing data for risk assessment and also to develop novel methods to make STEC more susceptible to pre-along with post-harvest interventions.