Role of the alternative sigma factors {sigma}E and {sigma}S in survival of Salmonella enterica serovar Typhimurium during starvation, refrigeration and osmotic shock

1 Division of Veterinary Pathology, Infection and Immunity, School of Clinical Veterinary Science, University of Bristol, Langford, Bristol BS40 5DU, UK 2 Institute of Comparative Medicine, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, UK 3 Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK Correspondence Mark Roberts m.roberts{at}vet.gla.ac.uk The ability of Salmonella enterica serovar Typhimurium to survive environmental stress requires specific, coordinated, responses, which induce resistance to the stress condition. This study investigated the relative contribution of E and S , the sigma factors regulating extracytoplasmic and general stress response functions, respectively, to survival at low temperature and also in media of differing osmotic strength, conditions relevant to food preservation. To determine if low-temperature storage is a signal for E - and S -mediated survival, the ability of S . Typhimurium rpoE , rpoS and rpoE / rpoS mutants to survive in a saline starvation-survival model at a refrigeration temperature (4.5 °C) was examined. Under these conditions, the rpoE mutant was significantly ( P