Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States and from a variety of seafood, including fish. Seawater represents a nutrient-limiting environment for V. parahaemolyticus. During its persistence in seawater, V. parahaemolyticus
is exposed to a variety of environmental stresses, including hyperosmolarity, fluctuations in temperature, and cold stress. The alternate sigma factor of RNA polymerase, designated σs (RpoS), encoded by the gene rpoS has been shown to play a major role in bacterial
adaptive responses to adverse environmental conditions. The present study was undertaken to investigate the role of rpoS in the survival of V. parahaemolyticus in seawater and fish. A V. parahaemolyticus rpoS mutant was constructed by the insertion of a chloramphenicol
acetyltransferase gene cassette within the rpoS gene, and the wild and mutant strains were assayed for their ability to survive in artificial seawater (ASW) at 6 and 18°C and in fish homogenate at 4 and 8°C. The survival of the rpoS mutant of V. parahaemolyticus
both in ASW and fish homogenate at either storage temperature was significantly (P < 0.05) lower than that of the wild strain. Further, the viability of V. parahaemolyticus, especially the mutant, was significantly reduced at lower storage temperatures of ASW and fish homogenate.
Results of this study indicate that rpoS potentially plays an important role in the survival of V. parahaemolyticus under conditions of cold stress and hyperosmolarity.
Document Type: Research Article
Department of Animal Science, Unit-40, University of Connecticut, 3636 Horsebarn Hill Road Extension, Storrs, Connecticut 06269, USA
Publication date: June 1, 2006
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