Submitted to: Food Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/1/2010
Publication Date: 2/1/2011
Citation: Bhaduri, S. 2011. Effect of salt and acidic pH on the stability of virulence plasmid (pYV) in Yersinia enterocolitica and expression of virulence-associated characteristics. Food Microbiology. 28:171-173. Interpretive Summary: Yersinia enterocolitica, a bacterium which can cause severe intestinal distress when consumed in contaminated food, is of particular concern due its ability to grow at refrigeration temperatures. Disease is caused by those strains of bacteria which contain a virulence plasmid (pYV) of 70-kb. Prior research suggested that the capability of pYV to cause disease could be impaired by conditions similar to those that occur during the processing, packaging, and cooking of foods. This study established that the addition of salt and acidic conditions did not inactivate the disease-causing potential of Y. enterocolitica. This data, can inform regulatory agencies and industries to assume that any disease-causing Y. enterocolitica that withstand this treatment retain their ability to infect human.
Technical Abstract: The stability of the Yersinia enterocolitica virulence plasmid (pYV) under different NaCl concentrations and under acidic pH conditions was investigated. Exposure of five strains representing five serotypes of pYV-bearing virulent Y. enterocolitica to 0.5, 2 and 5% NaCl and under conditions of pH 4, 5, and 6 for 24 h at 28 deg C in the stationary phase did not lead to the loss of the virulence pYV from the surviving cells. At pH 3.0, the cells did not survive. Virulence assays using crystal violet binding, low calcium response, Congo red-uptake, hydrophobicity by latex particle agglutination, and autoagglutination, as well as pYV by the PCR analysis indicated that the surviving cells were still virulent.