Virulence Plasmid (pYV)‎-Associated Expression of Phenotypic Virulent Determinants in Pathogenic Yersinia Species : A Convenient Method for Monitoring the Presence of pYV under Culture Conditions and Its Application for IsolationDetection of Yersinia pestis in Food

Abstract EN

In Yersinia pestis, Y.

pseudotuberculosis, and Y.

enterocolitica, phenotypic expression of virulence plasmid (pYV: 70-kb)-associated genetic determinants may include low-calcium response (Lcr, pinpoint colony, size = 0.36 mm), colony morphology (size = 1.13 mm), crystal violet (CV) binding (dark-violet colony), Congo Red (CR) uptake (red pinpoint colony, size = 0.36 mm), autoagglutination (AA = cells agglutinate), and hydrophobicity (HP = clumping of cells).

Y.

pseudotuberculosis is chromosomally closely related to Y.

pestis; whereas, Y.

enterocolitica is chromosomally more distantly related to Y.

pestis and Y.

pseudotuberculosis.

All three species demonstrate Lcr, CV binding, and CR uptake.

The colony morphology/size, AA, and HP characteristics are expressed in both Y.

pseudotuberculosis and Y.

enterocolitica but not in Y.

pestis.

Congo red uptake in Y.

pestis was demonstrated only on calcium-deficient CR magnesium oxalate tryptic soy agar (CR-MOX), whereas this phenotype was expressed on both CR-MOX and low-calcium agarose media in Y.

pseudotuberculosis and Y.

enterocolitica.

These phenotypes were detectable at 37°C within 24 h in Y.

enterocolitica and Y.

pseudotuberculosis but did not appear until 48 h in Y.

pestis due to its slower growth rate at 37°C.

The pYV is unstable (i.e., easily lost under a variety of culture conditions) in all three species but is more unstable in Y.

pestis.

The specific CR uptake by Y.

pestis in CR-MOX and the delayed time interval to express Lcr and CR uptake provide a means to differentiate Y.

pestis from Y.

enterocolitica and Y.

pseudotuberculosis.

These differences in pYV expression in Y.

pestis can be used for its isolation and detection in food.