Dataset Information

Effects of orange juice pH on survival, urease activity and DNA profiles of Yersinia enterocolitica and Yersinia pseudotuberculosis stored at 4 degree C.

ABSTRACT: The objective of this study was to determine the survival, growth rate and possible cellular adaptation mechanisms of Y. pseudotuberculosis and Y. enterocolitica in orange juice under different pH conditions. Yersinia was inoculated in orange juice with adjusted pH levels of 3.9, 4.0, and 7.0 and stored at 4 C for 3, 24, 72 and 168 hours (h). The inter-and intra-species variation is significant to the pH and time of incubation variables (p<0.05). At 3.9 pH the CFU (colony forming units) count decreased significantly.At pH 3.9 and 4.0, Y. enterocolitica and Y. pseudotuberculosis survived for at least 30 days and 15 days, respectively. Yersinia that survived under low pH in orange juice revealed enhanced urease activity within 12 h of incubation. The attachment gene (ail) could not be detected by PCR in Y. enterocolitica from undiluted sample incubated for 24 h or longer. Moreover, the FesI-restriction profile was altered when Y. pseudotuberculosis was stored at pH 4.0 orange juice for 7 days. These results indicate that Yersinia could survive and grow at low pH and the survival mechanisms could also enable the bacteria to survive the stomach pH barrier to cause enteric infection.

SUBMITTER: Abdela W

PROVIDER: S-EPMC3212038 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Effects of orange juice pH on survival, urease activity and DNA profiles of Yersinia enterocolitica and Yersinia pseudotuberculosis stored at 4 degree C.

Abdela Woubit W Graham Martha M Tsegaye Habtemariam H Temesgen Samuel S Yehualaeshet Teshome T

Journal of food safety 20111101 4

The objective of this study was to determine the survival, growth rate and possible cellular adaptation mechanisms of Y. pseudotuberculosis and Y. enterocolitica in orange juice under different pH conditions. Yersinia was inoculated in orange juice with adjusted pH levels of 3.9, 4.0, and 7.0 and stored at 4 C for 3, 24, 72 and 168 hours (h). The inter-and intra-species variation is significant to the pH and time of incubation variables (p<0.05). At 3.9 pH the CFU (colony forming units) count de ...[more]

PMID: 22081735

Similar Datasets

Project description:BackgroundYersinia enterocolitica, an important food- and water-borne enteric pathogen is represented by six biovars viz. 1A, 1B, 2, 3, 4 and 5. Despite the lack of recognized virulence determinants, some biovar 1A strains have been reported to produce disease symptoms resembling that produced by known pathogenic biovars (1B, 2-5). It is therefore imperative to identify determinants that might contribute to the pathogenicity of Y. enterocolitica biovar 1A strains. Y. enterocolitica invariably produces urease and the role of this enzyme in the virulence of biovar 1B and biovar 4 strains has been reported recently. The objective of this work was to study genetic organization of the urease (ure) gene complex of Y. enterocolitica biovar 1A, biochemical characterization of the urease, and the survival of these strains under acidic conditions in vitro.ResultsThe ure gene complex (ureABCEFGD) of Y. enterocolitica biovar 1A included three structural and four accessory genes, which were contiguous and was flanked by a urea transport (yut) gene on the 3' side. Differences were identified in ure gene complex of biovar 1A strain compared to biovar 1B and 4 strains. This included a smaller ureB gene and larger intergenic regions between the structural genes. The crude urease preparation exhibited optimal pH and temperature of 5.5 and 65 degrees C respectively, and Michaelis-Menten kinetics with a Km of 1.7 +/- 0.4 mM urea and Vmax of 7.29 +/- 0.42 micromol of ammonia released/min/mg protein. The urease activity was dependent on growth temperature and growth phase of Y. enterocolitica biovar 1A, and the presence of nickel in the medium. The molecular mass of the enzyme was > 545 kDa and an isoelectric point of 5.2. The number of viable Y. enterocolitica biovar 1A decreased significantly when incubated at pH 2.5 for 2 h. However, no such decrease was observed at this pH in the presence of urea.ConclusionsThe ure gene cluster of biovar 1A strains though similar to biovar 1B and 4 strains, exhibited important differences. The study also showed the ability of biovar 1A strains of Y. enterocolitica to survive at highly acidic pH in vitro in the presence of urea.

Project description:To infect a susceptible host, the gastrointestinal pathogen Yersinia enterocolitica must survive passage through the acid environment of the stomach. In this study, we showed that Y. enterocolitica serotype O8 survives buffered acidic conditions as low as pH 1.5 for long periods of time provided urea is available. Acid tolerance required an unusual cytoplasmically located urease that was activated 780-fold by low-pH conditions. Acid tolerance of Helicobacter species has also been attributed to urease activity, but in that case urease was not specifically activated by low-pH conditions. A ure mutant strain of Y. enterocolitica was constructed which was hypersensitive to acidic conditions when urea was available and, unlike the parental strain, was unable to grow when urea was the sole nitrogen source. Examination of other urease-producing gram-negative bacteria indicated that Morganella morganii survives in acidic conditions but Escherichia coli 1021, Klebsiella pneumoniae, Proteus mirabilis, Providencia stuartii, and Pseudomonas aeruginosa do not. Consistent with these results, biochemical evidence demonstrated that Y. enterocolitica and M. morganii ureases were activated in vitro by low pH with an unusually low activity optimum of pH 5.5. In whole cells activation occurred as medium values decreased below pH 3.0 for Y. enterocolitica and pH 5.5 for M. morganii, suggesting that in vivo activation occurs as a result of cytoplasmic acidification. DNA sequence analysis of portions of the M. morganii ure locus showed that the predicted primary structure of the enzyme structural subunits is most similar to those of Y. enterocolitica urease. One region of similarity between these two ureases located near the active site is distinct from most other ureases but is present in the urease of Lactobacillus fermentum. This region of similarity may be responsible for the unique properties of the Y. enterocolitica and M. morganii ureases since the L. fermentum urease also has been shown to have a low pH optimum for activity.

Dataset Information

Effects of orange juice pH on survival, urease activity and DNA profiles of Yersinia enterocolitica and Yersinia pseudotuberculosis stored at 4 degree C.

Publications

Effects of orange juice pH on survival, urease activity and DNA profiles of Yersinia enterocolitica and Yersinia pseudotuberculosis stored at 4 degree C.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets