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Comparison of Vibrio parahaemolyticus grown in estuarine water and rich medium
1Center for Environmental and Estuarine Studies, University of Maryland, Cambridge 21613.
Abstract:
Cell envelope composition and selected physiological traits of Vibrio parahaemolyticus were studied in regard to the Kanagawa phenomenon and growth conditions. Cell envelopes were prepared from cells cultured in Proteose Peptone-beef extract (Difco Laboratories, Detroit, Mich.) medium or filtered estuarine water. Protein, phospholipid, and lipopolysaccharide contents varied with culture conditions. The phospholipids present in the cell envelopes were identified as phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. Phosphatidylethanolamine decreased and phosphatidylglycerol increased in cells grown in estuarine water. Profiles of proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated numerous protein species, with four to six predominant proteins ranging from 26,000 to 120,000 in molecular weight. The profile of V. parahaemolyticus cell envelope proteins was unique and might be useful in the identification of the organism. Alkaline phosphatase activity was slightly higher in Kanagawa-negative strains and was higher in cells grown in estuarine water than in cells grown in rich laboratory medium. The DNA levels in estuarine water-grown cells increased, while RNA levels and cell volume decreased. Bacteriophage sensitivity typing demonstrated a close intraspecies relationship. Results indicated that Kanagawa-positive and -negative strains were closely related, but they could be grouped separately and may have undergone starvation-related physiological changes when cultured in estuarine water.
Insights
Vibrio parahaemolyticus cell envelope composition and physiology change with growth conditions. These changes, including protein profiles and alkaline phosphatase activity, may distinguish Kanagawa-positive and -negative strains.
Area of Science:
- Microbiology
- Bacterial Physiology
- Molecular Biology
Background:
- Vibrio parahaemolyticus is a significant foodborne pathogen.
- The Kanagawa phenomenon is a key virulence marker for V. parahaemolyticus.
- Understanding V. parahaemolyticus physiology is crucial for controlling its spread.
Purpose of the Study:
- To investigate the cell envelope composition and physiological traits of Vibrio parahaemolyticus.
- To determine how growth conditions affect these characteristics in relation to the Kanagawa phenomenon.
- To explore potential markers for bacterial identification and strain differentiation.
Main Methods:
- Culturing V. parahaemolyticus in different media (Proteose Peptone-beef extract and estuarine water).
- Analyzing cell envelope components: protein, phospholipid, and lipopolysaccharide.
- Utilizing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiling.
- Measuring alkaline phosphatase activity and quantifying DNA/RNA levels.
- Performing bacteriophage sensitivity typing.
Main Results:
- Cell envelope protein, phospholipid, and lipopolysaccharide content varied with culture conditions.
- Specific phospholipid changes (decrease in phosphatidylethanolamine, increase in phosphatidylglycerol) were observed in estuarine water.
- SDS-PAGE revealed unique V. parahaemolyticus cell envelope protein profiles.
- Alkaline phosphatase activity was higher in Kanagawa-negative strains and in cells grown in estuarine water.
- Estuarine water-grown cells showed increased DNA, decreased RNA, and reduced cell volume.
- Bacteriophage typing indicated close intraspecies relationships, with potential grouping of Kanagawa-positive and -negative strains.
Conclusions:
- Growth conditions significantly alter Vibrio parahaemolyticus cell envelope composition and physiology.
- Unique protein profiles may aid in V. parahaemolyticus identification.
- Physiological changes observed in estuarine water suggest starvation-related adaptations.
- Kanagawa-positive and -negative strains are related but may exhibit distinct physiological responses.