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Scanning electron microscopic study of virulent Yersinia pestis and Yersinia pseudotuberculosis type 1
Abstract:
Virulent Yersinia pestis was grown on heart infusion blood agar and examined by scanning electron microscopy, exposing the fraction 1 envelope antigen on cell surfaces as a lumpy coating that spilled into the surrounding milieu. The amount of antigen depended on both the duration and temperature of incubation. Comparison of the cultures grown at 37 degrees C for 24, 48, and 72 h with those grown at 22 degrees C for identical periods demonstrated that the antigen increased in amount with the length of incubation, and that the overall production of antigen was much greater of 37 degrees C than at 22 degrees C. These experiments visually confirmed the findings of our previous immunological studies. Moreover, we established that the closely related, virulent organism Y. pseudotuberculosis bears no such antigenic coating at any temperature or incubation period. In addition, the emergence of multiple flagella was noted when Y. pseudotuberculosis was grown at 22 degrees C in a liquid medium, whereas Y. pestis remained without these organelles. These observations preceptibly corroborated the absence of fraction 1 envelope antigen and the presence of flagella, respectively, for distinguishing Y. pseudotuberculosis from Y. pestis.
Insights
Virulent Yersinia pestis produces a distinct fraction 1 envelope antigen coating, with production increasing at higher temperatures and longer incubation. This antigen is absent in Yersinia pseudotuberculosis, which exhibits flagella.
Area of Science:
- Microbiology
- Immunology
- Cell Biology
Background:
- Yersinia pestis is a virulent bacterium responsible for plague.
- Understanding Yersinia pestis surface antigens is crucial for diagnostics and therapeutics.
- Fraction 1 (F1) antigen is a key virulence factor of Yersinia pestis.
Purpose of the Study:
- To visually characterize the fraction 1 envelope antigen of Yersinia pestis using scanning electron microscopy.
- To investigate the influence of incubation temperature and duration on F1 antigen production.
- To differentiate Yersinia pestis from the closely related Yersinia pseudotuberculosis based on surface antigen expression.
Main Methods:
- Culturing virulent Yersinia pestis and Yersinia pseudotuberculosis on heart infusion blood agar.
- Utilizing scanning electron microscopy (SEM) for high-resolution visualization of bacterial surface structures.
- Comparing antigen expression and morphological features under varying incubation conditions (temperature and time).
Main Results:
- SEM revealed a lumpy coating of fraction 1 envelope antigen on Yersinia pestis surfaces.
- F1 antigen production increased with incubation duration and was significantly greater at 37°C compared to 22°C.
- Yersinia pseudotuberculosis lacked the F1 antigenic coating and exhibited multiple flagella at 22°C, unlike Yersinia pestis.
Conclusions:
- Scanning electron microscopy visually confirmed the presence and characteristics of the Yersinia pestis fraction 1 envelope antigen.
- Incubation temperature and duration significantly impact the expression of F1 antigen in Yersinia pestis.
- The presence of flagella in Yersinia pseudotuberculosis and their absence in Yersinia pestis, along with the F1 antigen difference, provides distinct markers for differentiation.
