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Comparative studies on generalized transducing bacteriophages of Proteus mirabilis, phim and pi1
Abstract:
Comparative studies were made on the generalized transducing bacteriophages of Proteus mirabilis phim (Nakaya and Rownd), pi1(Böhme), and a clear plaque-forming mutant phim-c, derived from phim. Electron microscopic observations revealed that these phages were morphologically identical, indicating that they belonged to the group C of Bradley's classification, or to the type C1 of Ackermann's classification. Phages phim and pi1 formed characteristic turbid plaques different from each other, and the plaques of pi1 were smaller in size than those of phim. The plaques of phage phim-c were clear and also were the largest in size among those studied. Average latent periods of phim and pi1 were 70 and 60 min, respectively. Average burst size was found to be 30 and 10 plaque-forming units per infected cell for phim and pi1, respectively. It was confirmed by cross neutralization tests that phim and pi1 differed serologically from each other. The host range of the two phages also differed, and phage phim was more sensitive to heat than pi1. These results indicate that phages phim and pi1 are different types of phages. Majority of the properties of phage phim-c were nearly identical with those of phage phim except that the multiplication of phim-c was more strongly inhibited by methylene blue than that of phim and pi1. Phage phim-c is considered to be a clear mutant of phim.
Insights
Comparative studies on Proteus mirabilis bacteriophages phim and pi1 revealed distinct characteristics, including plaque formation, latent periods, and host range. Phage phim-c, a clear plaque mutant, shared most properties with phim.
Area of Science:
- Microbiology
- Virology
- Bacteriology
Background:
- Bacteriophages are viruses that infect bacteria.
- Generalized transducing bacteriophages are capable of transferring bacterial DNA between cells.
- Proteus mirabilis bacteriophages phim and pi1 are important subjects for studying phage-host interactions.
Purpose of the Study:
- To conduct comparative studies on the generalized transducing bacteriophages of Proteus mirabilis: phim, pi1, and a clear plaque mutant phim-c.
- To characterize and differentiate these bacteriophages based on morphological, physiological, and serological properties.
Main Methods:
- Electron microscopy for morphological analysis.
- Plaque assays to assess plaque characteristics (turbidity, size).
- Latent period and burst size determination.
- Cross-neutralization tests for serological comparison.
- Host range determination.
- Sensitivity assays using methylene blue.
Main Results:
- Phages phim, pi1, and phim-c were morphologically identical, belonging to Bradley's group C / Ackermann's type C1.
- Phages phim and pi1 exhibited distinct turbid plaque morphologies and sizes, with pi1 plaques being smaller.
- Phage phim-c formed clear, large plaques.
- Significant differences were observed in latent periods (phim: 70 min, pi1: 60 min) and burst sizes (phim: 30 PFU/cell, pi1: 10 PFU/cell).
- Cross-neutralization tests confirmed serological differences between phim and pi1.
- Host ranges differed, and phim was more heat-sensitive than pi1.
- Phage phim-c showed similar properties to phim, except for stronger inhibition of multiplication by methylene blue.
Conclusions:
- Phages phim and pi1 are distinct types of bacteriophages based on their biological and serological properties.
- Phage phim-c is a clear plaque mutant of phage phim, with minor differences in sensitivity to methylene blue.