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Viral mutation affecting bacteriophage phi 1 development in Bacillus subtilis 168
Abstract:
Bacillus subtilis bacteriophage phi 1m, a host-range variant, was isolated after mutagenesis of virulent bacteriophage phi 1. Unlike its wild-type antecedent, phi 1m could not form plaques on lawns of B subtilis 168 at 37 C, although it adsorbed to, penetrated, and killed this bacterium. Experiments conducted in liquid medium at 37 C showed that B. subtilis 168 cells allowed reduced levels of phi 1m development at low multiplicities of infection, whereas high multiplicity infections of this strain by the phage were abortive. Certain mutants, derived originally from B. subtilis 168, were observed to be permissive for phi 1m at 37 C; moreover, their permissive phenotype could be duplicated by growing wild-type B. subtilis 168 cells at temperatures above 47 C. Studies on phi 1m and host nucleic acid synthesis under nonpermissive conditions demonstrated that transciption and DNA synthesis proceeded up to 20 min after infection, after which time there was a cessation of all nucleic acid production. These observations are discussed with respect to other abortive bacteriophage infections in B. subtilis.
Insights
Bacillus subtilis bacteriophage phi 1m exhibits abortive infection in B. subtilis 168 at 37°C, halting nucleic acid synthesis. This phage-host interaction is temperature-dependent and influenced by infection multiplicity.
Area of Science:
- Microbiology
- Virology
- Bacteriology
Background:
- Bacillus subtilis bacteriophage phi 1m is a host-range variant derived from virulent bacteriophage phi 1.
- Bacteriophage phi 1m demonstrates an inability to form plaques on B. subtilis 168 lawns at 37°C, despite successful adsorption, penetration, and bacterial lysis.
Purpose of the Study:
- To investigate the mechanism of abortive infection of Bacillus subtilis 168 by bacteriophage phi 1m at 37°C.
- To elucidate the role of infection multiplicity and host cell temperature in the phi 1m-B. subtilis interaction.
Main Methods:
- Comparative plaque assays on B. subtilis 168 at 37°C.
- Liquid culture experiments to assess phage development at varying multiplicities of infection.
- Analysis of host and phage nucleic acid synthesis under nonpermissive conditions.
Main Results:
- Bacteriophage phi 1m infection of B. subtilis 168 at 37°C resulted in abortive development, particularly at high multiplicities of infection.
- Permissive infection was observed in specific B. subtilis 168 mutants and in wild-type cells grown above 47°C.
- Under nonpermissive conditions, transcription and DNA synthesis ceased approximately 20 minutes post-infection.
Conclusions:
- The abortive infection of B. subtilis 168 by phi 1m at 37°C is a complex phenomenon influenced by temperature and infection dose.
- Host cell physiology, potentially related to nucleic acid metabolism, plays a critical role in determining the outcome of bacteriophage infection.