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Bacteriophage and bacteriophage-like structures carried by Bacillus medusa and their effect on sporulation
Abstract:
Bacillus medusa was found to carry three phages or phagelike structures named phi med-1, phi med-2, and phi med-3. phi med-1 is a minute, 25-nm-diameter particle without a tail. It was extracted from the sporulation lysate of a phi med-2-minus strain of B. medusa and purified by differential centrifugation. The nucleic acid from this structure was shown to be orcinol positive, alkali sensitive, RNase sensitive, and DNase resistant. An RNase-resistant core of nucleic acid was not found, indicating that it was single-stranded RNA. A host strain has not yet been found for phi med-1. Phage phi med-3 was induced with mitomycin C or UV light and consisted of empty heads of 57 nm in diameter, whereas phi med-2 induced with mitomycin was a phage of 60-nm head diameter and 220-nm tail length. The sporulation sequence proceeded faster in those mutants lacking phi med-2, and when the phage was reintroduced to B. medusa the extended wild-type sporulation sequence was observed. B. thuringiensis var. schwetzova was sensitive to phi med-2 and yielded small turbid plaques. B. medusa produced small numbers of phi med-2 during growth. The other phage may be produced at the same time but were not detected. Phi med-1 was found in sporulating cells by electron microscopy techniques. Its release from these was demonstrated by both electron microscopy techniques and a radioactive assay. It appears to participate in the formation of a surface layer on the parasporal inclusion of B. medusa.
Insights
Bacillus medusa harbors three phages: phi med-1 (single-stranded RNA), phi med-2, and phi med-3. Phi med-2 influences sporulation and infects other bacteria.
Area of Science:
- Microbiology
- Bacteriology
- Virology
Background:
- Bacillus medusa harbors several bacteriophages.
- These phages, phi med-1, phi med-2, and phi med-3, were investigated.
- The role of these phages in the host bacterium's life cycle is unclear.
Purpose of the Study:
- To characterize the three phages found in Bacillus medusa.
- To determine the nature of phi med-1's nucleic acid.
- To investigate the role of phi med-2 in Bacillus medusa sporulation.
Main Methods:
- Electron microscopy was used to visualize and measure phage particles.
- Differential centrifugation was employed for purification.
- Nucleic acid analysis involved RNase and DNase sensitivity tests.
- Mitomycin C and UV light were used for phage induction.
- Bacterial growth assays and plaque assays were performed.
Main Results:
- Phi med-1 is a 25-nm particle with single-stranded RNA, lacking a tail.
- Phi med-3 consists of 57-nm empty heads.
- Phi med-2 has a 60-nm head and a 220-nm tail.
- Mutants lacking phi med-2 exhibited accelerated sporulation.
- Reintroduction of phi med-2 restored the wild-type sporulation sequence.
- Phi med-2 infected Bacillus thuringiensis var. schwetzova.
- Phi med-1 is involved in forming a surface layer on parasporal inclusions.
Conclusions:
- Bacillus medusa harbors three distinct bacteriophages with different structures and nucleic acids.
- Phi med-2 plays a significant role in regulating Bacillus medusa sporulation.
- Phi med-1 is a novel ssRNA phage associated with parasporal inclusion formation.