Comparative studies with tox plus and tox minus corynebacteriophages

Area of Science:

• Microbiology
• Virology
• Genetics

Background:

• Corynebacteriophages are viruses that infect bacteria, including those causing diphtheria.
• Understanding phage characteristics is crucial for studying bacterial genetics and toxin production.

Purpose of the Study:

• To compare nine inducible temperate corynebacteriophages.
• To correlate virion morphology and genetic recombination ability with other phage properties.
• To analyze the distribution of the toxin-producing gene (tox+) marker.

Main Methods:

• Determined immunity specificity, host range, and plaque morphology for each phage.
• Characterized representative phages by virion morphology, recombination with beta(tox+), latent period, burst size, and serum neutralization.
• Analyzed the distribution of the tox+ genetic marker.

Main Results:

• Phages grouped into five immunity specificity types and showed diverse host ranges and plaque morphologies.
• Only phages with similar virion morphology to beta(tox+) could genetically recombine with it.
• The tox+ marker was found in genetically unrelated phages with different morphologies, including beta(tox+) and delta(tox+).

Conclusions:

• Virion morphology is a key factor for genetic recombination in these corynebacteriophages.
• Characteristics like immunity specificity and host range are less reliable for determining phage relatedness.
• The presence of tox+ in unrelated phages raises questions about its origin and the evolution of toxin synthesis in corynebacteria.