DNA-mediated prophage induction in Bacillus subtilis lysogenic for phi 105c4

Area of Science:

• Microbiology
• Molecular Biology
• Bacteriology

Background:

• Prophage induction is a critical process in bacteriophage biology.
• Bacillus subtilis lysogenic strains can be induced to produce phage under specific conditions.
• Understanding prophage induction mechanisms is key to controlling phage-host interactions.

Purpose of the Study:

• To investigate the induction of prophage in Bacillus subtilis by specific bacterial DNAs.
• To determine the influence of DNA source and form on the efficiency of prophage induction.
• To elucidate the mechanism underlying DNA-mediated prophage induction.

Main Methods:

• Lysogenic Bacillus subtilis strains (phi105c4) were grown to competence.
• Exposure to specific bacterial DNAs (B. subtilis, B. licheniformis) and phi105 DNA variants.
• Measurement of phage production over time and bacterial transformation assays.
• Comparison of induction levels based on DNA concentration and source.

Main Results:

• Bacterial DNA exposure induced prophage production in B. subtilis, mimicking mitomycin C induction.
• Induction efficiency varied significantly with DNA source, with B. subtilis DNA being more active than B. licheniformis DNA.
• Different forms of phi105 DNA exhibited distinct inducing activities, with lysogen DNA showing higher activity than phage particle DNA.
• Inducing activity correlated with the DNA's ability to transform bacterial auxotrophic markers.

Conclusions:

• Prophage induction in B. subtilis can be triggered by exogenous bacterial DNA.
• The source and structural integrity of DNA play crucial roles in modulating induction efficiency.
• A recombination-based mechanism at the prophage insertion site is proposed to explain the observed induction phenomena.