[Differences in sensitivity of T3, T7, T4 and lambda phages to bleomycin and phleomycin]

Area of Science:

• Microbiology
• Molecular Biology
• Virology

Background:

• Bleomycin (BM) and phleomycin are chemically related antibiotics with DNA-damaging properties.
• Bacteriophages are viruses that infect bacteria and have distinct propagation mechanisms.
• Previous studies indicated varying sensitivities of biological systems to these antibiotics.

Purpose of the Study:

• To investigate the differential sensitivity of bacteriophages T3, T7, T4, and lambda to bleomycin and phleomycin.
• To explore the correlation between antibiotic resistance and DNA synthesis inhibition in both host bacteria and phages.
• To elucidate the mechanism behind the observed resistance of certain phages to bleomycin.

Main Methods:

• Comparative analysis of phage propagation inhibition by bleomycin and phleomycin at various concentrations.
• Assessment of host bacterial colony-forming capacity and DNA synthesis under antibiotic treatment.
• Evaluation of phage DNA synthesis inhibition in the presence of bleomycin.
• In vitro DNA degradation assays using bleomycin.

Main Results:

• Bacteriophages T3, T7, and T4 are resistant to high concentrations of bleomycin (up to 150 µg/ml).
• Phleomycin inhibits phage propagation in the order T4 < T3 < lambda, with 20 µg/ml phleomycin causing 95% inhibition of T3.
• Phage resistance to bleomycin correlates with minimal inhibition of phage DNA synthesis, while host bacterial DNA synthesis is rapidly halted.
• A discrepancy exists between the in vivo resistance of T3/T4 phages and the in vitro susceptibility of their DNA to bleomycin-induced fragmentation.

Conclusions:

• Bacteriophages T3, T7, and T4 exhibit significant resistance to bleomycin, a finding that contradicts the antibiotic's effect on host bacterial DNA.
• The mechanism underlying the insensitivity of T3, T7, and T4 phages to bleomycin remains undetermined.
• Differential effects of bleomycin and phleomycin on phage propagation highlight specific interactions with viral and bacterial genetic material.