Effect of oxygen and peroxide on Bacteroides fragilis cell and phage survival after treatment with DNA damaging agents

Bacteroides fragilis Bf-2 cells were more sensitive to far-UV radiation, N-methyl-N′-nitrosoguanidine, ethylmethane sulphonate, acriflavine and mitomycin C under aerobic conditions than under anaerobic conditions. The opposite effect was observed with H2O2-treated cells and exposure to O2 enhanced the survival of H2O2-treated cells. Pretreatment of cells with sublethal concentrations of H2O2 also increased the survival of H2O2-treated cells. Reactivation of UV- and X-irradiated and methylmethane sulphonate and H2O2-treated phage b-1 was induced by O2 and H2O2 in B. fragilis.