FIG 4.

H₂S-mediated bactericidal effect on oral streptococci requires iron. S. mitis (A) and S. oralis (B) in BHI broth were left untreated (control) or treated with DFO (0.5 mM) in the presence or absence of NaHS (2 mM) for 16 h, after which culture density was determined by taking optical density at 600 nm. The experiments were carried out 3 times, each time in triplicate. Data shown are the mean results obtained from 3 independent experiments. ***, P < 0.001.