Nonsense mutation in spr1178 and reduced accumulation of reactive oxygen species induced by bactericidal antibiotics. Drug-induced reactive oxygen species accumulation in S. pneumoniae. The DCF-DA fluorescence signals of the S. pneumoniae R6SmR, 2x2b1a-M2 (green bars) and R6SmR, 2x2b1a, spr1178-M2 (yellow bars) transformants following exposure to (a) 0.1 μg/ml penicillin, (b) 4.0 μg/ml ciprofloxacin, (c) 400.0 μg/ml kanamycin, (d) 6.0 μg/ml chloramphenicol, and (e) 0.25 μg/ml tetracycline were measured prior to antibiotic exposure (time zero) and 1 hour, 2 hours, and 3 hours following addition of the antibiotics. The DCF-DA fluorescence signals of the S. pneumoniae R6SmR, 2x2b1a-M2 (blue bars) and R6SmR, 2x2b1a, spr1178-M2 (orange bars) transformants untreated cultures measured at each time point are indicated as control. Results are the average of at least three independent experiments. RFU, relative fluorescence units.
Fani et al. Genome Biology 2011 12:R115 doi:10.1186/gb-2011-12-11-r115