FIG 3.
Growth and accumulation of AcP under stress conditions. (A) Growth of the wild-type, ΔackA, Δpta, and Δpta ΔackA strains was monitored in medium supplemented with 0.003% (vol/vol) H2O2 under relatively anaerobic conditions (see Materials and Methods for details) at 37°C using a Bioscreen C lab system. Data are expressed as the means of the results for three independent isolates grown in triplicate wells. (B) AcP accumulation of the wild-type, ΔackA, Δpta, and Δpta ΔackA strains was detected when cells were grown in the presence of 0.003% hydrogen peroxide. Cells were grown to the early exponential phase (OD600 = 0.4) in FMC medium, and cells were concurrently labeled with [32P]orthophosphate and subjected to the stress conditions for 1 h. AcP and Pi derived from S. mutans extracts by formic acid were spotted onto PEI-cellulose plates for 2D-TLC using first-dimension buffer (0.52 M LiCl and 1% [vol/vol] glacial acetic acid) and second-dimension buffer (1 M ammonium acetate and 0.35 M ammonium chloride). Arrows, the spot corresponding to AcP.