Fig. 2.

RSV supplementation at the diauxic shift triggers oxidative stress. Cultures of Fig. 1 were analyzed for the presence of intracellular superoxide by the conversion of non-fluorescent dihydroethidium into fluorescent ethidium (Eth). (A) Summary graphs of the percentage of fluorescent/superoxide positive cells (% Eth) are reported. About 1000 cells for each sample (three technical replicates) in three independent experiments were examined. At the indicated time points, catalases/Sod enzymatic activities (B) and the levels of intracellular malondialdehyde (MDA) (C) were measured. All the measurements were normalized to the protein content. Day 0, diauxic shift. SD is indicated. Statistical significance as in Fig. 1 (*P≤0.05 and **P≤0.01).