To examine adaptation, cells grown for 12 h in YPD as described above, were pre-challenged with 2mM H2O2 at 30 ⁰C for 1h, switched to KPi and challenged with 2 mM H2O2 30 ⁰C for 1.5 h (YPD/KPi column). Alternatively, cells grown for 12 h in YPD were switched to KPi and both pre-adapted and challenged in this medium without buffer exchange (KPi column). The viability of pre-adapted cells is expressed as the ratio of the cfu following the lethal H2O2 challenge divided by the cfu following the 1 h pre-adaptation. Average viabilities ±SD of three independent cultures (n=3) are presented.