Challenge of yeast cells with exogenous H2O2
Cultures were grown to mind-exponential phase (12 h ; OD600=0.5) under the conditions described above. Cells were washed twice with 100 mM potassium phosphate buffer, pH 7.4 (KPi), collected by centrifugation at 2000 g for 10 min at 25 ⁰C and divided in two fractions. The fractions were resuspended in the YPD from the original culture or in KPi, and challenged with H2O2 at 30 ⁰C for 1.5h with shaking at 225 rpm and a flask-to=medium volume ratio of 1:5 Following the challenge, the cultures were serially diluted, plated on YPD ager and incubated at 30 ⁰C for 2 days. Cell viability was determined by counting the total colony forming units (cfu) in H2O2 – challenged and untreated cultures.