Fig. 4

Growth of single cell isolates from five independent serial transfer experiments with S. cerevisiae, evolved for increased acetic acid tolerance (MUT1A, MUT2B, MUT3E, HAT1E and HAT2A) and one acetic acid tolerant strain obtained by UV mutagenesis and screening (UV-E3). Strains were grown in 96-well plates on SMG (pH 4.5) with 0–15 g/L acetic acid without prior adaptation to acetic acid. Final OD₆₆₀ of the six mutants (grey lines) and of reference strain CEN.PK113-7D (black lines) were measured after 5 days of incubation. Data points represent average and standard deviation from 32 replicates distributed over four independent experiments for every mutant and from 48 replicates for CEN.PK113-7D distributed over six independent experiments. At high acetic acid concentrations the relatively low fraction of growing cells coupled to stochasticity of the ability to grow, results in an increased number of wells without growth, and thereby in relatively high standard deviations of the average OD₆₆₀