FIG. 5.

Study of the sensitivity of different mutant strains to low pH. (A) Effect of inactivation of genes encoding proteins of the PKC pathway and upstream and downstream components, of BCK1 overactivation (BCK1-20 allele), as well as of hog1Δ on low-pH tolerance. Cells of the indicated strains and 10-fold serial dilutions thereof were spotted onto plates of YPD medium, YPD medium at pH 3.0, YPD medium plus 1 M sorbitol, and YPD medium at pH 3.0 plus 1 M sorbitol and incubated for 3 days at 30°C. (B) Effect of temperature-sensitive rho1 mutations on growth at low pH. Cells were spotted onto YPD medium as indicated above (A). The plates were incubated at 25°C or 37°C for 2.5 days. (C) Study of sensitivity of swi4Δ, swi6Δ, cch1Δ, and mid1Δ mutants to low pH. Cells were grown in YNB medium to an OD₆₀₀ of about 0.5, and the pH was decreased from 3.6 to 2.8. Cell viability was measured 6 h after the shock or not.