Figure 5. Environmental alkalinization by C. glabrata.

(A) Viable, but not heat killed C. glabrata were able to alkalinize an acidic medium when grown with amino acids as the sole carbon and nitrogen source. 1×10⁶ C. glabrata cells/ml were inoculated in a 24 well plate with liquid YNB medium with 1% casamino acids and 20 mg/l phenol red. Within 24 h the pH rose from pH 4 to a pH above 6.8, as indicated by a color change of the pH indicator. The mutant put3Δ was incapable of alkalinization, the mutant bcy1Δ showed an intermediate phenotype of reduced alkalinization. (B) Similar results were obtained when using a solid medium (YNB with 1% casamino acids, 2% agar and 0.01% bromocresol green).