Cell density impacts onCandida glabratasurvival in hypo-osmotic stress

Candida glabrata cells suspended in water are under hypo-osmotic stress and undergo cell death in 1-2 days, unless they are at a density of more than 10(5 ) CFU mL(-1) . The dying cells exhibit FITC-annexin V staining, indicative of programmed cell death (apoptosis). In a higher cell density, cells are protected and survive at least for 4 days. Filtrates from cells at high density can protect those at lower density, indicating that cells release substances, amounting to c. 5 mg L(-1) of cell suspension, that protect each other against hypo-osmotic stress. In a concentrated form, the released materials can support growth, indicating that the protective material includes carbon and nitrogen sources, as well as vitamins that are required by C. glabrata for growth. We conclude that cell death from hypo-osmotic stress can be alleviated by small amounts of nutrients.