Cell density impacts on Candida glabrata survival in hypo-osmotic stress

Abstract

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 105CFU 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. Low concentrations of yeast in water die quickly but at higher densities cells efficiently help the population to survive through the release of small amounts of nutrients that appear critical to this quorum protection. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.