Compared tolerance to osmotic stress in various microorganisms: Towards a survival prediction test

The osmotic tolerance of microbial cells of different microorganisms was investigated as a function of glycerol concentration and temperatures. Cells displayed specific sensitivity to dehydration in glycerol solutions. The viability of Gram‐negative strains ( Escherichia coli , Bradyrhizobium japonicum ), Gram‐positive strains ( Lactobacillus plantarum , L. bulgaricus ), and yeasts ( Saccharomyces cerevisiae , Candida utilis ) decreased with increasing osmotic pressure. For each strain, a characteristic osmotic pressure threshold causing a loss of 40% of the population at the growth temperature was determined: 26–40 MPa for E. coli , 15–25 MPa for B. japonicum , 7–15 MPa for L. bulgaricus , 40–133 MPa for L. plantarum , 50–100 MPa for S. cerevisiae , and 15–26 MPa for C. utilis . Because this threshold varies with temperature, it was possible to construct a diagram that could be helpful to the determination of the sensitivity of each strain to osmotic stress as a function of osmotic pressure and temperature. © 2005 Wiley Periodicals, Inc.