The effect of growth phase, cryoprotectants and freezing rates on the survival of selected micro-organisms during freezing and thawing

The effect of growth phase of cells, cryoprotectant agents and freezing rate on the survival of selected micro-organisms (Bacillus cereus, Lactobacillus plantarum, Escherichia coli, Pseudomonas fluorescens, Saccharomyces cerevisiae, Kluyveromyces lactis, Candida utilis, Mucor racemosus, Aspergillus niger) during freezing and thawing was studied. In cases where significant differences were observed stationary phase cells always survived better than exponential phase ones, while of the two cryoprotectant agents studied, horse serum + inositol was always superior to skimmed milk powder + inositol. The effect of freezing rate was different among the studied micro-organisms.