Effect of Temperature on Saprophytic Cryptococci: Observations Relating to Wall Biosynthesis at Non-permissive Growth Temperatures

Summary: An attempt was made to define the basis of temperature-induced aberrant wall biosynthesis in Cryptococcus diffluens. A quantitative determination of the sulphydryl content of the cell surface of C. diffluens as an index of a protein disulphide reductase activity failed to reveal differences between cells cultured at permissive and non-permissive growth temperatures. Assays of β-1,3-exo-glucanase showed no abnormal activities which could be responsible for the temperature-induced aberrations. Cryptococcus diffluens excreted low molecular weight compounds non-specifically: UMP and AMP were the predominant nucleotides excreted. Uridine diphosphoglucose, a precursor of glucan biosynthesis, was accumulated and excreted by C. diffluens at non-permissive but not at permissive growth temperatures. A correlation exists between the rate of yeast multiplication at permissive temperatures and the extent of residual growth upon subsequent exposure to a non-permissive temperature.