CRYOGENIC LIGHT-MICROSCOPY AND THE DEVELOPMENT OF COOLING PROTOCOLS FOR THE CRYOPRESERVATION OF FILAMENTOUS FUNGI

One hundred and ninety five strains of fungi were observed during free zing and thawing using a cryogenic light microscope. There was no obvi ous link between taxonomic position and their morphological response t o freezing and thawing. The viability of seven of these strains was ex amined following freezing and thawing in the presence or absence of th e cryoprotectants glycerol and dimethyl sulphoxide. Intracellular ice and hyphal shrinkage were not necessarily lethal events, but in many c ases they affected the rate and quality of growth. Both cryoprotectant s reduced shrinkage, shifted the cooling rate where intracellular ice formed in many cases, and improved the recovery of strains. The result s presented aid the development of successful cryopreservation protoco ls.