Investigation of Ultralow Temperature for Fungal Cultures III. Viability and Growth Rate of Mycelial Cultures Following Cryogenic Storage

Abstract

Fungal strains (102 including Basidiomycetes, Ascomycetes, Fungi Imperfecti and Phycomycetes) remained viable by cryogenic preservation for 9 yr. Two strains survived for only 6 yr. Of the 2 suspending media used, dimethyl sulfoxide was significantly better than glycerol as a cryoprotectant for 8 strains. During storage, viability checks were performed. Variability was examined in relation to storage time, frozen-thawed cultures vs. first subcultures, mycelial plugs (discs), and vials. Variation in radial growth of colonies was a function of innate properties of an organism, and there was no evidence that variation was influenced by cryogenic conditions (freezing and storage). The proposed method of preservation was demonstrated to be suitable for long-term conservation of these strains and is presumably applicable to other mycelial cultures.