Revival of saprotrophic and mycorrhizal basidiomycete cultures after 30 years in cold storage in sterile water.

Vegetatively colonized agar cores of 54 basidiomycete fungal isolates were stored at 5 °C in tubes of sterile distilled water without manipulation for 30 years. The cultures represented 28 isolates of saprotrophic fungi and 26 isolates of mycorrhizal fungi. These cultures came from a group of 57 fungal isolates that were determined to be viable after 20 years of cold-water storage. Overall, 47 of the 54 isolates (87%) grew vigorously when revived after storage for 30 years. Of the 28 saprotrophic fungal isolates, 26 revived (93%); of the 26 mycorrhizal fungal isolates, 21 revived (81%). Eight of 13 isolates (62%) of Laccaria were viable after 30 years, which was considerably less viable than what was found after 20 years for this genus of mycorrhizal fungi. However, a greater percentage of isolates of Laccaria bicolor (83%) were viable than isolates of Laccaria laccata (43%), suggesting that 30 years is approaching the maximum limit for storage in cold sterile water for certain species. Considering the original 135 fungal isolates that were stored in sterile cold water from which this set was derived, overall survival after 30 years of storage was 42%; however, saprotrophic fungi demonstrated considerably greater viability (70%) than mycorrhizal fungi (21%).

Comparison of effectiveness of wood decay fungi maintained by annual subculture on agar and stored in sterile water for 18 years.

Fourteen isolates of basidiomycete decay fungi (12 species) were maintained for 18 years on agar slants transferred annually and also stored as mycelium-agar cores under cold sterile water without subculture. Isolates stored by each method were evaluated for decay effectiveness using a standard laboratory accelerated soil-block decay test. Effectiveness was measured by mean percent mass loss of wood blocks. There was no significant difference (p < or = 0.05) in decay effectiveness between storage methods for 12 of the fungus isolates tested. For the 2 fungi that showed a significant difference in the amount of decay with respect to storage method, 1 fungus (Fomitopsis lilacinogilva) produced more decay by the strain maintained as an agar slant, while the other fungus (Trametes versicolor) produced more decay by the strain stored in sterile water. Results suggested that storage under sterile water is an easy and effective method to store isolates of decay fungi for long periods, but as with any microbial storage method, careful monitoring of isolates upon revival is necessary.