A new low-cost method for long-term preservation of filamentous fungi

Preservation of fungi for commercial and research purposes for a long time, is a very tedious task. Cryopreservation and lyophilization have been extensively used as long-term preservation techniques. Here, we introduced a novel method for long preservation and fast revival of filamentous fungi using sterile cotton balls (CB). A 16 fungal genera and 47 species represented by 135 strains have been preserved on cotton balls moistened with Potato Dextrose Agar (PDA) and incubated at 25 ± 2 °C until giving sufficient growth, then preserved at 17–20 °C for 36 months. The revival of the fungal growth on PDA was monitored every 6 months. A 135 fungal strains have been revived by the CB method with an overall revival rate of 100% after two years of long-term preservation. While, 76 strains were revived after three years of preservation and the revival rate was 59%. The viability or the mycelial morphology was unaffected by the new method even after three years of preservation. It is an easy, cost-effective, and convenient method for preservation of filamentous fungi for long period without contamination risk. We believe that the CB method is a very convenient method for a cheap delivery of filamentous fungi between research institutes.