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Quantitative preservation of viability of Aspergillus fumigatus
D W Denning1, K V Clemons, D A Stevens
1Department of Medicine, Santa Clara Valley Medical Center, CA.
Abstract:
Quantitative preservation of the viability of two isolates of Aspergillus fumigatus was studied over a 15-month period of storage. Significant loss of viability occurred in isolates preserved at -70 degrees C in both phosphate-buffered saline with Tween (PBST) and 0.1% gelatin, immediately, and between 6 and 15 months. Storage in 10% and 25% dimethyl sulphoxide at -70 degrees C was successful up to 8 weeks with gradual loss of viability later. PBST at 4 degrees C or room temperature, or 10% glycerol at -70 degrees C maintained 100% viability of the cultures up to 6 months and 15 months, respectively. To preserve 100% viability, long-term storage of A. fumigatus is best done in 10% glycerol in PBST at -70 degrees C compared with the other methods tested.
Insights
Long-term storage of Aspergillus fumigatus (A. fumigatus) requires careful method selection. Optimal viability is maintained using 10% glycerol in phosphate-buffered saline with Tween (PBST) at -70°C.
Area of Science:
- Microbiology
- Mycology
- Preservation Science
Background:
- Aspergillus fumigatus is an important fungal pathogen.
- Maintaining viability of fungal cultures is crucial for research and diagnostics.
- Previous studies have explored various preservation methods with mixed success.
Purpose of the Study:
- To quantitatively assess the long-term viability of Aspergillus fumigatus isolates under different storage conditions.
- To identify the most effective cryopreservation method for maintaining A. fumigatus viability over a 15-month period.
Main Methods:
- Two isolates of A. fumigatus were stored for 15 months under various conditions.
- Tested storage media included phosphate-buffered saline with Tween (PBST), 0.1% gelatin, 10% and 25% dimethyl sulphoxide (DMSO), and 10% glycerol.
- Storage temperatures evaluated were -70°C, 4°C, and room temperature.
Main Results:
- Storage in PBST or 0.1% gelatin at -70°C resulted in significant viability loss immediately and between 6-15 months.
- Storage in 10% or 25% DMSO at -70°C maintained viability for up to 8 weeks, with subsequent gradual loss.
- PBST at 4°C or room temperature maintained viability up to 6 months.
- 10% glycerol at -70°C maintained 100% viability for 15 months.
Conclusions:
- Cryopreservation of A. fumigatus using PBST or gelatin at -70°C is not suitable for long-term storage.
- Dimethyl sulphoxide (DMSO) offers short-term preservation but leads to viability loss over time.
- Optimal long-term preservation of A. fumigatus viability (15 months) is achieved with 10% glycerol in PBST at -70°C.