The use of cryopreservation in the ex-situ conservation of fungi

Microbial genetic resources are collected and stored for many different reasons providing an organism base for future use and reference to support science and industry. There are almost 500 collections world-wide registered with the World Data Center for Microorganisms (WDCM). However, of the estimated 1.5 million fungi only 72000 strains have been described and less than 20% of these are held in collections. It is also evident that many microorganisms have only been isolated once as almost 50% of the species held by the WDCM collections are represented by one isolate only. Storage at ultra-low temperature has an essential role to play in securing these organisms for sustainable use. A two step method of cooling was initially employed which approximated -1 degrees C min(-1). Improved viability and stability was achieved by using linear cooling rates determined by cryogenic light microscopy.