A living collection is not a freezer of duplicates

A collection of living cultures preserves fungal strains in a state from which they can be grown again. The World Federation for Culture Collections describes such institutions as a global network for ex situ conservation of microbial diversity. The value does not lie in low temperature alone. A sample must have a verified identity, a number, a provenance, culture conditions, a legal status and a procedure for recovery.

Preservation may use freeze-drying, cryopreservation and other methods depending on the organism. Successive transfers on agar are convenient, but they increase the risk of changed characters, mix-ups and contamination. A professional collection therefore maintains master and working material, checks viability and purity, records every operation and plans for power failures. Duplicating the most important holdings at an independent location reduces the single point of loss.

Not every fungus can be grown without a partner. A biotrophic parasite, some mycorrhizal fungi or an organism known only from an environmental sequence may require a host, or conditions we cannot reproduce. A culture collection therefore does not replace habitat protection and a fungarium. It complements them, holding living, reproducible material for taxonomy, medicine, agriculture and research into metabolites.

Deposition must respect consent, rules on access to genetic resources, biosafety and distribution restrictions. A public catalogue should distinguish clearly between an available strain and a restricted one. The greatest threat is often not a freezer failure but unstable funding and the loss of competent staff. Ex situ conservation is a long-term scientific service, not a one-off sampling project.

A minimum security architecture

WFCC guidance says that wherever practical, each strain should be maintained by two different procedures; at least one should minimise genetic change through freeze-drying or cryopreservation in liquid nitrogen or a freezer at −140°C or below. Important strains and their documentation should be duplicated in another building, ideally at a separate site. When revived, a culture must be checked against the deposit using morphology, molecular profiles and purity records. A catalogue number alone does not guarantee current identity or viability. The 2010 guidance is a best-practice framework, not automatic certification of every collection. Ex-situ conservation covers only organisms maintainable in culture; it does not preserve the complete microbiome, host relationship or ongoing evolution in habitat.