Many readers will be aware of the potential of living organisms to be sources of useful chemicals such as antibiotics, enzymes and so on — looking at medicinal properties alone, a search of records added to the CAB Abstracts database in the past 6 months finds 4241 indexed with ‘medicinal plants’ and 200 with ‘medicinal fungi’. Work is currently under way to investigate CABI’s own collection of fungi, the 28000 strains (of 6000 species) held in the Genetic Resources Collection, to see what compounds these species can provide.
The collection originated in the early 20th century as a collection of plant pathogenic fungi made by the Imperial Mycological Institute; the UK National Fungus Culture Collection (except for fungi that cause diseases in humans) was added to it in 1947, and new strains and species continue to be added. The fungi are kept alive, in some cases by storing them under mineral oil or growing them on agar plates, but the most important techniques are freeze-drying or cryopreservation in liquid nitrogen; these long-term methods ensure that the strains do not change, but they can easily be resuscitated and grown when necessary.
The most notable strain in the collection with respect to natural products is a line of Sir Alexander Fleming’s original penicillin-producing strain of Penicillium notatum, (now Penicillium chrysogenum) but in total there are 750 strains known to produce between them 442 metabolites that are important to the pharmaceutical sector. Among the many strains originally included in the collection for other reasons, it is likely that many will contain useful compounds; so far, more than 2000 have been biochemically characterized beyond the information that they were deposited with. Strains can be grown in different conditions to trigger the production of different chemicals.
CABI has partnerships with other organizations to identify more compounds and screen them for useful properties — high-throughput screening identifies potentially useful compounds which can then be investigated in more detail. The Royal Botanic Gardens at Kew are screening fungal endophyte extracts for activity against insects, fungi and bacteria; a joint project with Royal Holloway, University of London (featured on BBC Radio 4 in February) has recently been set up to screen the collection for antibiotics and nutraceuticals; and PharmaLinks are currently screening extracts against several of their targets, which include some important diseases for which there are at present few safe and effective drugs. The process is at an early stage, but initial results are very promising, so watch this space!
All development of compounds identified will of course be in accordance with the intellectual property provisions of the Convention on Biological Diversity.
[Acknowledgements to David Smith, CABI’s Director of Biological Resources, who supplied much of the information on which this blog entry is based].