A sample of human coronavirus (catalogue number 2008101v) will set you back £282 ($347). Browse on through the catalogue and it offers you the chance to buy a dose of Herpes simplex virus and cowpox for the same price or a sample of salmonella for £164. Ordering anthrax bacteria, perhaps understandably, is more expensive: £321. As Stephen Baker, a professor of microbiology at Cambridge, puts it, it is like reading “an Argos catalogue for micro-organisms”. Albeit one whose menu offers the option not to “Shop garden furniture” but to “Browse bacterial strains” or click on the “Chlamydia Biobank”.

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These are the online price lists for Britain’s culture collections—in the agar-plate-and-white-coat sense rather than the earnest-play-and-silk-scarves one. Culture collections are a little-celebrated but essential part of modern research. To study a disease scientists need reliable samples. These are the places—the libraries of maladies—that provide them.

Britain has four national culture collections (one each for bacteria, viruses, fungi and cell lines) as well as smaller independent ones. Whatever their specialism, all do more or less the same thing: they store the cultures that matter, and have done so for a long time. This makes them, says Mr Baker, “like a microbiological ice core…[of] infectious diseases”.

Britain has one of the deepest and most august bacterial ice cores in the world. Britain’s national bank of bacteria, the National Collection of Type Cultures (nctc), was founded in 1920, though its oldest sample—it inherited some from other collections—is a vintage 1885 E. coli. Among its celebrity strains is a dose of Haemophilus influenzae believed to have come from Alexander Fleming’s own nose. (That one, acknowledges Sarah Alexander, the head of all four collections and curator of this one, has “sentimental” value.)

The bacterial collection is kept, in part, behind razor wire in Colindale, a suburb of North London. Its prices might be openly available; its samples are not. To order them requires passing several layers of security—more for the nastier ones, which demand licences, training and security checks. The store room itself is bright, cool, clinical and filled with the sort of filing cabinets to be found in any office.

Until you open them. Inside are rows and rows of small, numbered glass ampoules filled with powder. In one is nctc 10418, better known as E. coli. In another is nctc 14208, which causes “super gonorrhoea”. nctc 13142, a pale yellowish powder, is antibiotic-resistant mrsa. Round the corner, behind more layers of security, are nctc 10340 (which causes anthrax), nctc 13912 (tb) and nctc 12945 (cholera). This is where catastrophe is catalogued.

The collection also enables diseases to be deciphered and their history to be written. Over the past few years researchers at the Wellcome Trust Sanger Institute in Cambridge have taken 3,000 samples from here and sequenced their dna. To take a century-old strain and to read its stream of as, cs, ts and gs, says Professor Nicholas Thomson, who leads the research, is like opening “a whole history book”. Bacteria have been sequenced before—but not at this scale or to this depth in time.

History and genomics can feel like an odd combination. Conventional historians tend to pay little attention to maladies. Apart from the occasional Pepys or Procopius, most prefer grander topics for their pens than an outbreak of buboes or a troublesome bout of diarrhoea. And the science of genomics is the sort of whizzy speciality that seems designed for the present and future tenses, for the diseases that threaten today and the cures that might be discovered tomorrow.

This attitude, says Mr Thomson, is wholly mistaken. History is crucial to understanding disease. Unlike the holdings of conventional libraries, the genetic texts of bacteria are constantly evolving. Culture collections offer texts that are frozen in time. These are not first editions but they are certainly earlier editions. Sequence them and researchers can therefore see how this change in the script led to that disease suddenly spreading or becoming more virulent. Such collections are, says Mr Thomson, “now more relevant than they’ve ever been”.

To understand how important such research can be, it helps to visit another, private collection of samples—this one held in Surrey by an organisation called cabi. Behind a locked door sit some 28,000 fungi, many of them in glass jars. Like the dreams in the bfg’s cave, each fungus behaves differently inside its container. Some are formless blobs, others like snowflakes, others still like little puffs of smoke. In one jar a fungus has formed a sinister dark blob; this is imi 173135, better known as Dutch elm disease. In another a fungus has turned into a pale, flesh-coloured splodge: that one is imi 181530, potato blight.

Such libraries matter because they contain death, but also because they contain possibility. In any one of them might lie “genes or isolates that you’d suddenly recognise to be really important”, says Mr Thomson. Science and serendipity dance together—and the collection in Surrey offers perhaps the best example in the world.

Inside one of its rooms stands a tall, grey safe. Inside the safe is a large green box, and inside that is another, little larger than a matchbox. In old-fashioned cursive writing its label tells you that this is sample “imi 24317”. Open it and you see a small, underwhelming smear of brown, as if gravy had been spread on a glass slide. This is Fleming’s other, and better-known, bequest to the world—Penicillium notatum. ■

This article appeared in the Britain section of the print edition under the headline "Cultural history"

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