How long can organisms survive in a state of cryptobiosis? For nematodes, the record is 39 years. Rotifers (another group of microscopic invertebrate animals) have been revived from dried herbarium specimens that were 120 years old. Plant seeds can lie dormant for many years. The ancient English herbs weld and mullein grew from soil from a Carthusian priory that was closed during the dissolution of the monasteries by Henry VIII between 1536 and 1540. These 400-year-old seeds, the plants of which had not been seen in England since medieval times, grew after the soil containing them was brought to the surface after an archaeological dig. The oldest seed ever germinated is a 1300-year-old lotus seed from China.
Microorganisms hold the most remarkable records for longevity. Bacteria have grown from spores from a 118-year-old can of meat (canned veal taken on Parry's Arctic expedition, 1820-1830). Beer has been brewed from yeast isolated from a bottle of porter ale which was taken from the wreck of a sailing barge that lay off the coast of the English port of Littlehampton for 166 years. Somewhat more controversial are reports of bacteria that may be millions of years old. Bacteria have been isolated from rocks, salt deposits and permafrost (permanently frozen soil). Many have doubted these reports since it is difficult to prove that samples have not been contaminated with bacteria of more recent origin. The most convincing claims concern those from specimens that are naturally protected against contamination. Bacterial spores (from the genus Bacillus) were isolated from a bee preserved in amber estimated to be 20-40 million years old. The material was protected against contamination by the amber, the surface of which was carefully sterilised before the sample was taken. Bacteria (also a Bacillus) have been isolated from liquid inclusions enclosed within salt crystals and estimated to be 250 million years old. Like those isolated from amber, the material was protected from contamination by the salt crystal and extreme care was taken to prevent contamination during sampling. If the evidence for these sorts of claims holds up, there is no reason not to believe that bacterial spores can be immortal.
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