Darwin's Dust discloses microbial hitchhikers
(January 18th 2008) Lying on racks in the cellars of natural history museums, many treasures await rediscovery. One of them - hermetically sealed old dust - has recently been dusted off. Karin Hollricher
In 1851, Christian Gottfried Ehrenberg wrote about his dust collection: "Probably, even in 100 years' time, research will find interest in this carefully collected (dust) material, be it for meteorology or for the study of organic life within." Ehrenberg was one of the the 19th century's most innovative natural scientists, founder of the fields of micropaleaontology and microbiology (he gave the name to bacteria').
And he was right. Researchers from Germany and Switzerland are now able to revive and identify bacteria and fungi from dust samples collected between 1812 and 1838 by Charles Darwin and other contemporaries, since stored in Ehrenberg's collection (currently housed in the Museum of Natural History in Berlin).
The scientists opened a few vessels from this irreplacable collection. Their motivation is that new technologies, like genotyping, now enable identification of microbes, even from very small samples.
And the dust does indeed accomodate life. They could repick and identify 17 spore-forming bacterial species and two slow-growing fungal species (
Environ. Microbiol. 2007, 9, pp. 2911-2922). Geochemical analysis revealed that this historic dust, collected over the Atlantic Ocean and Barbados, did in fact originate from the Sahara, not the Carribean. Nowadays, we know that storms can blow large quantities of dust long distances from the Sahara across the Atlantic. These results support the so-far unproven theory that sand can effectively transport viable microorganisms on intercontinental scales.
© Photography:
SAMUM - SAHARAN MINERAL DUST EXPERIMENT
