Three continents. Nine countries. Cemeteries from Antwerp to Barcelona to Hellerup. Thought cemeteries were only for the dead? Not so, say National Science Foundation-funded scientists. The researchers found that graveyards are in fact places of the undead -- in the form of microbes on tombstones. The researchers, who took samples from the surfaces of 149 gravestones in the Cementerio de Montjuic in Barcelona, Spain; El Queremal Cementario in Valle de Cauca Province, Colombia; Dory Hill Cemetery in Black Hawk, Colorado; and other graveyards, recently published their results. To find out which microbes grow on rock surfaces and how they do so, the researchers used toothbrushes to collect samples from tombstones. Several characteristics of each tombstone were recorded, including rock type, length of tombstone exposure (based on date of death), direction of the sampled face (cardinal direction) and surface texture (polished or unpolished). The researchers found that rock type is a good predictor of which microbe species grow on tombstones. For example, microbes that flourish on granite gravestones in Maine are more like those growing on granite gravestones in Belgium than they are to those on limestone tombstones just feet away. The results show that gravestones are great places for understanding microbes' survival on rock surfaces and their contributions to rock weathering.
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