MADRID, Spain -- Scientists studying a speck of pigment from a 16,000-year-old cave painting have found mysterious bacteria they suspect may be nibbling on the Sistine Chapel of Paleolithic art.
The main chamber of the Caves of Altamira in the northern Cantabria region is dominated by 21 splendid bison painted in red and black, seeming to charge across a low, limestone ceiling.
Discovered in 1868, the cave complex became a tourist magnet and by the 1970s received 3,000 visitors a day -- plus their body heat and moisture from their breath. Both are traditionally blamed for deterioration of the images. Now, only 10 people a day are allowed in.
But microbiologists with Spain's top scientific research body and colleagues from the University of Vienna now want to determine if bacteria also play a role in the fading of the artwork.
A team headed by Cesareo Saiz-Jimenez of the Scientific Research Council removed a tiny sample of reddish pigment from a bison and found it contained a wealth of bacteria.
Just over half were garden-variety, but there were also two surprises.
First, about a quarter of the bacteria were Acidobacterium, which scientists know little about because only a few species can be cultivated in laboratories and thus studied. Their metabolism and function in nature are enigmas.
Of the ones taken from the bison, Saiz-Jimenez said Friday: "We don't know what they are doing there." But scientists suspect they may reduce iron. When pigment loses iron, it also loses color.
The team has asked Altamira's administrators for permission to go back in to do more tests.
If it turns out the bacteria are eroding the paintings, one way to counter them is to dim the lights, Saiz-Jimenez said. Light stimulates growth of airborne algae which are a source of food for bacteria.