Cave Paintings Fading From Bacterial Growth

MADRID - Spanish researchers are trying to determine how to deal with an infestation of bacteria that is slowly eating the color out of one of the nation's most prized tourist sites - the Caves of Altamira.

The cave paintings of bison were discovered in 1868 in the northern Cantabria region. The red and black drawings have drawn international visitors into the caves for a peek into prehistoric times. However, with the visitors, numbering 3,000 daily in the 1970s, came body heat, moisture and breath.

Today, only 10 visitors are allowed per day to view the images because scientists fear bacteria brought in by tourists may be responsible for the fading of drawings' color. Samples taken from the images have produced Acidiobacterium - a very rare bacterium that scientists cannot grow successfully in laboratories. Little is know about the organism and researchers cannot determine why they are present within the caves. While they do not understand the Acidiobacterium's metabolism, the team has concluded the organism must thrive on iron, therefore reducing the images' pigment.

The solution is to introduce dim lighting that stimulates airborne algae - a bacterial food source, thereby reducing the amount of iron consumed.

The Spanish government has reportedly built exact replicas of the caves in a museum to further reduce the amount of visitors to the actual site.

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