Tiny builders with huge appetite

Researchers: Bacteria can eat holes in the rock

Some large cave systems could be caused by sulphur bacteria. The American scientists have discovered in the investigation of a cave in the U.S. state of Wyoming. The bacteria produce a waste product of their metabolism, sulphuric acid, capable of converting the limestone into gypsum. Since gypsum is water soluble, it will over time of water leached from the rock, so that cavities form. About the study of geologists to Annette Summers Engel from the University of Texas at Austin reported the online service provided by the journal Nature.

So far, scientists had assumed that the sulphuric acid without the aid of bacteria arises: If hydrogen sulphide, which causes many natural sources of the characteristic odor of rotten eggs rises to the surface, it can react with oxygen in the air, forming sulphuric acid. The acid in turn reacts with the calcium carbonate (lime) in the rock and converts it into calcium sulphate (gypsum) in order. The calcium sulphate is dissolved in the groundwater and form small cavities, which are getting bigger over time.

Annette Summers Engel and her colleagues presented their study at the Lower Cane Cave in Wyoming, however, that there is a lot of hydrogen sulphide released to little to explain the formation of the large cavity. Instead, the researchers found white spots on the floor of the cave, which consisted of bacteria. These bacteria use hydrogen sulphide as the other organisms, carbohydrates, in order to gain energy. This produces sulphuric acid as a waste product that has created over time, the big cave.

Since the cave studied by geologists with some 10,000 years ago is not particularly old, the researchers suspect that the bacteria can eat even more time with much larger holes and even entire cave systems in the rock.