MADISON -- A newfound microbe that eats iron and lives in acid-drenched conditions has been identified as a chief suspect in the environmental damage caused by metal ore mining.
Writing in the Friday, March 10, edition of the journal Science, a team of scientists from the University of Wisconsin-Madison report the discovery in an old mine of an archaeon that thrives when metal sulfide ores are exposed to air and water, conditions that mimic hot battery acid. The microbe, the scientists say, is present in such abundance that it is believed to be a key mediator of the process of acid mine drainage, the primary environmental problem associated with the extraction of metal ores from the earth.
The microbe shows an ability to transform the sulfide found in metal ores to sulfuric acid, the chemical pollutant that contaminates mining sites and drains into nearby rivers, streams and groundwater.
"We think this new archaeon might be one of the more important players in catalyzing these reactions," says Katrina J. Edwards, the lead author of the Science article.
Microbial archaea, a branch of life with ancient roots, have different basic characteristics than other microscopic organisms such as bacteria.
Edwards is a geomicrobiologist at the Woods Holes Oceanographic Institute, Woods Hole, Mass. The work, funded largely by the National Science Foundation, was conducted as part of her doctoral thesis at UW-Madison in the lab of Jillian Banfield, a professor of geology and geophysics and a co-author of the study.
The discovery of the new microbe is important because it helps explain how the natural cycle of the conversion of sulfide to sulfuric acid is greatly accelerated around mines. Moreover, the physiological character of the archaeon is of great interest because it has no cell wall, defying the idea that microorganisms tough it out in nasty environments with the help of durable external walls to shield themselves from extreme conditions.