Bugs That Eat Rocks

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These days geologists are studying bacteria as well as rocks.  This is because some bacteria can break down minerals, while others can actually make them.

Some microbes can create tiny mineral particles by extracting small concentrations of dissolved metals from the water that flows through the sediments in which they live.  There is often a dangerous concentration of toxic metals such as iron, zinc, copper and arsenic in the run-off from abandoned mines.  The amounts of these can be increased by the presence of microbes.

Certain acid tolerant micro-organisms speed up the breakdown of the metal-containing minerals on which they feed, causing them to release up to ten times the concentration of metal ions into the water seeping from mines.

In parts of the world where drinking water is obtained from wells, mineral-munching bacteria can pose a serious health risk.  In countries like Bangladesh, where millions of people rely on well water, rocks often contain significant amounts of arsenic, a deadly poison.  Scientists have identified sixteen different microbes that can feed on arsenic containing minerals.  A number of these microbes release arsenic into the well water as they munch on the rocks.

Some scientists suspect that the ocean floor may be nourishing huge quantities of mineral munching microbes.

So next time your cookie is hard to bite, think of the microbes whose food is always rock hard.