By Sid Perkins
Geologists are studying bacteria nowadays. It’s not that the rock hounds have gone soft. Instead, they’ve found that geological processes once attributed solely to simple inorganic chemistry have microbial fingerprints all over them. In rocky venues ranging from abandoned mines in California to water wells in Bangladesh to hydrothermal vents on the seafloor, bacteria are at work. If the microbes aren’t driving the underlying chemical reactions in those places, they’re at least taking advantage of the energy that’s being released by these reactions.
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Researchers are finding that bacteria living on the seafloor may be key players in the chemical reactions that slowly transform the rocks there, and in the process, help balance ocean chemistry. Others are discovering that microbes can create tiny mineral particles by extracting exceedingly small concentrations of dissolved metals from the fluids that course through soils and sediments. In at least one instance, bacteria probably created a significant deposit of high-value mineral ore (see “Microbial Machinations,” below).