Did Bacteria Fuel World's Worst Extinction? Nickel-eating
bacteria may have worsened the mass die-off some 250 million
years ago, scientists suggest. (Shown here, International Space
Station astronaut Ron Garan captures one of the 16 sunrises they
see each day, on Aug. 27, 2011.) SAN FRANCISCO — Nickel-eating
bacteria may have worsened the world's worst mass die-off by
producing huge amounts of methane, a new study suggests. The
study is the latest attempt to explain how most of the world's
ocean species died off in just a few hundred thousand years at
the end of the Permian era, about 250 million years ago. The
researchers presented their findings Tuesday (Dec. 4) here at
the annual meeting of the American Geophysical Union. The study
proposes that a series of steps caused the mass extinction, but
that bacteria played a key role. First, massive volcanic
activity in Siberia released nickel into the atmosphere, which
somehow reached the ocean. As a result, populations of ocean-
dwelling bacteria that use nickel