Bacteria made quick work of the tons of methane that billowed into the Gulf of Mexico along with oil from the Deepwater Horizon blowout, clearing the natural gas from the waterway within months of its release, researchers reported Friday.

The federally funded field study, published online in the journal Science, offers peer-reviewed evidence that naturally occurring microbes in the Gulf devoured significant amounts of toxic chemicals in natural gas and oil spewing from the seafloor, which researchers had thought would persist...