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Images: Microbes That 'Eat' Natural Gas

A German-American team of scientists has identified previously unknown bacteria that can break down hydrocarbons in natural gas via a previously unknown biochemical process?without oxygen. (Katrin Knittel and Florin Musat, Max Planck Institute)

The newly identified bacteria use sulfate instead of oxygen to respire. In the process, they convert sulfate (SO4) into hydrogen sulfide (H2S), and oxidize the short-chain hydrocarbons (ethane, propoane, and butane) into carbon dioxide (CO2). (Illustration by Friedrich Widdel, Max Planck Institute)

Stefan Sievert, a microbiologist from Woods Hole Oceanographic Institution, use molecular methods?gene cloning, sequencing, and then phylogenetic analyses?to identify the unknown microbes by their DNA and determine where they lie on the tree of life.

The new-found bacteria were isolated from seafloor sediments that were anoxic (devoid of oxygen) from the Guaymas Basin in the Pacific Ocean and from the Gulf of Mexico. In these places, heat and pressure have squashed and cooked the tiny remains of plants and animals into different-sized chains of carbon and hydrogen atoms called hydrocarbons. These hydrocarbons comprise natural gases, which build up deep in the seafloor (or under the crust in certain terrestrial environments) and occasionally ?seep? through the sediments, sometimes to the surface. (Map by Jack Cook, Woods Hole Oceanographic Institution)

Yellow mats of bacteria form atop seafloor sediments in the Guaymas Basin, where the new natural-gas-'eating' bacteria were found. (Woods Hole Oceanographic Institution)