Scientists decode how methane-eating bacteria create 'green' fuel

Scientists have identified an enzyme that helps some bacteria remove methane from the environment and convert it into a usable fuel — paving the way for a creating a novel, sustainable source of energy.

Known for their ability to methanotrophic bacteria have long fascinated researchers. A team from the Northwestern University in the US found that the enzyme responsible for the methane-methanol conversion catalyses this reaction at a site that contains just one copper ion. The finding could lead to newly designed, human-made catalysts that can convert methane — a highly potent greenhouse gas — to readily usable methanol with the same effortless mechanism.

“The identity and structure of the metal ions responsible for catalysis have remained elusive for decades,” said Amy C Rosenzweig, from Northwestern University. “Our study provides a major leap forward in understanding how bacteria methane-to-methanol conversion,” Rosenzweig said in a statement. “By identifying the type of copper center involved, we have laid the foundation for determining how nature carries out one of its most challenging reactions,” said Brian M Hoffman, from Northwestern.

The study, published in the journal Science, showed that by oxidising methane and converting it to methanol, methanotrophic bacteria (or “methanotrophs”) can pack a one-two punch. Not only are they removing a harmful greenhouse gas from the environment, they are also generating a readily usable, sustainable fuel for automobiles, electricity and more. Current industrial processes to catalyse a methane-to-methanol reaction require tremendous pressure and extreme temperatures, reaching higher than 1,300 degrees Celsius.

Methanotrophs, however, perform the reaction at room temperature and “for free.” “While copper sites are known to catalyse methane-to-methanol conversion in human-made materials, methane-to-methanol catalysis at a monocopper site under ambient conditions is unprecedented,” said Matthew O Ross, a graduate student at Northwestern. “If we can develop a complete understanding of how they perform this conversion at such mild conditions, we can optimise our own catalysts,” said Ross.