Yet we know very little about how the complex reaction occurs, limiting our ability to use the double benefit to our advantage.

By studying the enzyme the bacteria use to catalyze the reaction, a team at Northwestern University now has discovered key structures that may drive the process.

Their findings ultimately could lead to the development of human-made biological catalysts that convert methane gas into methanol.

"Methane has a very strong bond, so it's pretty remarkable there's an enzyme that can do this," said Northwestern's Amy Rosenzweig, senior author of the paper. "If we don't understand exactly how the enzyme performs this difficult chemistry, we're not going to be able to engineer and optimize it for biotechnological applications."

The enzyme, called particulate methane monooxygenase (pMMO), is a particularly difficult protein to study because it's embedded in the cell membrane of the bacteria.