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Researchers have long been fascinated with methanotrophic bacteria, i.e., bacteria capable of turning the potent greenhouse gas methane into usable fuel, yet the exact mechanism of how that happens remained obscure, primarily due to contradictory results obtained using biochemical, spectroscopic and crystallographic techniques.
Luckily, the mystery has finally been solved – an interdisciplinary team of researchers at Northwestern University took a closer look at the enzyme responsible for the methane-methanol conversion (called the particulate methane monooxygenase, or pMMO) and found that it does its magic at a site which contains only one copper ion.
“The identity and structure of the metal ions responsible for catalysis have remained elusive for decades,” said co-senior author on the study Amy C. Rosenzweig. “Our study provides a major leap forward in understanding how bacteria perform methane-to-methanol conversion.”
Discovery of the mechanism whereby methanotrophic bacteria turn free methane into methanol could pave the way for devising man-made catalysts to produce relatively clean fuel and thereby bolstering our efforts at fighting climate change. Image: NIAID via flickr.com, CC BY 2.0
The oxidation and subsequent conversion of methane into methanol could be doubly good for the environment, as the process not only removes the potent gas from the atmosphere, but also produces sustainable fuel for vehicles, the generation of electricity, and much more.
Whereas the currently available industrial process for catalysing a methane-to-methanol reaction necessitates tremendous pressure and temperatures exceeding 1,300 degrees Celsius, methanotrophs are capable of achieving the same at room temperature and without any great expense.
“While copper sites are known to catalyze methane-to-methanol conversion in human-made materials, methane-to-methanol catalysis at a monocopper site under ambient conditions is unprecedented,” said first author on the paper graduate student Matthew O. Ross. “If we can develop a complete understanding of how they perform this conversion at such mild conditions, we can optimize our own catalysts.”
The study was published on 10 May in the leading academic journal Science.
Sources: study abstract, news.northwestern.edu