Bacteria reveal long-held secret

by Lynne Kozarek

Buried in the sunless muck beneath the oceans, tiny bacteria concealed the secret to converting a harmful pollutant into a useful product. Two University researchers collaborated to unlock the secret, hidden for ages in the murky deep.
Professors John Lipscomb and Larry Que began studying the bacterium Methlosinus trichosporum in 1985, eventually discovering that the microbe contains an enzyme that does what scientists have failed for decades to achieve — convert methane into methyl alcohol.
Lipscomb, a professor of biochemistry, said that the conversion of methane to methyl alcohol, or methanol, has benefits for both industry and the environment.
“People in industry are interested in a way to convert natural resources into what we now get from crude oil,” said Que, a professor of chemistry at the University. “Methane will outlast supplies of crude oil.”
But the breakthrough will allow more than just the replacement of petroleum resources. By breaking down methane, it might become easier to transport and store natural gas.
“It is very difficult to transport natural gas as a gas,” Lipscomb said. “This will help us transfer it into methyl alcohol (a liquid) and make it easier to transport.”
The conversion of methane to methanol is also environmentally sound because it can reduce the amount of harmful methane gas in the air.
Methane traps heat in the Earth’s atmosphere; scientists believe the gas contributes to the greenhouse effect, which environmental scientists blame for climatic changes.
The bacteria contain an enzyme that breaks down methane. Lipscomb and Que’s breakthrough was discovering how.
Methane, the main component in natural gas, consists of molecules that are not easily converted into a different substance.
“No one has been able to break the (methane) molecule to make methanol,” Lipscomb said, “but bacteria (break down the molecule) with 100 percent efficiency.”
Lipscomb and Que found that the enzyme contained two iron atoms that react with oxygen atoms to form a diamond shape.
“Now that we know what it is,” Que said, “we have to understand why nature chose this.”
Que said that the knowledge of the diamond shape in the enzyme shows scientists how it works, which is important for using the enzyme’s ability to convert methane to methanol.
Both researchers believe the discovery of the diamond-shaped core in the enzyme will have an impact that will reach far into the future; their work, at least, will have to continue for some time before the enzyme is fully understood.
“We’re about halfway through the problem,” Lipscomb said. “We are working to understand the enzyme mechanism and how the interactions occur.”
Before federal funding was provided, the project was funded by money from the University’s Graduate School and the Minnesota Medical Foundation.
Federal funding for the research began nine years ago and is provided by grants totaling $500,000 per year from the National Institutes of Health and the National Science Foundation.