New scientific research has a pair of energy companies betting that the future of the U.S. natural gas industry lies in persuading microorganisms to treat old coal deposits like all-you-can eat buffets.

Coal, researchers have found, is full of microbes that consume the fossil fuel and break it down into methane gas. Two companies want to take advantage of this naturally occurring phenomenon on a large scale to create vast amounts of natural gas in energy-rich places like Wyoming.

"Once you figure out the recipe that feeds the bugs and gets them reactivated, it's pretty simple," said Bob Cavnar, chief executive of Luca Technologies.

Luca and Ciris Energy have begun experimenting with using this type of microbe-friendly formula in gas wells drilled into coal deposits years ago. The companies have been spiking the wells with substances including calcium, magnesium, phosphate and glycerol, which encourage the micro-organisms to reproduce, feed and release the coveted methane gas.

The hope is to get old and nearly tapped-out coal-bed methane wells to double or perhaps triple gas production.

The process works on a smaller scale, said Michael Urynowicz, a researcher at the University of Wyoming who has studied using microbes to turn coal into methane.

"The question is, at the field scale, how economically viable it will be?" he said.

Some worry it will contaminate the groundwater that supplies more than 6,000 area homes. What Luca calls "nutrients," Jill Morrison of the Powder River Basin Resource Council calls "chemicals."

"They make it sound like it's yogurt and granola or something. It's not," Morrison said. "I'm not saying that maybe this technology doesn't have some promise at some point. But I don't think we're there, and we don't know enough about it."

The experiment comes in the midst of a natural gas boom that has seen companies in several states just begin to tap vast gas deposits only now being recognized for their enormous potential.

To many, those reserves look all the more attractive while the Japanese nuclear crisis raises worries about nuclear energy and the Gulf oil spill casts doubt on tapping the nation's best remaining oil deposits.

But drilling for gas can require multimillion-dollar investments to bore thousands of feet into the ground. Such wells produce a lot of gas quickly, Cavnar said, but production falls off before long, requiring companies to drill more and more sites to remain profitable.

If successful, the microbe technology could help prolong the future of Wyoming's gas industry, which supports tens of thousands of jobs and provided $1.1 billion in tax revenue to the state in 2009.

Luca officials cast aside environmental concerns, saying its process for tapping into natural gas is more eco-friendly and efficient than drilling because the wells, roads and pipelines already are in place. Acquiring methane from existing coal beds requires very little new infrastructure, Luca says, and puts to use byproduct groundwater by pumping the water back down into the coal-bed methane wells.

About 30,000 coal-bed methane wells have been drilled in the Powder River Basin in northeastern Wyoming over the past 15 years. About half are nearly or completely tapped out. "We think the source here is huge for us to be able to go in and reactivate those wells and start producing gas again," Cavnar said.

Thousands of different microbes _ no one knows exactly how many species are down there _ live in the thick coal seams several hundred feet beneath the rolling prairie in northeast Wyoming.

Luca has been doing DNA research to identify the fewer than 100 species which play different roles in breaking down the complex organic molecules in coal into a single simple molecule, said Roland DeBruyn, the company's vice president of engineering.

"The microbes, they're really working in communities," DeBruyn said. "They're kind of taking different pieces of the chain apart. And in the end, you're left with the smallest pieces of the chain, which is basically methane."

The other company looking to tap into the new source of energy, Ciris Energy, got a $4.8 million matching state grant in 2009 to build an above-ground pilot facility that would employ microbes to turn coal into methane.

Wyoming has a substantial interest in such investments: About 40 percent of the U.S. coal supply comes from Wyoming, providing more than $2 billion in economic benefit to the state each year. Amid concern about climate change, the federal government estimates 15 percent of total U.S. carbon dioxide emissions come from burning Powder River Basin coal. Burning methane, however, yields half as much carbon dioxide as burning coal.

The Ciris Energy plant remains on the drawing board. Meanwhile, the company is waiting for state regulators to finish writing rules for methane farming before experimenting with any more gas wells.

"It would be small-scale to start. Sixteen wells to 64 wells, something in that range," said Robert Downey, president and founder of Ciris Energy.

Already the company's environmental record is less than spotless. Wyoming regulators recently fined Ciris Energy more than $26,000 after a whistleblower reported that Ciris put chemicals in the ground without a state permit; Downey said another company with an interest in the wells was supposed to get the permit.

For their part, Luca officials compare the approach to taking vitamins.

"If you take one a day, then that's good," said Roland DeBruyn, Luca's vice president of engineering. "If you eat the whole bottle, you might have a serious health problem because that's just too much."