ASPEN, Colorado - The bacteria behind food poisoning worldwide, the mighty E.coli, could be turned into a commercially available biofuel in five years, a US scientist told technology industry and government leaders on Tuesday.

Several companies are working on the technology, which has been proven in laboratories but is not yet yielding enough fuel to be commercially viable, scientist Jay Keasling told the Aspen Ideas Festival on Tuesday.

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Keasling, chief executive officer of the US Department of Energy's Joint BioEnergy Institute, has pioneered research in biofuels based on substances ranging from yeast to E.coli and expects E.coli fuel production to improve.

Already, a similar technology is using E.coli bacteria to make plastics that are finding their way to stores in products including carpets. Although there is nothing dangerous in E.coli plastic, companies usually don't mention the unusual origins to consumers, he said.

When ingested by humans, E.coli can be dangerous, even fatal. Earlier this year, an outbreak in Germany caused widespread illness and panic, and led to more than 30 deaths.

While biofuels eventually have enormous potential for reducing fossil-fuel consumption, "it's going to be a long time before biofuels are a serious challenge to petroleum," he said.

Reaching critical mass was likely to take at least two decades, he said.