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Fungus genes could point to cheap fuel

9th May, 2008

A green fungus might provide a more efficient way to make biofuels such as ethanol.

Researchers at Los Alamos National Laboratory in New Mexico sequenced the complete genome of Trichoderma reesei and found important clues about how it breaks down plant fibres into the simple sugars needed to make plant-based fuel.

The fungus could provide a way to use switchgrass and other nonfood plants to make biofuels. One barrier to using nonfood plants to make biofuels has been the difficulty in converting them into sugar. Food crops such as corn more readily convert.

'Our analysis, coupled with the genome sequence data, provides a road map for constructing enhanced T. reesei strains for industrial applications such as biofuel production,' Diego Martinez of Los Alamos National Laboratory in New Mexico says.

The fungus has already been exploited commercially. 'It has enjoyed a long history of safe use for industrial enzyme production,' Martinez adds.

It uses enzymes it creates to break down plant fibres into the simplest form of sugar, known as a monosaccharide. But it has fewer genes dedicated to the production of cellulose-eating enzymes than other fungi do.

'We were aware of T. reesei's reputation as producer of massive quantities of degrading enzymes. However we were surprised by how few enzyme types it produces, which suggested to us that its protein secretion system is exceptionally efficient,' Martinez says.

T. reesei could be grown on an industrial scale to secrete its fibre-eating enzymes, which in turn could be added to pulped-up plants to produce sugar. The sugar can then be fermented by yeast to produce ethanol.

'Using this information, it may be possible to improve both of these properties, decreasing the cost of converting cellulosic biomass to fuels and chemicals,' Joel Cherry of Demmark-based Novozymes, a biotechnology company that took part in the study, notes.