A quicker and less energy intensive method of breaking down lignocellulose by using brown-rot fungus has been developed by a team of researchers operating as part of the EU Biorenew ('White Biotechnology for added value products from renewable plant polymers: Design of tailor-made biocatalysts and new industrial bioprocesses') project. Funded with EUR 9.5 million under the EU's Sixth Framework Programme (FP6) the current study, involving more than 50 researchers from several countries, including Austria, the Czech Republic, Germany, France and Spain, combined their efforts to systematically examine the genome and biochemistry of the P. placenta fungus.

Extensive investigations revealed that the fungus completely lacked genes to produce cellulase (an enzyme that breaks down cellulose), but had a unique series of enzyme systems that acted together to degrade cellulose.

"The microbial world represents a little explored yet bountiful resource for enzymes that can play a central role in the deconstruction of plant biomass-an early step in biofuel production," said Dr Eddy Rubin, Director of the US Department of Energy's Joint Genome Institute. "The brown-rot P. placenta's genome offers us a detailed inventory of the biomass-degrading enzymes that this and other fungi possess."

Current research efforts focus on extracting sugars from perennial grasses and fast-growing trees such as poplar that are bred specifically as biomass for biofuels. Finding an appropriate mix of enzymes to speed up this process will be invaluable for getting the most out of the biomass while using the least energy.

"Nature offers some guidance here," explains Dr Dan Cullen of Forest Products Laboratory in the US. "Postia has, over its evolution, shed the conventional enzymatic machinery for attacking plant material. Instead, the evidence suggests that it utilises an arsenal of small oxidizing agents that blast through plant cell walls to depolymerise the cellulose. This biological process opens a door to more effective, less energy-intensive and more environmentally sound strategies for more lignocellulose deconstruction."

The genetic information gleaned by the scientists goes a long way to explain the complex biochemical machinery that lets brown-rot fungi destroy wood so easily. This new knowledge is expected to open the door for major innovations in the biofuels industry.

"For the first time we have been able to compare the genetic blueprints of brown-rot, white-rot and soft-rot fungi which play a major role in the carbon cycle of our planet," said Dr Randy Berka of Novozymes, Inc. in the US. "Such comparisons will increase our understanding of the diverse mechanisms and chemistries involved in lignocellulose degradation. This type of information may empower industrial biotechnologists to devise new strategies to enhance efficiencies and reduce costs associated with biomass conversion for renewable fuels and chemical intermediates."