Fungi the key to efficient biomass breakdown and cheap biofuels?

Bioenergy researchers are looking for ways to increase the efficiency of biofuel production in an unusual place – fungi.

Finding a cost-effective way to breakdown bioenergy crops is one of the biggest obstacles to sustainable biofuels production. A team from the University of California, Santa Barbara are focusing their research on the estimated 1.5 million species of fungi on earth which can collectively break down almost any substance.

In an article published in Nature Microbiology, the team announce they have found that early lineages of fungi can form complexes of enzymes capable of degrading plant biomass. By consolidating these enzymes, in effect into protein assembly lines, they can team up to work more efficiently than they would individually.

"There are protein complexes in bacteria called cellulosomes that pack together the enzymes to break down plant biomass," said study senior author Michelle O'Malley of UC Santa Barbara. "The idea is that these clusters are better at attacking biomass because they are keeping the different enzymes in place with plugs called dockerins so they work more efficiently. This has been detailed in bacteria for more than 20 years, but now seen for the first time in fungi."

The team of scientists took advantage of two US Department of Energy (DOE) Office of Science User Facilities, the DOE Joint Genome Institute (JGI) at Lawrence Berkeley National Laboratory (Berkeley Lab) and the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL) to gather cutting edge insights into the genomes of five different species of fungi, in turn learning how the complexes of enzymes responsible for degrading plant biomass are formed.

"Proteomics data and genomics data enabled us to figure out what these complexes are and go hunting for them in other genomes," O'Malley said. "The three genomes are really well resolved to the point where you can start looking at what's there, what's regulating enzyme production, and how enzymes have evolved."

Learning more about the protein mechanisms of biomass degradation is a crucial part of the DOE’s plans to develop sustainable biofuels from plant feedstocks. Greater knowledge presents the opportunity to exploit the fungi’s capacities with synthetic biology or metabolic engineering approaches.