Passing Milestones
ORNL's BioEnergy Science Center has essentially reached what may be the center's most critical milestone.
ORNL's BioEnergy Science Center opened in 2007. Over the past three years the new program has passed a number of major milestones—many ahead of schedule. Perhaps the center's most critical milestone was the ability to use molecular biology to make plant cell walls easier to break down into their component sugars. While much remains to be done to refine the process, ORNL's Associate Laboratory Director of Biological and Environmental Sciences Martin Keller says the milestone has essentially been reached. He notes that BESC scientists thus far have discovered two exceptional switchgrass lignin genes with the ability to reduce the amount of lignin produced by switchgrass, increase its ethanol production and reduce the amount of enzyme needed to sustain the process. "These new plants are growing in a greenhouse right now and will be planted in field trials next year," Keller adds. Having shown the proofof- concept with these genes, the next challenge is to test additional genes and understand their impacts. More genes targets have been modified, and the testing of the resulting plants has begun. Reaching this milestone demonstrates that the process of producing biofuels from biomass can be made much more efficient and that the cost of conversion can be significantly lowered.
Another of the center's major milestones was proving that consolidated bioprocessing—a one-step process for converting biomass into ethanol—could work. Keller says that Mascoma Corporation, one of BESC's partner organizations, is close to demonstrating that a specially modified strain of yeast can reduce biomass to sugars and ferment the sugars into biofuels in one step. "This is an area in which we have made significant breakthroughs and where we are far ahead of schedule," he says.
Despite the progress, significant challenges remain, such as understanding how various plant cell wall components interact on a chemical level, including how cellulose, hemicellulose and lignin are linked at the molecular level. The challenge has implications for the relative difficulty researchers may encounter in extracting sugar from biomass. Data from recent studies on various molecular interactions have provided hints about which aspects of cell wall structure can be modified to make them easier to break down, allowing sugar to be extracted more efficiently.
Another milestone will be to demonstrate a synergy among the center's advances on a variety of scientific fronts. BESC researchers know, for example, that modifying plant cell walls can boost the efficiency of biofuels production and that consolidated bioprocessing is expected to provide a similar increase in efficiency. Still unknown is whether, if the two techniques are combined, the resulting efficiency increase would be greater than expected.
"We want to know if two plus two can equal five," Keller jokes. Given his insistence that the whole is greater than the sum of its parts, the question remains open.