Gene sequencing advance bolsters biofuels potential

A collaborative research project between the U.S. Forest Service Forest Products Laboratory (FPL) and the Department of Energy Joint Genome Institute has advanced the quest for efficient conversion of plant biomass to fuels and chemicals.

“We have sequenced and assembled the complete genome of Pichia stipitis, a native xylose-fermenting yeast,” says Thomas Jeffries, research microbiologist at FPL and a professor of bacteriology at the University of Wisconsin–Madison. The results of this research project will be published in the scientific journal Nature Biotechnology in April, and the report is currently available online.

The sequencing of P. stipitis marks an important step toward the efficient production of biofuels because the yeast can efficiently ferment xylose, a main component of plant lignocellulose. Xylose fermentation is vital to economically converting plant biomass to fuels and chemicals such as ethanol.

“A better understanding of the genetic structure of this yeast allows us to determine how specific genes are used in fermentation and then reengineer them to perform other desired functions,” says Jeffries.

For example, Jeffries explains that the fermentation of both glucose and xylose is critical to efficient bioconversion because xylose is so abundant in hardwoods and agricultural residues. However, when glucose is present, the fermentation of xylose by P. stipitis is repressed. Using their knowledge of the genetic makeup of the yeast, researchers will be able to alter the expression of the genes so that both glucose and xylose are fermented simultaneously. This will increase the efficiency, and improve the economic viability, of the process.

The U.S. Forest Service Forest Products Laboratory, with its mission to conserve and extend the country’s wood resources, is a partner in the Wisconsin Bioenergy Initiative, an effort launched by the UW–Madison College of Agricultural and Life Sciences to accelerate the development of bioenergy resources. FPL scientists have been studying P. stipitis for 20 years and in that time have isolated and characterized several genes, developed improved strains, and recently licensed technology to a biotech firm for commercial development.

“We are very proud of Tom’s research and the breakthroughs he and his colleagues continue to make,” says FPL Directory Chris Risbrudt. “Publication in a journal of such importance to the scientific community demonstrates the capability of FPL’s researchers and our status as a world-class facility.”

“The genetic blueprint reported in this paper will be at the foundation of new biofuels technology that will be developed under the auspices of the Wisconsin Bioenergy Initiative,” reports Tim Donohue, professor of bacteriology. “It will have benefits in making ethanol production from plant sugars more efficient in the short term and it is likely to help develop long-term bioenergy solutions that help Wisconsin assume a position of leadership in the rapidly growing biofuels economy.”