Super-fermenting fungus genome sequenced

On the road to making biofuels more economically competitive with fossil fuels, there are significant potholes to negotiate. For cellulosic ethanol production, one major detour has being addressed with the characterization of the genetic blueprint of the fungus Pichia stipitis, by the U.S. Department of Energy Joint Genome Institute and collaborators at the U.S. Forest Service, Forest Products Laboratory.

The research, entailing the identification of numerous genes in P. stipitis responsible for its fermenting and cellulose-bioconverting prowess, and an analysis of these metabolic pathways, is featured in the March 4 advanced online publication of Nature Biotechnology.

P. stipitis is the most proficient microbial fermenter in nature of the five-carbon “wood sugar” xylose—abundant in hardwoods and agricultural leftovers, which represent a motherlode of bioenergy fodder.

“Increasing the capacity of P. stipitis to ferment xylose and using this knowledge for improving xylose metabolism in other microbes, such as Saccharomyces cerevisiae, brewer’s yeast, offers a strategy for improved production of cellulosic ethanol,” said Eddy Rubin, DOE JGI Director. “In addition, this strategy could enhance the productivity and sustainability of agriculture and forestry by providing new outlets for agricultural and wood harvest residues.”

Ligonocellulosic biomass, a complex of cellulose, hemicellulose, and lignin, is derived from such plant-based “feedstocks” as agricultural waste, paper and pulp, wood chips, grasses, or trees such as poplar, recently sequenced by DOE JGI. Under current strategies for generating lignocellulosic ethanol, these forms of biomass require expensive and energy-intensive pretreatment with chemicals and/or heat to loosen up this complex. Enzymes are then employed to break down complex carbohydrate into sugars, such as glucose and xylose, which can then be fermented to produce ethanol. Additional energy is required for the distillation process to achieve a fuel-grade product. Now, the power of genomics is being directed to optimize this age-old process.

“The information embedded in the genome sequence of Pichia has helped us identify several gene targets to improve xylose metabolism,” said Pichia paper lead author Thomas W. Jeffries of the Forest Products Laboratory in Madison, Wisconsin. “We are now engineering these genes to increase ethanol production.” Jeffries said that yeast strains like Pichia have evolved to cope with the oxygen-limited environment rich in partially digested wood that is encountered in the gut of insects, from where the sequenced strain was originally isolated.

FPL has a Cooperative Research and Development Agreement (CRADA) in place with a New York City-based bioenergy company, Xethanol Corporation, which plans to integrate Dr. Jeffries’ findings into its large-scale biofuels production processes.

Source: DOE/Joint Genome Institute

Related stories:

UCI and CODA Genomics collaborate to re-engineer yeast for biofuel production
Scientists from UC Irvine and CODA Genomics are partnering on new research aimed at turning a common strain of yeast used in the production of beer, wine and bread into an efficient producer of ethanol.
Biotech breakthrough could end biodiesel's glycerin glut
With U.S. biodiesel production at an all-time high and a record number of new biodiesel plants under construction, the industry is facing an impending crisis over waste glycerin, the major byproduct of biodiesel production. New findings from Rice University suggest a possible answer in the form of a bacterium that ferments glycerin and produces ethanol, another popular biofuel.
Producing bio-ethanol from agricultural waste a step closer
Research conducted by Delft University of Technology has brought the efficient production of the environmentally-friendly fuel bio-ethanol a great deal closer to fruition. The work of Delft researcher Marko Kuyper was an important factor in this. His research in recent years has greatly improved the conversion of certain sugars from agricultural waste to ethanol. On Tuesday 6 June, Kuyper received his PhD degree for his research into the subject.
New processing steps promise more economical ethanol production
Why isn't ethanol production growing by leaps and bounds in the face of higher gasoline prices? Ethanol production from cornstarch is a $10 billion dollar business in the United States and 4 billion gallons of ethanol will be produced in 2006. In his 2006 State of the Union address, President Bush called for doubling ethanol production by 2012, and replacing 75 percent of Middle Eastern oil with bioethanol from renewable materials by 2025.
Ethanol byproduct produces green results
Commercial flower and plant growers know all too well that invasive, ubiquitous weeds cause trouble by lowering the value and deterring healthy growth of potted ornamental plants. To control weeds, many commercial nursery owners resort to the expensive practice of paying workers to hand-weed containers. Some growers use herbicides, but efficacy of herbicides is questionable on the wide range of plant species produced in nurseries, and many herbicides are not registered for use in greenhouses.
Shrinking carbon footprints
Would shrinking your carbon footprint, recycling more, and going green be easier if you could monitor your household's environmental impact? That's the question a team of Canadian industry consultants set out to answer. They report their findings in a forthcoming issue of the International Journal of Environmental Technology and Management from Inderscience Publishers.
Research yields pricey chemicals from biodiesel waste
In a move that promises to change the economics of biodiesel refining, chemical engineers at Rice University have unveiled a set of techniques for cleanly converting problematic biofuels waste into chemicals that fetch a profit.
SEX4, starch and phosphorylation
Some of the new molecular mechanisms and regulatory components in starch metabolism have been identified by Dr. Samuel Zeeman and his colleagues. Dr. Zeeman, of the Institute of Plant Sciences, ETH Zurich, in Switzerland, who is the 2007 recipient of the Charles Albert Shull Award, will be presenting this work at the opening Awards Symposium of the annual meeting of the American Society of Plant Biologists in Mérida, Mexico (June 27, 2:30 PM). Mutational and structural analyses by Dr. Zeeman and his colleagues have revealed that starch degradation in Arabidopsis leaves at night differs significantly from the versions traditionally described in textbooks. Specifically, mutations at the Starch Excess 4 (SEX4), Maltose Excess 1 (MEX1) and other loci produce plants unable to metabolize starch to a usable form.

News discussion:

General Science news