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Biofuels II: Basic Plant Science Meets a New Challenge

Posted Oct. 2, 2006

In the September issue of Ag News and Views, Dr. Joe Bouton described several of the Foundation's ongoing programs on biofuel feedstocks, or plant materials used in producing biofuel, particularly the efforts to breed improved switchgrass varieties. The Noble Research Institute is placed to become a national leader in the development of novel feedstocks, particularly for bioethanol production. In this article, I briefly explain how activities in Noble's Plant Biology Division will contribute to these efforts.

The U.S. Department of Energy recently committed significant competitive grant funding for basic science to underpin a new bioenergy industry. In August, the Plant Biology Division was awarded $700,000 from DOE in support of a project aimed at determining the impacts of lignin, an insoluble polymer found in plant cell walls, on the bioethanol processing efficiency of alfalfa and wheat. The work on wheat is in collaboration with scientists from Kansas State University.

There are two stages involved in bioethanol production from lignocellulosic biomass (plant material from which the ultimate source of ethanol is the sugars in the plant cell walls, in contrast to corn seed, where starch is the origin of the ethanol): breakdown of cell wall polysaccharides (cellulose and hemicellulose) to their component sugars and subsequent fermentation of the sugars to ethanol. The presence of lignin reduces access of enzymes and chemicals to hemicellulose and cellulose, thus reducing the efficiency of hydrolysis.

Surprisingly few studies have experimentally addressed the impacts of altering the properties of lignocellulose on biofuel saccharification (sugar release from cell walls) and subsequent fermentation. The purpose of the DOE-funded project is to determine the effects of genetically modifying lignin composition and content on biofuel processing efficiency. Many of the genetically modified plants already have been generated as part of a project studying impacts of lignification on forage digestibility.

For bioethanol to become an economic proposition, increases in efficiency are required at every stage of the process, from biomass yield through fermentation. Plant Biology Division researchers are beginning to tackle several of these issues. A new program has been initiated to study the effects of fungal endophytes (fungi which live within plant tissues, but which benefit rather than reduce plant performance) on the fitness and yield of switchgrass and other biofuel crops. Members of our plant virology group have been developing viruses that preferentially infect grasses as "vectors" for introduction of plant genes into target species such as switchgrass. This will provide rapid screens for determining which genes are best able to modify cell wall properties to benefit biofuel processing. Our programs in plant metabolomics (high-throughput analytical chemistry) will be crucial for determining which chemicals from the (modified) plant are potentially inhibitory to the microorganisms used for the final sugar fermentation stages.

Finally, the Plant Biology Division has strong programs in structural biology and cellular imaging, technologies important for the design of better enzymes for degrading plant cell walls and for understanding the impacts of cell wall modification on cell structure and function, respectively.

It is interesting to reflect on how the Noble Research Institute, an organization founded by a man who donated his wealth gained from oil to the improvement of agriculture, now finds itself a key player in the development of technologies that will ultimately lead to the replacement of oil with renewable and more environmentally friendly sources of energy.

What is more, this new technology will have major impacts on agriculture and agricultural production, not only through development of new biofuel crops, but also through the improvements to traditional agriculture that will come from understanding the molecular and genetic factors that determine crop yield and quality.