December 11, 2008

Research continues for modified lignin's potential as animal feed



The Agricultural Research Service (ARS) of the US Department of Agriculture is currently delved in unleashing lignin's potential in animal feed.


As cellulose is a key component of plant cell walls that can be converted into ethanol and other products, ARS is studying to make the conversion process easier but lignin is impeding cellulose conversion.


Plant walls contain cellulose, the main component of paper and a source of sugars for ethanol production. Cellulose could be described as the "brick" of the cell wall, while pectin, hemicellulose and lignin function like mortar, cementing everything together.


While lignin is vital for plant survival, the ARS is studying the alteration of lignin -- to break it down easier to facilitate the production of paper, ethanol and other industrial products, particularly of feed.


ARS scientists in the US Dairy Forage Research Center in Madison, Wiscosin are currently hard at work to modify the process. The team is composed of research agronomist John Grabber, ARS plant physiologist Ronald Hatfield, Fachuang Lu of the University of Wisconsin, and John Ralph, formerly with ARS and now at the University of Wisconsin.


Grabber and his colleagues first tested the effects of changing the cell walls in a laboratory--before applying those changes to live plants--by incorporating a chemical compound called coniferyl ferulate into lignin formed within cell walls. First, they synthesized the compound in the lab and added it to cell walls isolated from corn. Then they subjected the cell walls to alkaline treatments, which are commonly used to degrade lignin.


The altered lignin broke down more readily than conventional lignin under mild alkaline conditions, demonstrating the potential for this modification to facilitate cellulose use. Further research showed that incorporating other molecules such as feruloyl and caffeoylquinic acid into lignin could also enhance cellulose utilization. Hatfield, Ralph and ARS geneticist Jane Marita at Madison are now leading efforts to engineer plants to make lignin with coniferyl ferulate.

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