Modified Lignin Has Potential Benefits for
Ethanol, Paper and Feed By
Laura McGinnis December 9, 2008
Cellulose is a key component of plant cell walls that can be converted
into ethanol and other products. New findings from the
Agricultural Research Service (ARS) could
help make that conversion process easier.
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.
Lignin is vital for plant survival, but its structure impedes
cellulose conversion. But what if lignin were altered so that it would break
down easier, thus facilitating the production of paper, ethanol and other
That's the goal of ARS scientists at the
Dairy Forage Research Center in Madison, Wis. There, research agronomist
Grabber--working with ARS plant physiologist
Hatfield, Fachuang Lu of the University of
Wisconsin, and John Ralph, formerly with ARS and now at the University of
Wisconsin--has designed lignin that breaks down more easily.
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
Marita at Madison are now leading efforts to engineer plants to make lignin
with coniferyl ferulate.
This work has potential benefits not just for paper and ethanol
production, but also for livestock production. Modified lignin could make
fibrous crops more digestible, allowing producers to feed more forage crops and
less grain to their livestock.
ARS is a scientific research agency of the
U.S. Department of