The main issue that the scientists have confronted so far when trying to get ethanol out of switchgrass has been the high amount of lignin it contains. On the other hand, lignin is beneficial for the plant’s natural growth and plays an important role in its defense system, but interferes with the fermentation process that produces biofuels, says Zeng Yu Wang of The Samuel Roberts Noble Foundation in Ardmore, Oklahoma.
Lignin has been found to contribute to the plant’s “recalcitrance,” which has the role of protecting it from insects, fungus and the weather. “Recalcitrance, or a plant’s natural defenses against insects, fungus and the weather, is widely acknowledged as being the single biggest barrier to the production of biofuel and biochemicals from switchgrass and other lignocellulosic materials,” said Jonathan Mielenz, a co-author and member of the Department of Energy lab’s BioEnergy Science Center.
Based on the experience they had gathered with plants like alfalfa, the scientists decreased the caffeic acid 3-O-methyltransferase, or COMT, gene in the Alamo variety of switchgrass, thus decreasing the amount of lignin by one eigth.
“The transgenic lines require lower temperature preprocessing and only one-quarter to one-third the level of enzymes for equivalent ethanol fermentation compared to the unmodified switchgrass. This significantly lowers the cost of biofuels and biochemicals from this switchgrass,” says Wang. The change could also increase the quantity of ethanol produced from the same amount of switchgrass by one third.
Producing cheaper bioethanol could eventually lower the overall carbon dioxide emissions involved in the process and could also affect the price, positively. What I don’t agree, though, is the easiness that the scientists genetically modify the plants with. That could also affect the entire ecosystem, and I guess that’s the last thing anyone could wish.
