Developing alternative fuels from plants has been challenging in part due to the high costs associated with processing plant biomass to more easily convert it into sugars and from there into biofuels. Ruminants such as the cow, however, can eat more than a hundred pounds of plant matter a day and break it down.
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Switchgrass decomposing inside the cow rumen. (Image by Damon Tighe, DOE JGI)
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Seeking to harness this ability, researchers at the DOE JGI and the Energy Biosciences Institute (EBI) applied massive-scale DNA sequencing to characterize genes and genomes of plant-digesting microbes isolated from 270 billion bases of sequence generated from the cow rumen.
“Microbes have evolved over millions of years to efficiently degrade recalcitrant biomass,” said JGI Director Eddy Rubin, a lead on the study published in the January 28, 2011 issue of Science. “[They’ve solved] this challenge, overcoming the plant’s protective armor to secure nutrients, the rich energy source that enables them and the cow to thrive.”
Rubin’s postdoctoral fellows Matthias Hess, now an assistant professor at Washington State University TriCities, and Alex Sczyrba used the promising bioenergy crop switchgrass and teamed with colleagues at the University of Illinois to work with the fistulated cow model, identifying nearly 30,000 genes that encode enzymes which can break down cellulose and other plant polysaccharides into small sugars.
The team noted that a significant faction of the 30,000 genes identified are indeed active against plant material and would be a treasure trove of novel enzymes for biofuel researchers.