Cows may hold the key to advancing production of second generation biofuels as scientists from the University of Illinois and Washington State University discover new enzymes in the bovine rumen that effectively breakdown switchgrass, a prime feedstock for bioenergy.
The bovine rumen is the cow's primary grass digestion chamber. This chamber holds a range of organisms such as fungi, bacteria, archaea, protista and viruses which process all food matter that pass through the rumen.
In a new study, the scientists recorded their research on the different enzymes within the rumen which they believe can be used to advance the conversion of non-food feedstock into bioenergy sources. "The problem with second-generation biofuels is the problem of unlocking the soluble fermentable sugars that are in the plant cell wall," said Roderick Mackie, a professor of animal sciences at the University of Illinois. "The cows been doing that for millions of years. And we want to examine the mechanisms that the cow uses to find enzymes for application in the biofuels industry," he explained. This new study builds on previous studies conducted by Mr. Mackie and research partner Matthias Hess, a professor at the Washington State University.
In previous studies, the scientists applied a proven technique for studying ruminant nutrition. They placed mesh bags holding small volumes of alfalfa or switchgrass into the cow rumen through a permanent, surgically installed portal and examined the microbes that attached to each plant type after two to three days. Through visual and chemical assessment, the scientists observed that microbes in the rumen were efficiently processing both types of plant matter. They determined that different communities of microbes were attracted to each plant type.
In their latest study, the researchers incubated switchgrass in the cow rumen for 72 hours. After the incubation period, they conducted an analysis of all the rumen microbes that were attached to the switchgrass - a population sample consisting of 270 billion letters of the DNA code.
The analysis by was led by Edward Rubin of the Department of Energy Joint Genome Institute and the Lawrence Berkeley National Laboratory. Using specific filters, the researchers reduced the number to 27,755 potential carbohydrate-active genes. These genes have been identified for their ability to break down plant polysaccharides into small sugars. The scientists then cloned some of these genes into bacteria, successfully producing 90 proteins of interest. Among the candidate proteins, they discovered that 57 percent were capable of processing cellulose and almost 20 percent were capable of breaking down real-world switchgrass.
This confirms their theory that a significant fraction of the carbohydrate-active genes are active against plant material. Additionally, the scientists believe these genes could hold a large amount of new enzymes for biofuel researchers. The research team comprised members from the Joint Genome Institute, the University of California at Berkeley and biotechnology company Illumina Inc. The Energy Biosciences Institute funded the research.
source: APEC-VC Korea