Scientists are working towards harnessing a particular skill exemplified by cows' stomachs - breaking down plant cellulose - to improve biofuel production.
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ADELAIDE: The microbial mix inside a cow's stomach has revealed genetic clues to more efficiently turn grass into ethanol biofuel, according to scientists in the U.S. who have carried out an unprecedented scale of genetic sequencing.
The research, published in the journal Science, used a supercomputer to identify new enzymes from a sample size of millions, expanding the known catalogue of genes and genomes that can break down cellulose.
“My colleagues and I could assemble these tiny pieces of DNA and verify both experimentally and with alternative computational methods that what we had was a real picture,” said lead author Matthias Hess from Washington State University. “This would not have been possible five years ago.”
Harnessing the cows' expertise
Inside a cow's rumen - one of the four compartments of its stomach - dwells a complex community of bacteria. Evolved over thousands of years, they turn otherwise indigestible plant cellulose into sweeter, simpler sugars and other products. This is the first and hardest step in creating cellulosic biofuel.
To learn how to do the same, scientists placed nylon sacks full of switchgrass – a tough, fast-growing native American grass - through a hole in the cow's skin into the stomach.
After 72 hours they removed the grass, along with bacteria in the midst of a digestion frenzy, and analysed them as a group using metagenomics. “Metagenomics means analysis of DNA taken directly from environmental samples,” said Hess.
How to find elusive bacteria
As only about 1.5% of bacteria found in nature can be cultured, this technique allows crucial research to be carried out on the majority that resist cultivation in the lab.
The result was 270 billion base pairs of genetic code, almost a hundred times more than the human genome, and an estimated two million potential genes to be investigated.
To find which bacteria could digest cellulose, the researchers compared codes with known regions of Carbohydrate Active Enzymes called CAZymes. “Regions include domains that bind cellulose or facilitate cellulolytic activity,” Hess described.
Upping the potential of switchgrass
Having identified over 25,000 genes with the right regions, they produced almost a hundred potential CAZymes for testing. Over half could break cellulose into simple sugars.
For years switchgrass has been grown for biofuel production, as it can yield 540% more energy than is needed for it to grow.
Every tonne can produce 300 litres of ethanol, and it is inedible and resistant to pests, flooding and drought, making it a good candidate for biofuel production.
Ethanol Biofuel from a Cow's Stomach
Very interesting article. I hope they can develop the technology to harness this energy source as soon as possible.