The cattle industry is vital to Nebraska’s economy. According to the Nebraska Beef Council, there are four cows for every person in the state.
Cattle are also one of the top producers of methane, a greenhouse gas that has 25 times the effect on the climate that carbon dioxide does.
So, how does Nebraska reduce methane emission while not hurting its cattle industry-based economy? This is the question the University of Nebraska-Lincoln’s International Genetic Engineering Machines team (iGEM) is trying to answer.
The 2017 iGEM project aims to genetically engineer E. coli in a cow’s ruminal cavity to inhibit the methanogens (the microorganisms living in a cow’s ruminal cavity), and ultimately, methane gas being released into the atmosphere.
The students of iGEM chose this project because of the vital environmental effects it could have.
“I knew it was a problem, an environmental problem, and I wanted to see if it could be tackled,” said Nic Kite, a junior biochemistry major and iGEM member.
During their project, the team visited a farm in Ithaca, Nebraska, and the Nebraska Cattlemen in Lincoln to discuss their idea and found that many people in the cattle industry are supportive of having ‘green cows.’
“It’s the next push, as far as reducing methane,” said Jessica Harms, a sophomore chemical engineering major.
The methane released from cows originates from their plant-based diet, which is high in cellulose. The ruminant of a cow cannot break down cellulose itself and thus depends on its symbiotic relationship methanogens. The methanogens break down cellulose and the byproduct is methane gas.
“We’re going to try to reduce emissions in two ways, the first being bromoform and the second is nitrite reduction,” Kite said.
Harms discussed studies the team researched in which cows were fed a seaweed diet, which reduced methane emissions up to 70 percent. The key aspect that helped do so was the bromoform found in seaweed. When the cows were fed bromoform, the studies found cows coats and milk production improved.
In the bromoform method, the gene for bromoform was cloned from seaweed and put in E. coli, which can then be fed to cows and help reduce the release of methane.
The Nitrite reductase method works with the elements already present in a cow’s rumen.
“In the rumen, nitrate is already present. And so we try to reduce nitrate to nitrite, and that in turn reduces methane because it acts as a hydrogen sink,” said Tyler Barker, a junior computer engineering major.
The problem with this method is that it can cause nitrite build up which leads to methemoglobin in a cow’s bloodstream. Methemoglobin is unable to bind to oxygen in the bloodstream, so some tissues may not get the oxygen they need and, in some cases, can lead to death.
However, the iGEM team has also prepared for how to address a few worst case scenarios through “safety cases,” or “what if” scenarios.
“You have to think further, and that’s what we’re building our safety cases for; you think about how you can show this will be safe, and there’s lots of testing and validation to do this,” said iGEM faculty mentor, Myra Cohen.
One example of a safety case is the “kill switch” the team had to build into the genes to assure the E. coli could not live outside of the conditions in a cow’s rumen.
The iGEM team has completed their lab work and are now working on finalizing all of their research documents and data.
The iGEM team will represent their project at the 2017 iGEM Jamboree in Boston in November to present their findings and compete against other iGEM teams from around the country.