14 DAY TRIAL // A team of investigators led by scientists at the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) is currently working on developing an innovative enzyme, which they say could be used to create liquid fuel out of the dangerous greenhouse gas methane.
When released into the atmosphere, methane is 20 times more potent at fostering the greenhouse effect than carbon dioxide. As such, developing ways of putting it to good use, instead of simply releasing it into the air, could go a long way towards slowing down global warming.
The new investigation, funded through a $3.5 million (€2.6 million) grant by the DOE Advanced Research Projects Agency-Energy (ARPA-E), is spearheaded by biochemist Christer Jansson, who holds an appointment with the Berkeley Lab Earth Sciences Division (ESD).
“There’s a lot of methane available, and we want to develop a new way to harness it as an energy source for vehicles,” the team leader explains. Methane is produced by livestock such as cattle, natural gas, oil fields, wastewater treatment plants, and landfills around the world.
Methane can be turned into a liquid hydrocarbon even today, but that thermochemical process is non-selective, and requires vast amounts of energy to complete. This is why Jansson and his team are hoping to use methane-converting bacteria to create liquid fuel for transportation applications.
Methanotroph bacteria are able to break down methane by using a special enzyme. Unfortunately, this molecule is not as effective as it needs to be in order to enable large-scale fuel production. The Berkeley Lab-led team plans to focus its efforts on improving the actions of this specific enzyme.
At the same time, the group will also be studying an enzyme that usually converts CO2. This molecule is far better understood than its methane-gulping counterparts, and makes for an ideal platform to modify. Scientists now plan to modify it in such a way that it can be used for fuel synthesis.
The methylase-class enzyme can potentially be used to create both butanol and biodiesel fuels. The reactions need to take place inside a bioreactor, in the presence of gaseous methane. Before this can happen, the team needs to study the functional structure of the enzyme in 3D.
This will be done at the Advanced Light Source (ALS) facility, which is capable of producing light that combines X-ray diffraction and X-ray scattering imaging techniques. The ALS is generally used to study proteins in the human body, so that researchers can gain a deeper understanding of their structures.
“Once a functional methylase has been constructed, we need to engineer a new metabolic cycle that takes up methane and regenerates the co-substrate. Just like the Calvin-Benson cycle, but with assimilation of methane instead of carbon dioxide,” Jansson explains.
“This will take some time. But if we’re successful, the methylase can be installed into various microorganisms such as E. coli, yeast, and cyanobacteria and used on a large scale to produce liquid fuel from methane in natural gas or other sources,” the team leader concludes.