The increasing concentration of CO2 in the atmosphere has proved a major challenge to humans and the environment. For many years scientists have tried to develop methods to convert CO2 into a useful and environmentally safe product such as biofuel. Thus far they have been unsuccessful in developing an efficient method for the conversion.
However, a team of scientists has reverse engineered a natural pathway (photosynthesis) for CO2 fixation used by plants to convert CO2 into carbohydrates (mainly sugar) and at the same time releasing oxygen to the atmosphere. The researchers are from the Max Planck Institute (MPI) in Marburg, Germany, working in conjunction with scientists from the Lawrence Berkeley National Laboratory and the DNA synthesis expertise of the U.S. Department of Energy Joint Genome Institute (DOE JGI).
The team of researchers developed a new CO2-fixing enzyme that is 20 times faster than the enzymes found in nature to convert CO2 into sugar using sunlight. "We had seen how efforts to directly assemble synthetic pathways for CO2-fixation in a living organism did not succeed so far," said Tobias Erb of MPI, the leader of the study. "So we took a radically different, reductionist approach by assembling synthetic principal components in a bottom-up fashion in a test tube."
The researchers tried several theoretical CO2-fixation routes and decided to work with 17 different enzymes from 9 different organisms across life organism. They created a CO2-fixation pathway performance that is much faster than the process found in nature. "Now Berkeley Lab through the DOE JGI, has been a major contributor to our understanding of the vast genetic diversity of microorganisms and their roles in the environment, particularly in carbon cycling," said Yasuo Yoshikuni, the head of the DNA Synthesis Science group at the DOE JGI. "By sequencing underexplored phyla from ecologically important niches, we have homed in on the genes and pathways that we now are able to synthesize in the lab to unravel novel strategies that nature uses for carbon metabolism. Identifying these genes encoding CO2-fixing enzymes and their biological function is one of the important missing pieces in the climate puzzle."
This result opens the door for other future applications, according to Erb. "These could include the introduction of synthetic CO2-fixation cycles into organisms to bolster natural photosynthesis, or say, in combination with photovoltaics, lead the way to artificial photosynthesis, this might at the end jumpstart the design of self-sustaining, completely synthetic carbon metabolism in bacterial and algal systems."
This research was supported by the European Research Council, the Swiss National Science Foundation, the Swiss Federal Institute of Technology (ETH) in Zurich and the Max-Planck society.
The results of the study were published by Science magazine on November 18, 2017. A link to the article can be found here: http://science.sciencemag.org/content/354/6314/900