University of California, Irvine (UCI) molecular biologists have discovered an effective way to convert carbon dioxide (CO2) to carbon monoxide (CO). They use a novel approach involving a key enzyme that helps regulate global nitrogen that can be adapted for commercial applications like biofuel synthesis or synfuels.

Led by Yilin Hu, UCI assistant professor of molecular biology & biochemistry at the Ayala School of Biological Sciences, the researchers found that they could successfully express the reductase component of the nitrogenase enzyme alone in the bacterium Azotobacter vinelandii and directly use this bacterium to convert CO2 to CO.

Yilin Hu is an UCI assistant professor of molecular biology & biochemistry at the Ayala School of Biological Sciences.  Image Credit: UCI.  Click image for the largest view.

The intracellular environment of the bacterium was shown to favor the conversion of CO2 in a way that would be more applicable to the future development of strategies for large-scale production of CO. The findings were surprising to the group, as nitrogenase was only previously believed to convert nitrogen (N2) to ammonia (NH3) within the bacterium under similar conditions.

The full study has been published in Nature Chemical Biology.

Hu and her colleagues knew that the intracellular environment of the bacterium Azotobacter vinelandii favors other reduction reactions, due in part to its well-known oxygen protection mechanisms and presence of physiological electron donors. But they were unsure if the intracellular environment would support the conversion of CO2 to CO.

They were excited to discover that the bacterium could reduce CO2 and release CO as a product, which makes it an attractive whole-cell system that could be explored further for new ways of recycling atmospheric CO2 into biofuels and other commercial chemical products. These findings of Hu’s group establish the nitrogenase enzyme as a fascinating template for developing approaches to energy-efficient and environmentally-friendly fuel production.

HU said, “Our observation that a bacterium can convert CO2 to CO opens up new avenues for biotechnological adaptation of this reaction into a process that effectively recycles the greenhouse gas into the starting material for biofuel synthesis that will help us simultaneously combat two major challenges we face nowadays: global warming and energy shortages.”

The organic approach using organisms is well underway particularly with ethanol and methanol. These use the CO2 directly without the step to CO. This new path may well have legs, but its going to have to grow them. The organic route horses are out of the barn, harnessed up and hard at work.

There should be a path here. Some industrial combustion currently spends a great deal of investment and operating expense in CO to CO2 conversion. Going the other way with this technology may have a potential we haven’t considered yet with a synfuel income potential instead of a hard cost.


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