Gasoline from the air

Vanadium nitrogenase, an enzyme found in soybean roots, may be the key to air-conditioned cars in the near future.

Propane molecule structure. (Photo: Bloomberg)

This enzyme, which normally produces ammonia from nitrogen, is also capable of converting carbon monoxide (CO) to propane, a gas used for cooking in kitchens. Although it is only in its early stages, scientists say the study could eventually lead to new ways to produce fuel from the air.

The organism studied here is Azotobacter vinelandii, a strain of bacteria of economic importance. Azotobacter vinelandii is found in the soil around the roots of nitrogen fixation plants such as soy. Farmers love to plant Azotobacter vinelandii because it uses an enzyme system to turn atmospheric nitrogen into unusable ammonia and other substances. And other crops can use those chemicals to grow.

Markus Ribbe, of the University of California, Irvine, co-authored a study published in the journal Science Ribbe - and colleagues have isolated a particular enzyme called vanadium nitrogenase to convert nitrogen into ammonia. They then separate the nitrogen and oxygen that the enzyme uses, and fill the vacancy with CO. Without nitrogen and oxygen, the enzyme starts turning CO into a short carbon chain with two and three atoms. The main carbon chain is propane.

In terms of science, the new function of Vanadium nitrogenase is a 'profoundly meaningful discovery , ' said Jonas Peters, a California-based scientist. Ribbe and his colleagues may have many important industrial applications: 'Clearly, this finding could lead to new ways to produce synthetic liquid fuels if we can create longer carbon chains' . If everything goes well, this technique can help cars run on their own emissions.

According to Ribbe and Peters, the current challenge is to extract Vanadium nitrogenase. Scientific fact has long been known about this enzyme because of its importance in agriculture. Researchers have even isolated the genes encoding Vanadium nitrogenase more than 20 years ago. However, the technology of extracting, cultivating and storing large amounts of this enzyme has only developed in the last few years, so this research can be promoted.