Professor Thomas Bobik and doctoral student David Gogerty invented a process for manufacturing isobutene (isobutylene) by identifying a new, natural enzyme that produces the fuel organically. (ISU/Bob Elbert)
A new bio-based method for producing a much-used fuel additive and industrial chemical, which is currently made from petroleum products, has been developed by an Iowa State University researcher.

Thomas Bobik, professor of biochemistry, biophysics, and molecular biology, invented a process for manufacturing isobutene (isobutylene) by identifying a new, natural enzyme that produces the fuel organically. Bobik and David Gogerty, a doctoral student working with him on the project, believe that once more research is completed, there could be huge benefits to the biofuels industry.

Bobik's enzyme makes it possible to convert the glucose found naturally in plants to make isobutene. The enzyme is found naturally in about half of all organisms in the world. While patent applications proceed, Bobik will not disclose the specific enzyme.

Isobutene is a gas used to produce chemicals and also in the manufacturing of fuel additives, adhesives, plastics, and synthetic rubber. It can be chemically converted to isooctane, which is a fuel that could be used to replace gasoline additive methyl tert-butyl ether (MBTE), which can be environmentally harmful.

Isooctane is used in gasoline to stop engine knocking and other problems. Currently, isooctane is produced from petroleum products.

Currently, one of the biggest expenses in producing the biofuel ethanol is the cost of separating the ethanol from the water where it's made. Bobik's new process will not include the cost of separation.

"Isobutene is a gas, so we can imagine that it will be easy to remove the isobutene from the vessel in which it was made, and that should be a very cheap and efficient way to purify the biofuel," said Bobik.

Though a drawback is that the process currently takes too long.

"The activity of the enzyme (in making the isobutene) is low," Bobik said. "It's too low for commercial application. So we're trying to use directed enzyme evolution to improve the activity of the enzyme so it can become commercially viable."

Directed enzyme evolution is the effort to engineer enzymes to perform certain functions. In this case, it is trying to find a way to get the enzyme to produce isobutene more quickly than in nature.

(Iowa State University)

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