Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at the Korea Advanced Institute of Science and Technology (KAIST) has reported, for the first time, the development of a novel strategy for microbial gasoline production through the metabolic engineering of E. coli bacteria.
The Institute’s scientists succeeded in producing 580 mg of gasoline per liter of cultured broth by converting the in vivo generated fatty acid.
For decades industry used fossil resources to produce liquid fuels such as gasoline, diesel, and many industrial and consumer chemicals for daily use. But the increasing effort and costs to find natural resources as well as the environmental issues have triggered a strong interest in developing sustainable ways to obtain fuels and chemicals.
Gasoline, the petroleum-derived product that is most widely used as a fuel for transportation, is a mixture of hydrocarbons, additives, and blending agents. The hydrocarbons, called alkanes, consist only of carbon and hydrogen atoms. Gasoline has a combination of straight-chain and branched-chain alkanes (hydrocarbons) consisting of 4-12 carbon atoms linked by direct carbon-carbon bonds.
Previously, through metabolic engineering of Escherichia coli (E. coli), there have been a few research results on the production of long-chain alkanes, which consist of 13-17 carbon atoms, suitable for replacing diesel fuel.
But there has been no report until this week on the microbial production of short-chain alkanes as possible substitutes for gasoline.
The paper reports on the development of a novel strategy for microbial gasoline production through metabolic engineering of E. coli.
The research team engineered the fatty acid metabolism to provide the fatty acid derivatives that are shorter than normal intracellular fatty acid metabolites, and introduced a novel synthetic pathway for the biosynthesis of short-chain alkanes. This allowed the development of platform E. coli strain capable of producing gasoline. Additionally the platform strain, if desired, can be modified to produce other products such as short-chain fatty esters and short-chain fatty alcohols.
The Korean researchers describe in the paper detailed strategies for 1) screening of enzymes associated with the production of fatty acids, 2) engineering of enzymes and fatty acid biosynthetic pathways to concentrate carbon flux towards the short-chain fatty acid production, and 3) converting short-chain fatty acids to their corresponding alkanes (gasoline) by introducing a novel synthetic pathway and optimization of culture conditions. The research team also showed the possibility of producing fatty esters and alcohols by introducing responsible enzymes into the same platform strain.
Professor Sang Yup Lee said, “It is only the beginning of the work towards sustainable production of a green gasoline. The titer (a way of expressing concentration) is rather low due to the low metabolic flux towards the formation of short-chain fatty acids and their derivatives. We are currently working on increasing the titer, yield and productivity of bio-gasoline. Nonetheless, we are pleased to report, for the first time, the production of gasoline through the metabolic engineering of E. coli, which we hope will serve as a basis for the metabolic engineering of microorganisms to produce fuels and chemicals from renewable resources.”
The amazing thing is the incredible versatility of E, coli. Congratulations are in order for the getting the gasoline product coaxed out of the genetic code. It’s a good day for the energy density of gasoline products for consumers. It’s also a worth a note that the E. coli sourced gasoline would (should) satisfy the green crowd’s demand for a renewable source of transport fuel. Lets hope the path to commercial scale isn’t long and torturous and we see a gradual shift to an unending supply of motor fuel.