California ARB biofuel carbon intensity data for LCFS highlights diversity of ethanol pathways
US Army TARDEC showcased diesel series hybrid CERV in run-up to Indy 500

Bacterial enzyme converts carbon monoxide to hydrocarbons

Researchers at Utah State University report on an engineered bacterial enzyme—a molybdenum (Mo) nitrogenase—capable of converting carbon monoxide into usable hydrocarbons in a reaction similar to Fischer-Tropsch synthesis. A open access paper on their work appears in the Journal of Biological Chemistry.

Nitrogenase is the bacterial enzyme responsible for the biological reduction of N2 to ammonia (NH3), accounting for more than half of the input of fixed nitrogen into the biogeochemical N cycle, the authors note. Three different nitrogenases have been identified, with each being coded for by unique sets of genes; the nitrogenase system containing Mo is the most widely occurring and is preferentially expressed if sufficient Mo is present in the cell growth medium.

The Mo-dependent nitrogenase catalyzes the multi-electron reduction of protons and N2 to yield H2 and 2NH3. It also catalyzes the reduction of a number of non-physiological doubly and triply bonded small molecules (e.g., C2H2, N2O). Carbon monoxide (CO) is not reduced by the wild-type Mo-nitrogenase, but instead inhibits the reduction of all substrates catalyzed by nitrogenase except protons.

Here, we report that when the nitrogenase MoFe protein a-70 Val residue is substituted by alanine or glycine, the resulting variant proteins will catalyze the reduction and coupling of CO to form methane (CH4), ethane (C2H6), ethylene (C2H4), propene (C3H6), and propane (C3H8). The rates and ratios of hydrocarbon production from CO can be adjusted by changing the flux of electrons through nitrogenase, by substitution of other amino acids located near FeMo-cofactor, or by changing the partial pressure of CO. Increasing the partial pressure of CO shifted the product ratio in favor of the longer chain alkanes and alkenes.

—Yang et al.

The highest yielding product was ethylene, followed by propene, ethane, and propane.

This is pretty profound. Understanding this process paves the way for developing better ways of converting carbon monoxide, a toxic waste product of combustion, into transportation fuel and precursors for plastics—without the time and energy required for conventional extraction of fossil fuels.

—Lance Seefeldt, professor in USU’s Department of Chemistry and Biochemistry

The researchers also found that introduction of additional amino acid substitutions near FeMo-cofactor, along with an increased CO concentration, can significantly shift the product profile of nitrogenase CO reduction and condensation in favor of production of longer chain hydrocarbons. Thus, the team concludes, the Mo-nitrogenase offers an experimentally tractable system for examining mechanistic features that favor the production of longer chain hydrocarbons from CO that might be translated to the development of small molecule metal complexes that catalyze such reactions.

Like many waste-to-energy processes, we’ve found we can produce such hydrocarbons as propane and butane from carbon monoxide. But using this process, we may have the potential to produce such transportation fuels as diesel and gasoline that are readily adaptable to today’s vehicles.

— Zhi-Yong Yang


  • Zhi-Yong Yang, Dennis R. Dean, and Lance C. Seefeldt (2011) Molybdenum nitrogenase catalyzes the reduction and coupling of CO to form hydrocarbons J. Biol. Chem. doi: 10.1074/jbc.M111.229344



Reading this gave me a "holy crap!" reaction. Turning e.g. blast-furnace gas into electricity is no big deal. Capturing the CO and turning much of it straight into the major precursor of plastic monomers (ethylene) and the rest into other high-value products is a stunning coup. Doing it with cheap biological processes skips the water-gas shift and F-T processes needed to do it conventionally.

This puts garbage-to-materials much closer than it was before.



I´ll point to you that the concept is not really new, those guys are understanding and perfecting what nature and the agricultural sector has been doing for many years.

The energy balance as well as cost advantage of Brazilian sugar-cane derived ethanol relies heavily on BFN - Biological Fixation of Nitrogen. There are symbiotic microorganisms that "capture" nitrogen and enrich the plant [and the soil?] thus demanding less nitrogen fertilization, often derived from natural gas in a Haber-Bosch process.

This was developed by EMBRAPA the national research center for agricultural technology, and is known to everybody.

Many years ago when they were perfecting this and it was "news", the word was that it brought cost some 30% down, and for those EROI-fanatics, it also cleaned the fossil fuel usage in the energy balance sheet.

I see no reason US would not foster adoption of secure, sustainable, and environment friendly ways to nitrogen fertilize soil and biomass cultures with a bit of research.

Anyway, depending on how they perfect this, reducing nitrogen compounds is nearly as good as carbon compounds in fixing energy in chemical form. A bit explosive, but if handled adequately might be another excellent tool.

I have great hopes on this biochemical avenue.


I must correct myself.

Even though the use of Nitrogenase and it's ability as a catalyst to react N2 and H2 to form NH3 (to avoid Haber-Bosch) is not new, this intended use similar to Fischer-Tropsch is indeed something else.

While it's not clear exactly how it could be harnessed right now it opens up many possibilities both with synthetic biology and eventually with "plain" chemistry using what could be learned here.

There are some other interesting related links following , as well as searching for Nitrogenase or Nitrogen_fixation.


While not directly related, there is a very interesting work from Australian National University on a Closed loop thermochemical energy storage system using ammonia (

It uses N2, H2 and NH3 in a closed loop as a chemical storage and carrier of energy.

The comments to this entry are closed.