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Home » Atmosphere, BioChemicals/Renewable Chemicals, Business News/Analysis, Carbon Dioxide (CO2), Feedstocks, Opinions, Process, R & D Focus

The Three Microb-eteers: Methanogens, Methanotrophs, Acetogens and Knallgas Bacteria

Submitted by on July 31, 2015 – 3:44 pmNo Comment

by Jim Lane (Biofuels Digest)  Which microbes achieve a better, faster, cheaper transformation of the world around us?  …  Down there in the mud, too small to be seen with the naked eye, are some of your new best friends. Some of the most colorful and transformative little varmints that, tiny as they are, can do astonishing things when it comes to turning basic molecules like hydrogen, oxygen and carbon into the building blocks and consumables of our civilization.


These guys consume hydrogen and carbon dioxide and produce methane. You’ll find them described in many cases as “gut bacteria” and just about any animal producing methane through rumination or digestion has a boat-load of them.

Turns out, methanogens can produce, under the right stress conditions, a whole bunch of useful bioproducts in addition to methane.

Accordingly, over the eons, they have developed their own coping strategies. One way of doing so is to accumulate some small, soluble organic molecules inside the cell. Defenders of the realm, you might call them.

One group just happens to be the alpha amino acids— such as lysine, methionine and threonine. Which just happen to be essential to healthy people, and also healthy cows and chickens. And just happen to be something that animal protein is relatively replete with, but vegetable protein is not.

Meaning that, if you feed a steady diet of veggie protein instead of animal protein to someone you love or a farm animal, it comes in handy to have an amino acid supplement if growth or milk production is on your agenda. And you may have heard that farmers supplement dairy feed with lysine.

Yes! you have cried. What if we could train up some friendly archaea methanogens to make industrially feasible concentrations of amino acids, as a byproduct along with the methane we usually get from them?

Yes! Then feed that to farm animals to improve their diet, thereby making it possible to use lower-cost veggie rations such as corn grain.

Because Jay Kouba and his team at Trelys already had the same idea, and are busy getting down the road with it. They’ve picked up early-stage investment from Arch Venture Partners and First Green Partners — with amino acids in early focus, and a whole bunch of products in the potential mix. Food, polymers, feed, chemical intermediates, lubricants and fuels. Much more on Trelys here.


So, if a methanogen eats hydrogen and CO2 and produces methane along with other things, a methanotroph eats methane and oxygen.

With this little microbe you can take methane and make it right back into the very food that the cows ate to produce waste sludge in the first place.

Now, before you can say “medieval alchemy”, let’s declare affirmatively that only a few companies are getting materially down the road with methanotrophic technology. Calysta, Mango Materials and Industrial Microbes among them — all of them are early-stage, no one has built a plant yet.


If you can say “LanzaTech” and ring a bell somewhere in your mind, then you already know something about acetogens. What does an acetogen eat? Unlike methanogens that eat hydrogen and carbon dioxide, these critters naturally gravitate towards a diet of hydrogen and carbon monoxide.

Acetogens were names for their ability to produce acetic acid, and can be trained to produce ethanol.

In the new bioeconomy, where there’s smoke, there’s spandex

Acetogens, as it happens, can make some amazing things beside the dread alcohol fuel.

There are other companies using acetogens with that interesting property of being able to ferment a carbon monoxide gas. ZeaChem is one, INEOS Bio is another.

They drag CO2 from the atmosphere, which is then converted into fuels and chemicals, some of that volume becomes CO2 when you burn the fuel (but not all, it can also be sequestered in chemicals), and that CO2 is reabsorbed by the trees. The carbon-neutral cycle, in a nutshell, which is why these technologies can have extravagant 70-90 greenhouse gas emission savings compared to baseline gasoline.

Knallgas bacteria

There’s the hydrogen and oxygen type, and then there’s the hydrogen and CO2 type (similar to methanogens). And they make a valuable gas, which contains energy.

As a note from the Berkeley Lab mentions, “R. eutropha and other Knallgas bacteria oxidize hydrogen under aerobic conditions and are ideal candidates for production of Electrofuels, the focus of a Department of Energy ARPA-E program for research on microorganisms that can produce liquid fuels without using petroleum or biomass. ARPA-E estimates that that electrofuels technology has the potential to be ten times more efficient than methods that rely on biomass.  READ MORE

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