Researchers engineer bacteria to turn carbon dioxide into liquid fuel

Researchers engineer bacteria to turn carbon dioxide into liquid fuel
Genetically engineered strains of the cyanobacterium Synechococcus elongatus in a Petri dish

( -- The genetically modified cyanobacterium consumes carbon dioxide and produces the liquid fuel isobutanol by using energy from sunlight.

Global climate change has prompted efforts to drastically reduce emissions of , a greenhouse gas produced by burning fossil fuels.

In a new approach, researchers from the UCLA Henry Samueli School of Engineering and Applied Science have genetically modified a cyanobacterium to consume carbon dioxide and produce the liquid fuel isobutanol, which holds great potential as a alternative. The reaction is powered directly by energy from sunlight, through photosynthesis.

The research appears in the Dec. 9 print edition of the journal Nature Biotechnology and is available online.

This new method has two advantages for the long-term, global-scale goal of achieving a cleaner and greener energy economy, the researchers say. First, it recycles carbon dioxide, reducing greenhouse gas emissions resulting from the burning of . Second, it uses solar energy to convert the carbon dioxide into a liquid fuel that can be used in the existing , including in most automobiles.

While other alternatives to gasoline include deriving biofuels from plants or from algae, both of these processes require several intermediate steps before refinement into usable fuels.

"This new approach avoids the need for biomass deconstruction, either in the case of cellulosic biomass or algal biomass, which is a major economic barrier for biofuel production," said team leader James C. Liao, Chancellor's Professor of Chemical and Biomolecular Engineering at UCLA and associate director of the UCLA-Department of Energy Institute for Genomics and Proteomics. "Therefore, this is potentially much more efficient and less expensive than the current approach."

Researchers engineer bacteria to turn carbon dioxide into liquid fuel
Synechococcus elongatus in a flask. Genetically engineered strains of the cyanobacterium Synechococcus elongatus in a flask

Using the cyanobacterium Synechoccus elongatus, researchers first genetically increased the quantity of the carbon dioxide-fixing enzyme RuBisCO. Then they spliced genes from other microorganisms to engineer a strain that intakes carbon dioxide and sunlight and produces isobutyraldehyde gas. The low boiling point and high vapor pressure of the gas allows it to easily be stripped from the system.

The engineered bacteria can produce isobutanol directly, but researchers say it is currently easier to use an existing and relatively inexpensive chemical catalysis process to convert isobutyraldehyde gas to isobutanol, as well as other useful petroleum-based products.

In addition to Liao, the research team included lead author Shota Atsumi, a former UCLA postdoctoral scholar now on the UC Davis faculty, and UCLA postdoctoral scholar Wendy Higashide.

An ideal place for this system would be next to existing power plants that emit carbon dioxide, the researchers say, potentially allowing the to be captured and directly recycled into .

"We are continuing to improve the rate and yield of the production," Liao said. "Other obstacles include the efficiency of light distribution and reduction of bioreactor cost. We are working on solutions to these problems."

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Provided by University of California Los Angeles (news : web)

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Dec 10, 2009
One problem-what if this cyanobacteria escapes into the environment- instant toxic pollution. Wonder if any provision has been made to make it completely non-viable outside of the industrial setting?

Dec 10, 2009
Do you know what the species Synechococcus elongatus is? I hate to tell you this, but it already has escaped into the environment, in pretty large quantities, in marine and freshwaters. I understand we are talking about a microbe with an altered genome, but regardless, due to the pathogen of the original strain, I don't think even an altered genome of this species would pose a significant biohazard. It's more likely that the altered strain's production of isobutyraldehyde gas would be the most threatening consequence, and this effect, I'm sure, would be just as regulated as any other fuel producing industry. Bottom line, if these microbes "escape" we won't turn into zombies or our skin start to fall off.

Dec 10, 2009
What happens to all the plant life that needs that CO2

Dec 10, 2009
Plant life seemed to do fine before the industrial revolution, I'm sure using our CO2 emissions won't effect plants too much.

Dec 10, 2009
It is not like it will use all of the CO2

Dec 10, 2009
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Dec 10, 2009
I wonder if they figured this into their simulations of global warming?

Dec 11, 2009
I would think that this specific technology is still to recent to have been figured into simulations of global warming. Although I would guess that there are simulations out there where they have modeled carbon capture in general, but no specific technology.

Dec 11, 2009
What's missing is how much isobutanol per square meter and day can be harvested from such a setup.

Unfortunately this is not a volumetric process since the bacteria require sunlight...if we could get them to use heat as an energy source then things might be a lot better. So I'm not too optimistic about the large scale applicability of this.

Dec 11, 2009
This article plus the other about bigger pores on plants equal "let's use up CO2 (and make fuel in the process)"

I will seriously lol when the day CO2 levels start getting too low and we get a whole new climate change problem.

Dec 11, 2009
This does not use up any CO2 (neither does any other process for converting CO2 into fuel)

CO2 is used by the bacteria to create isobutanol which is then colected and burned as fuel (releasing water and CO2 as end products)

The advantage is that it doesn't put any MORE CO2 in the atmosphere (like burning fossil fuels does). The described process is a zero sum game. We're not taking any CO2 away from plants (where did that ludicrous idea ever come from?)

The only process that would get rid of CO2 would be sequestration - and we could sequester at a pretty good clip for a few thousand years without making much of a dent in the global CO2 balance.

Dec 11, 2009
Funny isn't it. So many discussions about whether the CO2 excess is not manmade, but when we start looking at using the excess to produce new fuel sources, people get worried that we will suffocate the plants ...

It is the soil transmitted minerals the plants use to grow that they are growing short of, not CO2 ... there's more than enough for everyone.

If this CO2 extraction method produces a motor fuel ... excellent. If it is not potent enough for fuel, can it be used for other oil based manufacturing processes for plastics, drugs, lubricants, beauty products?

We have to offset peak oil as well as save the environment. The economy is one of the cornerstones of our modern global society and we have to mitigate as much of our oil dependence as possible, by replacing (or spreading) the dependence across many alternative sources.

Dec 11, 2009
No. This tech delays nothing. It takes CO2 out of the atmosphere which is put back when the isobutanol is used as fuels. There is no gain or loss of CO2 anywhere.

As for CO2 to diamonds: Sure you can do this (it's not particularly hard). However this requires more energy than you got out of producing the CO2 in the first place (and no, you can't fudge this energy balance with 'clever ingenuity' because that would mean that you have invented a perpetuum mobile)

Dec 11, 2009
danlgarmstrong: If the beaches were covered in diamonds they would be worth nothing. They only have a value at all because they are artificially made scarce.

Dec 11, 2009
antialias: I suggest you start sequestrating pretty damn quick while you can. The real problem is the need for automotive fuels in the first place. Rid the cars, scrap the planes and all the problems go away, assuming of course its not allready too late.

Dec 11, 2009
Ant: How do the problems go away if we ban all cars/planes? The CO2 is in the atmosphere now. This tech (if it works on a large scale - which I'm not convinced it does) could reduce use of fossil fuels. A much needed first step. Let's start thinking of how we can be carbon neutral before we go for sequestration - makes more sense.

I'm not looking for money - diamond beaches would look pretty!

But you wouldn't want to lie down on them. I'll stick with sand.

We pull too much CO2 out of the atmosphere we might change the climate in the opposite direction

Unlikely as we are nearing the top end of our buffer system's capability to take up excess CO2. If we start pulling CO2 from the atmosphere (something this tech does NOT do since the CO2 is released again when you use the fuel) then the buffer systems will compensate from a long time before we notice a dip in CO2 concentration.

Dec 11, 2009
An application that I would like to hear something about is the mixing of charcoal into soil, which has been shown to have a huge positive impact on soil fertility, as well as being, to some extent, self-perpetuating. This technology was empoyed by natives of the Amazon Basin to enrich the low-nutrient laterite soils prevalent there to be able to increase agricultural yield, just in the past few hundred years. Why not find a way to convert "scrubbed" carbon into charcoal for this agricultural use? Kills many birds with a single stone.

Dec 12, 2009
You mean:
- digging up coal (at an energy cost)
- burn coal for energy
- taking CO2 out of the air in an energy intensive process (read: one that is more energy intensive than the energy you got out of burning the coal in the first place because otherwise you would just have invented a perpetuum mobile since you could then reburn the coal)
- reburying it into the ground

That makes sense...not.

Dec 12, 2009
As soon as any article mentions "Global Warming", it's like having 20 I.Q. points suddenly vanish.
One of the reasons I feel GW is such BS is because of the obvious lies / misunderstandings in just about every "Green" article.

It will obviously take more energy to grow that pond scum to absorb the CO2 then what energy was generated by burning coal. Unless you waste huge tracts of land growing it using Sunlight.

What interest and science there was in this article got destroyed by a non-sense "Green" slant.

Dec 12, 2009
Tyrannical: I'm not sure it'd be considered a waste of huge tracts of land--it depends how efficient the bacteria are. As it is, you could turn these critters into, basically, organic solar panels (oodles of engineering involved, I know, but I should imagine that it would be possible to implement) that produce isobutanol instead of electricity. I'd be somewhat surprised if it was a more efficient source of energy than normal inorganic solar panels, but there is the added advantage that the process can be used either to generate energy or sequester CO2 (get carbon into a higher-energy form, and it's easier to go from there to some kind of solid or liquid that can be safely sequestered away). Of course, they'd require plenty of water to do their thing, so...maybe you're right after all. Depends on the energy and resource balance relative to other ways of harnessing sunlight for energy and sequestering CO2. The versatility's attractive, though, I must say.

Dec 14, 2009
My imagination gives me the image of some genius that figures out how to turn the CO2 in the air into diamond. Imagine diamond sand covering the beaches. Imagine all buildings with diamond sheathing. Imagine snow in Los Angeles.

Hmm...there is possibly a high-pressure phase of CO2 that might just be metastable at ambient pressure, like diamond. However, you would need to put a lot of energy into it to change the phase, just like with diamond.

Dec 14, 2009
Whenever I see plans for some sort of CO2 sequestration in gaseous form I always think of the Lake Nyos tragedy in Cameroon (and what a potential for disaster such sequestration in populated areas could be if the containment were to be breached by earthquake or simply disrepair by future generations)

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