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Researchers Modify Microbe to Produce Non-Crystalline Cellulose for Use in Biofuel Production
23 April 2008
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| Left: Two rod-shaped, wild type cyanobacteria. Right: A genetically altered cyanobacterium that produced highly visible cellulose (marked by cellulase coupled with an electron dense gold marker). Click to enlarge. Credit: Brown and Nobles, UT Austin |
Scientists at The University of Texas at Austin have modified a photosynthetic microbe (Synechococcus leopoliensis strain UTCC 100, a cyanobacterium) to produce non-crystalline cellulose which can be used as a feedstock for producing ethanol and other biofuels. A paper on the research is published in the journal Cellulose.
Professor R. Malcolm Brown Jr. and Dr. David Nobles Jr. modified the cyanobacterium (also known as blue-green algae) by transferring cellulose synthesis genes from Gluconacetobacter xylinus, a prolific cellulose producer. The cellulose produced by the modified cyanobacterium is in a relatively pure, gel-like form that can be broken down easily into glucose. The cyanobacteria also directly produce large amounts of glucose or sucrose.
The problem with cellulose harvested from plants is that it’s difficult to break down because it’s highly crystalline and mixed with lignins [for structure] and other compounds. The huge expense in making cellulosic ethanol and biofuels is in using enzymes and mechanical methods to break cellulose down. Using the cyanobacteria escapes these expensive processes.
The cyanobacterium is potentially a very inexpensive source for sugars to use for ethanol and designer fuels.
—David Nobles
The cyanobacteria developed by can be grown in production facilities on non-agricultural lands using salty water unsuitable for human consumption or crops.
The glucose, cellulose and sucrose can be continually harvested without harming or destroying the cyanobacteria. Harvesting cellulose and sugars from true algae or crops, like corn and sugarcane, requires killing the organisms and using enzymes and mechanical methods to extract the sugars.
Brown and Nobles calculate that the approximate area needed to produce ethanol with corn to fuel all US transportation needs would be around 820,000 square miles, an area almost the size of the entire Midwest.
They hypothesize they could produce an equal amount of ethanol using an area half that size with the cyanobacteria based on current levels of productivity in the lab, but they caution that there is a lot of work ahead before cyanobacteria can provide such fuel in the field.
Work with laboratory scale photobioreactors has shown the potential for a 17-fold increase in productivity. If this can be achieved in the field and on a large scale, only 3.5% of the area growing corn could be used for cyanobacterial biofuels.
The pressure is on all these corn farmers to produce corn for non-food sources. That same demand, for sucrose, is now being put on Brazil to open up more of the Amazon rainforest to produce more sugarcane for our growing energy needs. We don’t want to do that. You’ll never get the forests back.
—R. Malcolm Brown
Resources
David R. Nobles Jr. and R. M. Brown Jr. (2008) Transgenic expression of Gluconacetobacter xylinus strain ATCC 53582 cellulose synthase genes in the cyanobacterium Synechococcus leopoliensis strain UTCC 100; Cellulose DOI: 10.1007/s10570-008-9217-5
April 23, 2008 in Biotech, Fuels | Permalink | Comments (17) | TrackBack (0)
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Comments
17-fold increase? Wow!
Posted by: Cervus | Apr 23, 2008 11:23:41 AM
On first read, this was more positive than it really is. But we can at least add it to the growing pile of potentially revolutionary biofuel tech. Unfortunately it's a big If, assuming they can achieve the increase on a commercial scale.
Posted by: Cervus | Apr 23, 2008 11:31:52 AM
The economics are perhaps better than for normal algae but the technical difficulties would be greater than for normal algae farming - and they haven't got that sorted yet. For example how do you keep the strain pure?
Posted by: DavidJ | Apr 23, 2008 11:53:18 AM
"...the research is published in the journal Cellulose."
The fact that there is a journal named Cellulose should tell us that this topic is front and center.
Posted by: sjc | Apr 23, 2008 11:57:26 AM
@ DavidJ -
you use closed-loop bioreactors.
Posted by: Rafael Seidl | Apr 23, 2008 1:32:36 PM
From what I've read lately GreenFuel and other companies have discarded the rigid bioreactors and are going with plastic bags instead. The cost issues might still be insurmountable, though when oil doubles in price again, who knows?
Posted by: Cervus | Apr 23, 2008 2:06:23 PM
The long plastic bag tubes seem to offer many advantages over rigid bioreactors. Primarily, they flatten out to maximize sun light capture and growth, while minimizing costs. It does seem inevitable that salt water will leak, so you might not want to use them on land you hoped to use for crops at a later time.
Since they need salt water, that 3.5% of 820,000 square miles (28,700 square miles) that's not good for much else had better be near the coasts. Sounds like Texas to me.
My guess is lots of other organisms will find this cyanobacteria yummy, so it would not be very competitive if it (when it) escapes.
They didn't say if this produces lipids. Are we talking biodiesel too?
Posted by: Healthy Breaze | Apr 23, 2008 3:27:11 PM
cool
Posted by: Paul | Apr 23, 2008 4:09:00 PM
There are so many bio-fuel strategies/enzymes/bacteria/algae out there, I've lost track.
Posted by: Neil | Apr 23, 2008 4:55:45 PM
I was reading where Branson wants to use algae to make jet fuel. He had used a bio diesel blends in the first tests and has had some interest in ethanol as well.
http://www.msnbc.msn.com/id/23455499/
Posted by: SJC | Apr 23, 2008 6:20:17 PM
I'm keeping a close eye on PetroSun. They supposedly started up a pilot plant in Texas for algae-based fuels this month. If they succeed, they'll be the next Exxon or Chevron. Bring it on.
Posted by: Cervus | Apr 23, 2008 6:29:41 PM
Anyone who has had a saltwater aquarium knows how prolific and blasted hard to kill cyano is. If it can be turned from the Dark Side of the Force, I'd be dancing in the streets.
Posted by: Tagamet | Apr 23, 2008 8:32:21 PM
I wonder what would happen if you accidentally ingested one of these cyanobacteria microbes.....................
Posted by: Mark A | Apr 23, 2008 9:59:34 PM
The authors calculation of "around 820,000 square miles, an area almost the size of the entire Midwest" should be around 1.4 million square miles.
Perhaps, the authors based their calculation only on the annual US consumption of about 140 billion gallons of gasoline. The US also consumes annually 60 billion gallons of diesel and 20 billion gallons of jet fuel. Alternatively, they may have overlooked the lower energy content of ethanol (76,000 BTU /gal.) compared to that of these petroleum-based fuels (124,000 to 135,000 BTU / gal.)
Posted by: NorthernPiker | Apr 23, 2008 10:13:03 PM
@Mark A -
while there are extremephile bacteria that can survive underneath the stomach lining (e.g. helicobacter), the hydrochloric acid + enzymes in the stomach do a remarkably good job of killing off just about everything else. In fact, if you've ever been at a beach and got even a tiny amount of salt water in your mouth, you'll have been exposed to cyanobacteria already - presumably, with no ill effects.
This GM variant actually oozes cellulose and sugars, both of which are energetically expensive to produce. I doubt such a mongrel would survive for very long in the wild - other species would feast on it and that would be that.
Posted by: Rafael Seidl | Apr 24, 2008 8:25:45 AM
They're going to have to boost production far, far more than the 17-fold increase for this to be in any way practical or economical.
Posted by: Cervus | Apr 25, 2008 12:40:27 PM
As I understand it, the closed loop designs give lots of control, but definitely run up the costs, especially as they are scaled up. The world's largest current algae producers (chlorella and spirulina, for nutritional supplements) use open-air ponds in desert areas, like California's Salton Sea.
If their productivity enhancements will work with those sorts of designs, there are other coastal subtropical deserts around the world where some careful civil engineering might allow seawater to be fed in as needed by the tides (to keep operating costs low as possible).
In fact, several spots have below-sea-level depressions (just like the Salton Sea): these include the Chott Djerd area in Algeria/ Tunisia, the Qatarra Depression in western Egypt, the Danakil Depression in Ethiopia/ Eritrea, Lake Eyre Basin in South Australia, the Dead Sea/ Jordan Valley... and I'm probably missing a couple more. Here, seawater could be gravity-fed in as needed, which again should help reduce costs. The other cost-reducers remain: they're subtropical, so heat retention problems should be reduced, they're deserts, with maximum solar exposure, and as deserts these lands are currently marginal.
One thing these operations would have over the current Mideast oilfields: they wouldn't run dry in fifty years.
Posted by: disgustedandamused | Apr 29, 2008 8:03:22 PM
