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Researchers Identify Four Cellulase Genes in Termite Digestive System

27 February 2007

The ability of termites to eat wood and break the cellulose down into glucose quickly and efficiently have made studying the insects a point of focus for a number of scientists, including Nobel laureate Steven Chu, now Director of the Lawrence Berkeley Labs, who would like to apply that capability to the large-scale generation of ethanol from cellulosic materials.

Researchers at the University of Florida and Purdue University have identified four cellulase genes—one in the Eastern Subterranean Termite (Reticulitermes flavipes) and three in microscopic symbionts that live inside the termite digestive system. Their study is published in the journal Gene.

This is a significant step forward, especially because we looked at the dominant termite species in the US. But we’re confident we haven’t identified all the genes involved in producing these enzymes.

—Michael Scharf, co-author

There may be hundreds of cellulose-digesting enzymes produced by the termites and their symbionts, according to Scharf.

The interaction of multiple genes makes cellulose digestion an efficient process in termites, but scientists want to pin down enzyme combinations that will digest cellulose affordably. UF researchers have applied for funding to support a massive effort to identify all cellulose-digesting genes in the eastern subterranean termite and its common symbionts.

Diversa, Caltech, Instituto Nacional de Biodiversidad and the Joint Genome Institute are also working on identifying cellulase enzymes in termite guts.

One potential approach to applying the research would be transferring specific cellulase-expressing genes into bacteria, optimizing them and then culturing the leading bacteria to produce large quantities of enzymes to make ethanol from wood scraps and other fibrous materials.

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February 27, 2007 in Biotech, Cellulosic ethanol | Permalink | Comments (14) | TrackBack (0)

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Comments

How will we keep bacterial termites from eating the wood in our houses?

Orkin.

Little itty bitty orkin extermimators.

A little kerosene and a match.

I was watching a show on the Discovery Channel last night, Dirty Jobs with Mike Rowe, and thought: "termites readily eat the cellulose in wood, why aren't we using them for cellulosic ethanol production?"

I guess some other people have been thinking the same thing....

'I was watching a show on the Discovery Channel last night, Dirty Jobs with Mike Rowe, and thought: "termites readily eat the cellulose in wood, why aren't we using them for cellulosic ethanol production?"'

John,
Yes, termites eat the cellulose in wood. But the glucose they produce from breaking down the cellulose is used by the termites not excreted. So, that doesn't help us. But, if we take the genes out of the termites for the enzymes to breakdown cellulose and put them into a bacteria, we can overproduce those enzymes. The enzymes can be purified from the bacteria. The purified enzyme can be put into tank that contains cellulosic material and water. Once the enzymes have did their thing, we can move the glucose-rich liquid into another tank. Then we add our E. coli to the liquid to ferment the glucose to make ethanol.
One potentially scary thought is that if they sucessfully clone the correct genes into a bacteria, will they be able to contain it? If it gets into the wild and over time changes, it could become airborn and get on everything. Say goodbye to your house, your trees, and the forests. Yes, it's a little melodramatic, but one has to think of the possibility.

Actually you take the cellulase genes out of the termites, evolve them so that the cellulase proteins act only at high temperatures, and insert these genes into the switchgrass that you're growing. The plant then manufactures both the cellulose that you want to convert and the cellulase enzymes. You grind up the switchgrass in a slurry and heat it and voila the cellulases turn on, converting the switchgrass to syrup that is then a feed for yeast.

After doing a little research into this arena, I found that this may not be a feasible as one might think. The idea is good, but the feasiblity isn't. There was an article is Science magazine talking about this very subject. Nature has made it so that there is a complex system to breakdown cellulose and the system runs at a constant slow rate. Also, there is multiple enzymes needed to breakdown cellulose. One enzyme moves in and starts breaking down some of the cellulose. It gets to a point where it has to stop. It gets off and another enzyme gets on to continue the breakdown. Then this enzyme gets off and the first enzyme comes back to do some more work. The point is is that there are some spacial constraints to the system when you try to breakdown cellulose. That's why it's a slow process. You also can't add each enzyme one at a time for the system to work. To heat up the material to speed up the reactions would be adding extra energy and cost to the manufacturing side. We don't want to add any more energy into the system than we have to.
Even if we found enough of the enzymes to breakdown cellulose, it may not be a very efficient process.

Don't worry about the number of enzymes, you make them all for "free" in the switchgrass (and this hadn't been done, really, as of 2 years ago). Sure, the enzymes work in tandem, they get off the cellulose strand when they need to, and find a different one to work on while a different enzymes comes in on that previous strand. The great thing is that the amount of enzyme you need becomes irrelevant; the switchgrass makes them, you don't even have to purify, store, ship, etc. They are there, in excess, waiting for you to heat them up to activate them. And by heating, I'm talking 40-50C, just above what they would experience in the field.

I am ph.D scholar in fisheries science, I would like to isolate the gene which is responsible for cellulase enzyme production in termites, and transferring this gene in to Lactobacillus bacteria to produce cellulase enzyme. So that the newly developed strain can be used as a feed probiotics, will be helpful in synthesizing of cellulase enzyme to digest carbohydrates in fish feed.

Note: Most of the fishes do not synthesize cellulase enzyme so that it is not capable to utilize the carbohydrate as a energy source from the feed.

Whether it can be possible to do?

I have been working on termite probiotics for the use as a stop-gap for methanol/ethanol in reduction of fiberous material in distilling of alcohol based fuel production for years. I've developed a good (green) process to make an affordable,internal combustion (heptane +) ethanol fuel. Seems the phd's are catching up with me for a change. Interested? robart54@hotmail.com

If we are going to put the gene into the Lactobacilli for fish and feed them cellulose, why don't we just put the probiotics in our own gut and we could just eat wood. Then what would we do for fiber in our diets? And do fish need fiber in their diet? And can this gene be transferred to other bacteria present in the gut, with unimagined consequences?

I am vet.it is possible in animal.after transfer of gene into lactobacilli.we can use this as probiotic and then feed paper waste wood.But i don't know animal eat these or not because tastebud is problem

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