Termite Digestion

 

            Starch and cellulose are both polymers of glucose produced by plants and both are insoluble in water.  Plants create cellulose to form their structure and once glucose molecules have been strung together by the plants to make fibers (wood is the most salient example). it is unavailable to the plants for any future chemical manipulation.  Plants store starch in their roots, seeds and deep layers of the bark as the source of energy and material for growth spurts as when seeds germinate or perennial plants put on their annual spring growth spurt.  Glucose is formed in green plants from carbon dioxide in the air and water from the soil.  This chemical reaction does not proceed spontaneously because it requires a source of energy.  In nature, this energy is supplied by the light of the sun with an assist from chlorophyll.  The glucose travels dissolved in sap to the root, bark or seed for storage where it is converted to starch for future use as structure and energy to create the new structures.

 

            When animals need energy, they eat plants (or each other).  Only a few kinds of animals can obtain energy from cellulose and only with assistance of bacteria in their digestive tracts.  Ruminants do it with their multiple stomachs containing the necessary bacteria and their cud chewing to increase the contact time of the cellulose and the bacteria because even the bacteria can digest cellulose only slowly.  Horses, elephants and rabbits do it less efficiently by harboring the necessary bacteria in the cecum, the upper part of their large intestines.  Incidentally, if you deliver a calf by caesarian section and keep it in a sterile environment, it cannot digest cellulose until you release it into our dirty, bacteria-containing world.  The hoatzin, a beautiful auburn colored bird of South America as big as a chicken, eats leaves and digests the cellulose in its crop (gizzard).  The bird has halitosis and cannot fly very far because the digestion of cellulose is so slow that it quickly runs out of energy, but it does have a handsome crest.

 

            Termites also digest cellulose with the assistance of bacteria.  When I was in school, it was not known how they managed it in their tiny bodies.  It turns out that they also require a variety of swimming one-celled animals with a hairy surface to harbor the bacteria.  These swimming one-celled animals are called paramecia (just one of them, a paramecium).  By swimming upstream in the termite’s intestine with their resident bacteria, they help the bacteria avoid being expelled and increase the contact time with the cellulose to be digested.

 

            At a session of the AAAS (American Association for the Advancement of Science) February 15, 2003, on sustainable development an expert from Brazil on ethanol production in industrial quantities described how they had succeeded in switching a significant fraction of their automobile fleet to 100% ethanol fuel.  Since discovering petroleum off the northeast coast of Brazil a few years ago, this percentage has slipped some because of the inefficiency of producing vehicle fuel from a high value crop like sugar cane.  When we make increasing quantities of ethanol from corn (for political reasons?), we have stubbed our toes on the same problem of expending fossil fuel energy in the manufacture of ethanol in an amount approximately equal to that provided by the ethanol.

 

            Cellulose has been converted to glucose using heat in an acid medium, but it is not cost effective so far at least partly because it has to be done in batches neutralizing the acid before introducing yeast for the fermentation of glucose to ethanol.  In general, continuous processes are more economical than batch processes on an industrial scale.

            A suggested remedy:  Create an industrial sized termite intestine complete with paramecia and cellulose digesting bacteria, put the chopped or powdered crop waste (cellulose) in the front and get glucose solution out, ready for the same fermentation process now done in ethanol factories using sugar cane or corn.

 

John A. Frantz, MD

February 20, 2003

 

Addendum:……Getting biomass ethanol from the laboratory to the highway has been slow.  BC International of Dedham, Massachusetts, which plans to build a plant in Louisiana to convert sugar cane waste into fuel, is having a hard time getting $90 million to build the refinery.  “It’s a combination of the economy and the fact that it’s the first of its kind,” says Vice President John Doyle.  “Bankers and investors love to say, “Where is one of those running?’”

U. S. news and World Report, 2-17-03, bottom of page 38

Microbiol Biotechnol (2003) 61: 1-9 describes termites in great detail.  Most of the 20 or so organisms that help termites to digest cellulose have not been cultured, but some have been identified by PCR (polymerase chain reaction), and presumably some are awaiting discovery.  The bottom line: the products of termite digestion of cellulose include acetate, methane, hydrogen, and little or no glucose.  So a giant ruminant stomach substitute looks more promising than trying to imitate termites for alcohol production.  However, these mind experiments have been diverting. I still like the idea of using waste instead of a food crop. In the future, when I stray from medicine and health, I will pause a little longer for more research before going public.

 

How are washing machines and riding lawn mowers alike?

 

Our daughter was riding with us to St. Louis to our grandson’s (her nephew’s) wedding.  The above question occurred to me as I observed her watching a man on his riding lawn mower mowing the 5-acre (approximately) lawn of his trophy house.

 

When we get washing machines, most of us don’t get the full advantage of the labor saving device because we wash more stuff more often using up much of the time and effort we might have saved.  Riding lawn mowers permit the same “wheel spinning” compulsion.

 

And when we get good roads and automobiles, many of us spend two hours per day commuting—ample time to put in quite a large garden resulting in great health improvement for the entire family.

 

John A. Frantz, M.D.

June 19, 2003