Wednesday, April 13, 2011

Bacteria in the guts are good for you?


Termites have roamed the earth since the time of the dinosaur yet most species have not yet developed a way to digest cellulose on their own [1]. Millions of years ago, termites learned that a bacterium in their gut could help them break down the cellulose and plant fibers that they eat [2]. Since then termites and Trichonympha have lived in a symbiotic relationship with one another. Most ever species of termites share

a relationship with the bacterium Trichonmympha and because termites are found worldwide, and mostly in tropical areas, so is their bacterium [3].

The life cycle of a termite is depended on two things: the species and the environment. Some species live longer than others and some environments support termite life better than others. Warmer climates allow termites to live a longer life [4]. A queen termite in some species can live for a decade or more while a worker or solider termite has a life span of one to five years. A termite goes through three stages of development. Eggs hatch to reveal nymphs from there two different types of termites develop: the worker

termite and the solider termite. Both types continue to molt and form into the adult termite. Due to termites having incomplete metamorphosis, both worker and solider termites grow wings. This stage with wings is called the alates stage. The termites continue to grow and they shed their wings. From there a king and a queen termite mate and the female lays more eggs to continue the cycle [5].

Termite nymphs are not born with the bacterium Trichonympha but rather they must be infected with it from one of the older termites. Every time a termite molts it must infected again in order the termite to survive [6].

Description of Relationship:

Most species of termites and the bacterium Trichonympha, from the genus parabasalian, have a mutualistic relationship, meaning that each benefits from the other. The termites are placed in a category of eusocial insect meaning that they raise their young as a group [7]. As a nymph, these termites are white in color and are thus referred to as “white ant” [2]. The colonies of termites consist of two different forms of termites. The worker termite is blind, wingless and sterile. It is unpigmented, soft, and works in dark moist areas. Worker termites are needed to build nests, get good, and feed the solider termites. The solider termites are every bit the same in appearance as worker termites except solider termites have a hard cuticles rather than soft ones and they have a brown head rather than a white one. Solider termites also have large mandibles that allow them to defend the colony against intruders [8]. King and queen termites have wings that are twice the size of their bodies and their main job in the colony is to reproduce [9].

Trichonympha inside the gut of the termite helps the termite digest cellulose and plant fibers that the termite could not digest on its own. This adaptation has allowed termites to survive for millions of years while allowing the bacterium to continue developing. The bacterium inside the termite engulfs the eaten wood or plant substances and uses a bacterium of its own to break it down.

Cost/Benefit Analysis:


  • Cost: must be infected with bacterium in order to survive
  • Benefit: bacterium helps termite get its food digested


  • Cost: they have to live inside termites otherwise they cannot make cellulose for their own self
  • Benefit: termites provide food and shelter [10].













  1. Did you read anything about how/why this relationship does not develop into a parasitic one- the bacteria parasitizing the termite? Why doesn't the bacteria run rampant in the stomach, taking all the nutrients from the termite, for example? Or what methods do the termites employ to keep the bacteria "at bay"?

  2. We’ve read a lot this semester about parasites that influence a host’s behavior. Does this bacterium (although it’s not a true parasite) have some system in place for ensuring that as many termites as possible are infected? Do the termites have their own system in place to routinely infect/re-infect members of the nest who do not carry this bacterium, or do they just pick it up from their peers haphazardly?

  3. Josh: I didn't know where to mention this in my blog but I did read that the bacterium also has a bacteria on it because Trichonympha can not produce its own cellulose and so this other bacteria helps Trichonympha produce it. I'm not a 100% sure why the bacteria don't run rampant but I believe its because they have a benefit by staying.

    Ellen: Because this is a mutualistic relationship both the termites and the bacteria want to get the benefit of each other. In saying this I mean that the bacteria can not live alone, without the termites they would not be able to survive because they would not have a proper shelter. The termites on the other hand will starve without the bacteria and so they absolutely need the bacteria. In my research all I found was that the bacteria is highly "contagious" and so spreading it from one termite to another is very easy, however I am not sure exactly how they they go about spreading.

  4. When the termites die, what happens to the bacteria? Can they live without a living host or do they perish with the host?

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  6. I wonder why over the years the mutualistic relationship between the bacteria and the termites has not evolved into an endosymbiotic one. If the termites have been around since the dawn of creation then why have they not become genetically intertwined with its host as mitochondria did? These are merely conceptual questions; I doubt there's a solid answer because its only conjecture. Are the bacteria found anywhere else? I know you said that they cannot exist without their host but how does the initial infection occur, do the hosts ingest the parasite or does the bacteria inject itself?

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