Re: Cellulose digestion

dkomo <dkomo871@xxxxxxxxxxx> wrote in
news:DuWdnb8DUN4GEnnYnZ2dnUVZ_h2pnZ2d@xxxxxxxxxxx:

I'm doing some ruminating about extragenetic hereditary mechanisms and
I
need some quick questions answered about cellulose digestion and
animals
that use it. I don't have time to google for the answers.

The two animals I'm using as examples right now are cattle and
termites,
both of which use microcrobes to digest the celluose they ingest.

Questions:

1. Do all animals (mainly insects and mammals) that subsist on
cellulose
need microbes to digest it? If so, why? Why can't the animal
manufacture all the enzymes needed to digest cellulose?

2. What fraction of herbivores are strictly cellulose eaters?

3. When humans eat leafy vegetables like lettuce spinach, why are they
able to digest it?

3. In the case of newly born cattle and newly hatched termites, how do
the cellulose digesting microbes get into the animals' guts?

4. Are the microbes considered to be symbionts or parasites?

This is probably too late to help, but:

The "primitive" termites need microbes. The more derived termites have
evolved many of the enzymes required.

Termites lose their symbiotic microbes during molting and have to
reacquire them by eating the feces of other termites.

As to why utilize symbionts, as others have noted it is probably because
that was the easy way. Digesting cellulosic materials such as wood
(actually a combination of cellulose, hemicellulose, and lignin -
basically a fiber reinforced plastic) requires two processes: breaking
up the frp, and then hydrolyzing the cellulose. Ruminants and termites
are good at the first, but found it convenient to use symbionts for the
second. The microbes have great difficulty with the first, but could
readily supply the second, so the symbiosis could easily become a
mutualism.

Yours,

Bill Morse

.

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