A guest TQ by Stanley Maloy:
Both of the scenarios proposed by David Lipson in answer to TQ #4 make perfect sense, but they only focus on bacteria external to plants and animals (as prompted in the question). However, you could also ask what would be the impact from the demise of the normal microbial biota. Would there be a rapid effect on plant and animal life or a slow effect?
Elio has a point with the rumen flora, but I'd take a slightly different slant. All the prokaryotes are dead, because the question said so. Next all of the prokaryote-eating protists die immediately for lack of food. That takes care of all the protist-eating protists, too. While that is going on, all of the vitamin B12-dependent eukaryotes die, because prokaryotes make all of the B12 there is. We and all of the other metazons are toast within a generation. That leaves more or less the fungi and the land plants, and (maybe) some algae left over to battle it out with the elements for a while. The impact would be rapid.
Posted by: Bill Martin | January 12, 2007 at 12:07 AM
It depends if you are a human, a cow, or an aphid.
If a human, make sure you get vitamin K supplements plus some other stuff. Of course, if you include the mitochondria in "normal biota," you'd face demise in minutes.
If a cow, you'd starve to death because your main energy source are the volatile fatty acids made by the microbes in your rumen.
If you are an aphid, you'd run out of luck after a while because you can make or obtain from the plant sap you eat a number of amino acids that are normally supplied by endosymbiotic Buchnera.
Posted by: moselio schaechter | December 22, 2006 at 10:23 AM