Tue Mar 7 10:00:10 EST 1995

John Cherwonogrodzky urges members of this discussion group to engage in 
discussion of fundamental principles every now and then, and that's a good 
idea.  He poses as a suitable subject the question of what is the "true" 
function of antibiotics, and raises the possibility that it "is primarily to 
shut down or inhibit biochemical pathways in the producer so that it can mature 
into a different form. It just so happens that this inhibition works on other 
life-forms. If so, even in relatively simple life-forms, antibiotics are being 
produced to regulate or change pathways."  He notes that what the antibiotic 
producers have most in common is a "complicated life style".

In reply, I would suggest first that while the bacterial antibiotic producers 
may indeed have more "complicated" life styles (e.g., spores) than do many 
other bacteria, it isn't a very tight correlation (not all spore-formers 
produce known antibiotics) -- and besides, the same doesn't hold true of the 
molds, which are very simple compared to their teleomorphic (sexually 
reproducing) cousins.  Antibiotic secretion seems more closely tied to 
ecological role than to morphological complexity.

Second, while some self-regulatory function is always a theoretical possibility 
until disproven (ah, to disprove the negative), the fact still remains that in 
the case of penicillin, at least, it would be a surprise indeed if its 
marvelously specific activity against murein synthesis (strictly prokaryotic) 
should turn out to be only an accidental side-effect of some entirely different 
and as yet undiscovered role in Penicillium's own development.  Pending at 
least *some* evidence of autoregulatory function, this aspect of the hypothesis 
seems unpersuasive.

Cherwonogrodzky is right to keep us questioning our paradigms, but until 
someone genetically blocks antibiotic production in a normally producing strain 
and shows a correlated block in some stage of development, we should continue 
to think of antibiotics as being primarily, if not solely, weapons of 
interspecific competition.

Terry W. Hill
Dept. of Biology
Rhodes College
Memphis, TN  38112

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