Bacteriology Questions

Joel Gagliardi jg121 at UMAIL.UMD.EDU
Tue Apr 28 18:46:52 EST 1998


> Are there any other reasons why bacteria would produce antibiotics?

Take penicillin as an example.  Penicillin is produced naturally by the
fungal genus Penicillium.  Penicillin is active against peptidoglycan
synthesis enzymes - peptidoglycan is unique to bacterial cell walls and
without a cell wall, the bacterial cell will not survive.  Penicillin was
discovered on a petri dish by Alexander Fleming who was working with a
bacterial pathogen ( the exact genus and species escapes me).  He noticed a
zone around the Penicillium contaminating the plate where no bacteria would
grow.  It took approximately 10 years to develop this into antibiotic
therapy for treating bacterial infections.  If you plate out dilutions of
fresh soil onto a general growth medium, and also the same medium with
either cyclohexamide or streptomycin to inhibit fungi and bacteria
respectively, you may see a crude example of the interactions that take
place in soil by observing the zones of inhibition.  (This is one reason
why soil plate counts are notoriously inaccurate).

I cannot currently think of another good reason for the production of
antibiotics other than to compete with other organisms.

> Are the reasons for producing toxins the same?  

The definition of antibiotic is essentially, 'kills living things'. 
Traditionally, antibiotic means active against bacteria, while toxin means
active against higher organisms.  I would say the terms are synonymous. 
You have to review each toxin to determine why the organism evolved the
ability to produce this and why it maintains this ability.

Are there any disadvantages?

Plenty.  For one, it takes cell metabolic energy to produce antibiotics, so
there must be an advantage gained in survival to maintain this trait.


Joel
> 
> Andy Rossmeissl
> 
> In article <199804281726.NAA05203 at umailsrv0.umd.edu>,
>   jg121 at UMAIL.UMD.EDU ("Joel Gagliardi") wrote:
> >
> > The bacteria producing the most antibiotics are the actinomycetes and
> > strpetomycetes - both common soil organisms.  The most common reasoning
is
> > that they use antibiotics when competing with other organisms for
habitat,
> > and maybe food.  Fluorescent pseudomonads produce classes of
antibiotics as
> > well that are suppressive to fungi.  Fungi also produce many
antibiotics
> > that suppress bacteria and other fungi.
> >
> > In order for the producing organism to survive, it must have an
antibiotic
> > resistance mechanism such as a detoxifying enzyme, or be naturally
immune
> > to the innate antibiotic.  The prevalence of the resistance mechanisms
with
> > the antibiotic producing traits somewhat explains the spread of
antibiotic
> > resistance to animal pathogens.
> >
> > ----------
> > > From: Andy Rossmeissl <thelight at GEOCITIES.COM>
> > > To: microbio at net.bio.net
> > > Subject: Bacteriology Questions
> > > Date: Monday, April 27, 1998 7:15 PM
> > >
> > > Why do bacteria produce antibiotics?  Isn't that kind of
> > counterproductive
> > > -- don't antibiotics kill bacteria?  I'm aware that they probably do
this
> > > to cut down on competition but won't their own antibiotic envetually
kill
> > > the bacteria that made it?
> > >
> > > Thank You,
> > > Andy Rossmeissl
> > > thelight at geocities.com
> > >
> > >
> > >       /-----------------------------------------------------/
> > >      / Andy Rossmeissl     //     thelight at geocities.com   /
> > >     /-----------------------------------------------------/
> > >    / Into the light...   //  TeamOS/2  //  Madison, WI   /
> > >   /-----------------------------------------------------/
> > >  /ICQ UIN: 1200747 //Page me:wwp.mirabilis.com/1200747 /
> > > /_____________________________________________________/
> >
> 
> 
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