Subject: Mycobacterium tuberculosis?

From: [email-masked] (Matthew J. Gianni)
Date: 10 Apr 1995 23:10:31 -0500

Hello All,

Excuse me if this turns out to be the wrong kind of question for this 
group, but I've been studying a little bit about tuberculosis, and I'm 
not sure what is meant by the classification of mycobacterium. What are 
the distigushing features of a mycobacterium that set it apart from 
other forms of bacteria? And what, if anything, does it have in common 
with fungi?

TIA for anything that may shed some light on the subject! :)

-----------------
Matthew J. Gianni <[email-masked]>
  
Organic chemistry is the chemistry of carbon compounds.
Biochemistry is the study of carbon compounds that crawl.
		-- Mike Adams

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From: [email-masked] (DRZeiger)
Date: 11 Apr 1995 20:22:25 -0400

Mycobacteria differ from bacteria in their cell wall makeup.  Mycobacteria
have long chain mycolic acids in their cell walls.  These organisms won't
show up on a regular Gram stain.  An acid fast stain is usually needed. 
Another term used for them is acid fast bacilli.  I'm not sure if they are
related to fungi in any way, although there are some fungi that are acid
fast also.

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From: [email-masked] (Richard Winder)
Date: Wed, 12 Apr 1995 20:16:54 GMT

>related to fungi in any way, although there are some fungi that are acid
^^^^^^^^^^^^^^^^^
>fast also.

No.  Mycobacterium, Nocardia, and Corynebacterium are all gram positive 
microbes in the Actinomycete line that form mycelia to various degrees-
but they are in the prokaryotic kingdom Monera.  The Fungi constitute a 
different, eukaryotic kingdom.   -RSW

  RICHARD WINDER                    Title: Research Scientist
  Canadian Forest Service           Phone: (604) 363-0773
  Victoria, B.C.                    Internet: [email-masked]

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From: [email-masked] (Richard Winder)
Date: Thu, 13 Apr 1995 16:35:51 GMT

>other forms of bacteria? And what, if anything, does it have in common 

The genus Mycobacterium, which includes M. tuberculosis, the causal agent
of tuberculosis, is distinguished from other bacteria by its acid fastness-
cells treated with a hot phenolic solution of basic fuschin retain the dye
after subsequent treatment with an dilute acid solution.  This genus is a
member of the Actinomycetes, gram-positive bacteria which form mycelia.  In
the case of Mycobacterium, the mycelium is primitive and unstable- a
transitional form in relation to Actinomycetes with more well developed
mycelial morphology.  I would consider these mycelia to be morphologically 
analagous to fungal mycelia, rather than homologous, because we are talking 
about a prokaryotic (nucleus absent) cell versus eukaryotic (nucleii present) 
cells- different taxonomic kingdoms entirely.  In addition, most fungi have a 
cell wall made of chitin, some have cellulose or other polymers.  I think 
there is one bacterium (Sarcinaia ventriculi) with a cellulose cell wall, and 
another (Acetobacter xylinium) which excretes cellulose.  I don't know of any 
with a chitin cell wall.  Mycobacterium, along with Corynebacterium (C. 
diptheriae = diptheria) and Nocardia (N. farcinica = horse glanders) are 
distinguished from other bacteria by a unique cell wall composition.  Their 
cell wall peptidoglycans are type A (cross linked between meso-diaminopemelic
acid and D-alanine).  An arabinose/galcactose polysacharide is bonded to the 
peptidoglycan, and the wall also has a high lipid content which includes
mycolic acid (branched B-hydroxy acids, R1-CH-CH-COOH).  The arabionse
					   |  |
					   OH R2
galactose polysacharide is involved in immunilogical cross-reactivity.  If
you want to know more about *that*- you're in the wrong group!

My source for most of this info is old, so you can probably find more
up-to-date info, but here it is:

Stanier et. al. 1976.  The Microbial World.  Prentice Hall, NY. 871pp.
-RSW

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From: [email-masked] (DRZeiger)
Date: 13 Apr 1995 20:00:22 -0400

>different, eukaryotic kingdom.   -RSW

I have had a few microbiology courses and no instuctor has ever explained
that these three are related.  They were always covered separately. 
Nocardia as a fungus, Corynebacterium as bacteria and Mycobacteria on
their own.  Thank you for explaining the connection.  Now I know why the 3
look slightly similar when growing in culture (dry and crumbly).

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From: [email-masked] (Richard Winder)
Date: Tue, 18 Apr 1995 17:20:32 GMT

In article <[email-masked]>, [email-masked] (DRZeiger) 
>look slightly similar when growing in culture (dry and crumbly).

I can see why you were given the classifications that way.  Corynebacterium
doesn't really have a mycelium per se, but small groups of dividing cells 
remain attatched at angles.  Nocardia has a well-developed mycelium, while 
Mycobacterium sits somewhere in between with a rudimentary mycelium. Someone 
was just oversimplifying things a bit by ascribing all mycelial forms of life 
to the Fungi, and they ran into trouble with the intermediate form.

  Maybe we should term the study of mycelial prokaryotes "paramycology"... -RSW