Subject: Re: Are Deuteromycetes Universally Amylolytic?

From: [email-masked]
Date: 23 Sep 1996 03:41:20 -0700

I am refering to clearing zones around the fungal colony while the rest of
the water based agar (plus mineral salts minus CHO source) are stained  with
brownish-yellowish color of iodine stain. I think this is the color  dextrin,
or partialy degraded  amylose impart with iodine  solution.Try it with any
deuteromycetes (stick to the old meaning of deuteromycetes because somebody
is asserting that deuteros are ascomycetes..). that's why I am proposing that
deuteromycetes are universally amylolytic whether it may degrade amylose or
probably its swollen  counterpart or its molecular intermediate form.

In case the deuteros produce amyloid around its vicinity then might as well
 stain around it but that is not the case with my experiement..it is  a
clearing zone that develops.

ITS
Research Consultant

---

From: [email-masked] (Steve Carpenter - Cascade Research Assoc.)
Date: 24 Sep 1996 13:19:15 GMT

You are going to have to test an overwhelming number of organisms to prove
any "universal" hypothesis about the Deuteromycetes.  

The Deuteromycetes are, basically, "the rest of the fungi" i.e. the
asexual fungi.  Their lineages trace to the Basidiomycetes, Ascomycetes,
Zygomycetes, and so forth.  

As a group, the Deuteromycetes have no high degree of relationship
phylogenetically, which implies no high degree of relationship
biochemically or physiologically.  Within any given "genus" of
Deuteromycetes, there IS, of course, a greater degree of relationship. 

I'm not trying to say you are wrong in trying this, but a claim to 
anything universal about the Deuteromycetes is a tough nut to crack and 
would require a phenomenal amount of testing across all known taxa.

-Steven E. Carpenter
 Cascade Research Associates
   & Abbey Lane Laboratory
 [email-masked]

[email-masked] wrote:
: I am refering to clearing zones around the fungal colony while the rest of
: the water based agar (plus mineral salts minus CHO source) are stained  with
: brownish-yellowish color of iodine stain. I think this is the color  dextrin,
: or partialy degraded  amylose impart with iodine  solution.Try it with any
: deuteromycetes (stick to the old meaning of deuteromycetes because somebody
: is asserting that deuteros are ascomycetes..). that's why I am proposing that
: deuteromycetes are universally amylolytic whether it may degrade amylose or
: probably its swollen  counterpart or its molecular intermediate form.

: In case the deuteros produce amyloid around its vicinity then might as well
:  stain around it but that is not the case with my experiement..it is  a
: clearing zone that develops.

: ITS
: Research Consultant

---

From: [email-masked] (Eric Robb Siegel)
Date: 25 Sep 1996 18:56:19 -0700

Is your iodine solution Melzer's reagent, or some other iodine solution?
Using Melzer's reagent, the dextrinoid reaction is pink while the amyloid 
reaction is blue, according to Alexopoulos, Mims, & Blackwell.  I think 
the Melzer's reagent has chloral hydrate in it, but that may just carry 
the iodine across cell membranes to intracellular starch stores.  Its 
presence or absence shouldn't affect the colors you get using iodine 
on an extracellular CHO deposit.(...but I could be wrong; I don't know.)  
About eight or nine years ago, I used iodine *vapor* to stain 
amylopectin-agar plates colonized by starch-debranching *Bacillus* spp., 
and got results consistent with the above description of the Melzer's 
reaction with different kinds of starch.

Brownish-yellow iodine color in your agar sounds like uncomplexed iodine.
The only CHO present, you said, is the agar itself, plus whatever impurities 
come in the agar.  If you substitute 1% electrophoresis-grade agarose for 
your 1.5% Bacto agar (or Oxo agar, or whose-ever agar), do you get the same 
color at the same intensity?

Is the clearing zone around your colony immediately apparent when you 
flood the plate with iodine stain? or does the clearing of the color take 
a while to appear?  What color does the colony itself stain?  How wide is 
the clearing zone, and is the loss of color in the clearing zone total 
or partial?  If partial, is the amount of clearing "mostly cleared" or 
somewhat less than that?  

Can you flood the plate with anything else, such as a pH-sensitive dye, 
perhaps, and look for zones that coincide with your iodine clearing?

Finally, what happens when you grow your colony on agar that *does* have 
starch in it, and stain *that* with iodine?  (I used to use Kingsford 
corn starch from the supermarket, and Lintner Soluble Starch from---was 
it Bacto?  There's also lots of starch in Potato Dextrose Agar, 
particularly the home-made variety.)

I must admit I am puzzled over why you would get clearing of the iodine 
stain by a fungal colony on water agar.  But at this point, you have no 
evidence for amylolytic activity from your fungi, because you have no 
starch in your medium.  Do you suppose that what you are seeing is 
agarolytic activity rather than amylolytic activity?  

Eric