Subject: How to screen acid producing fungi?

From: [email-masked] (r3603201)
Date: 21 Mar 1995 04:14:56 -0800

I have been using PDA + calcium carbonate for the screening of acid 
producing fungi, but the outcome was not satisfied. Does anyone have any 
effective method for the screening of acid producing fungi? Where could 
be the possible habitat of the microorganisms?

---

From: [email-masked] (Jessie Micales)
Date: Tue, 21 Mar 1995 08:03:08

>be the possible habitat of the microorganisms? 

Many brown-rot wood decay fungi produce "tons" of oxalic acid driving the pH 
of decaying wood down below 2.0 in some cases.

There are pH indicator dyes that detect low pH that can be incorporated into 
media (assuming they aren't too fungitoxic!).   See: Green, F. III, Larsen, 
M.J., Winandy, J.E., and Highley, T.L.  1991.  Role of oxalic acid in 
incipient brown-rot decay.  Material und Organismen 26:191-213.  If you
can't find this journal, E-mail me your address and I will send you a 
reprint.

So why are you looking for acid-producing fungi?

Jessie Micales ([email-masked])

---

From: [email-masked] (mspear)
Date: 1 Apr 1995 14:20:28 -0500

> be the possible habitat of the microorganisms? 

How about using a dye in the medium like bromthmol blue or creasol
green.  These would definately stop some fungi from growing but those
that do might change the color of the medium.  Some pH sensative dye
might work so that the spots that turn color could point out the acid
producers.

    ---- Mark