[Bio] pH discovery that explains why my Stipticus experiments are probably failing

Roger H domitron at yahoo.com
Wed Nov 9 01:29:56 PST 2011


LOL   I just thought of an analogy of what I was doing when prepping a liquid culture medium at a pH of 3.9 for growing Stipticus (which effectively killed it).  Imagine that an alien discovers that the human stomach digests food optimally at a pH of 2.0 and that humans thrive consuming food X, but then wonders why his pet human will not eat, is bleeding at the mouth, and eventually starves to death when given food X lowered to a pH of 2.0 with hydrochloric acid.  This is not a perfect analogy, but you get the point.  


My Burning Man 2007 notes have a note in the margin that mentions that my block's initial pH was 4.9 and that I was worried about that.  I now realize that "mistake" was actually the key to my serendipitous success.

Roger



________________________________
From: miloh <froggytoad at gmail.com>
To: Roger H <domitron at yahoo.com>
Cc: Rikke Rasmussen <rikke.c.rasmussen at gmail.com>; "bio at lists.noisebridge.net" <bio at lists.noisebridge.net>; "tastebridge at lists.noisebridge.net" <tastebridge at lists.noisebridge.net>; Matthew Downs <downs.matt at gmail.com>
Sent: Tuesday, November 8, 2011 10:36 PM
Subject: Re: [Bio] pH discovery that explains why my Stipticus experiments are probably failing


Is it me, or is 3 a hella low ph?
Good notekeeping!
On Nov 8, 2011 8:36 PM, "Roger H" <domitron at yahoo.com> wrote:

I believe I have discovered my mistake in growing the Stipticus. The starting pH of a wood-decomposing substrate should be higher than the growth pH.  White-rot wood-rotting fungi such as Stipticus decrease pH through the release of oxalic acid.  The starting pH in the research paper I found online* suggests that the fungi is well accustomed to a starting wood pH of around 5.1, which a white-rot fungus takes to 3.9 (ideal is 3.5-3.8 in this species).  Thus by me starting the pH of the liquid culture at 3.8, the fungus probably cannot grow to release oxalic acid to lower the pH as it does in nature.  And my Burning Man 2007 bags DID start at a pH of about 5, actually by mistake according to my notes!  So, I think I have solved the problem of why nothing is working when I lower the pH to the optimal growth pH.  I will start a new liquid culture at a pH of 5.0 and bags accordingly and allow the fungus to lower the pH to the ideal growth level as it
 does in nature.
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>Roger
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>* See: http://les.bf.uni-lj.si/fileadmin/datoteke_asistentov/mhumar/clanki/2001_pHafterdecay_holz_als_roh.pdf
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>PSS - A 4% dextrose/light malt liquid culture as I was using is around 5.3 pH without anything added.  Under these conditions the mycelium was growing very well, which correlates with my hunch that I should not be dropping the pH to the optimal growth-stage pH but rather let the mycelium handle the drop.
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