[Bio] pH discovery that explains why my Stipticus experiments are probably failing
domitron at yahoo.com
Tue Nov 8 20:36:14 PST 2011
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.
* See: http://les.bf.uni-lj.si/fileadmin/datoteke_asistentov/mhumar/clanki/2001_pHafterdecay_holz_als_roh.pdf
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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