clean clones (Paul Stewart)

Warren Rekow pub907 at IDPTV.IDBSU.EDU
Sun Mar 26 22:57:15 EST 1995

Paul, I have done several isolations from store-bought mushrooms and have
not had any particular problems with doing so.  Some comments per your

> I have tried wiping the outside of the mushrooms with ethanol (70%), but 
> still get bacteria in my cultures. I keep cultures at 25-26 C. I have 
> done lots of plant tissue culture and so tried ...

It may not be a good idea to try disinfecting the mushrooms in the same way
that one would do with plant tissue cultures.  The mushrooms do not have a
waxy cuticle, so the disinfectants may be penetrating into the fungal
tissue with resultant loss of viability.  I have observed fruiting bodies
which have dried out a bit will readily absorb water.

> Is contamination from cloned storebought a problem others have 
> encountered and solved? (frustration mounts with each passing week!)

I buy the freshest mushrooms available and then culture them ASAP by
spliting the cap & stipe in half by manual tearing (no interior contact)
and then cutting out and plating small tissue samples from the upper stipe
center and cap center.  Same as for most wild isolations.  HEPA filter,
flame-sterilized scalpels, autoclaved agar, and careful clean-room tecnique
are used.  From your message I cannot tell what the most probable sources
of contamination are.  Stamets' 2 books are excellent, as are his classes.

> BTW...while I'm going on and on...I posted a question recently regarding 
> using a horizontal oil drum with a hatch cut in the side as a rolling 
> spawn generator. Any comments yet on this?

Sterile conditions are essential for spawm making.  How will contaminants
be excluded from the spawn using this method?  Why is this better than
using bags?

Best wishes
Warren Rekow (pub907 at
HC 79, Box 104, Melba  ID  83641
Phone or fax: 208-896-4908

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