H2O2 in Agar Medium?

RushWayne rushwayne at aol.com
Fri Feb 7 17:07:47 EST 1997


Dear Keith,
Joe Harrington forwarded to me your inquiry about using
hydrogen peroxide in mushroom culture.  As he states,
it is definitely possible to grow mushrooms with
hydrogen peroxide.  It can be added to agar medium, to
spawn, and to certain selected fruiting substrates.

Peroxide is capable of killing single celled organisms
such as yeast and bacteria, and spores of molds and fungi,
but established multicellular organisms are resistant to
it.  This is because all living organisms contain peroxide-
decomposing enzymes (catalases and peroxidases), and
actively growing multicellular organisms, such 
as mushroom mycelium, (but also molds) contain enough
of these enzymes to defend themselves against added
peroxide and continue to grow, whereas single- 
celled organisms and newly germinating spores are overwhelmed by the added
peroxide.  

Peroxide is not chemically stable above about 60 degrees
Centigrade, so it has to be added when the culture medium
is cool.  This is somewhat of an inconvenience, but not a
major one.

Because growing mycelium is full of peroxide
decomposing enzymes, if the peroxide concentration 
is kept to the lowest effective level, the peroxide 
has little opportunity to have any mutagenic effects on 
the mycelium.  I have been growing mushrooms on 
peroxide for three years and I have not seen anything 
that looked like a mutation.
I do not add peroxide to storage slants, however, as the
inactive cells in a slant would be less able to defend 
themselves against the external peroxide, and deleterious
changes might result.

Some have also expressed concern that peroxide might
react with the substrate and leave mutagenic residues
in the mushrooms.  Since peroxide is chemically stable
in mushroom substrate when it is prepared properly
(otherwise it would not stay around long enough to prevent 
contamination), I think this is unlikely.  The 
concentrations of peroxide are also quite low.  

I am also a home-based grower working with a kitchen
laboratory.  I developed the peroxide method exactly
because I didn't want to build all kinds of air filtration
equipment and clean rooms, etc.

Although peroxide can be added to fruiting substrates,
there are two requirements:  the substrate cannot 
contain any peroxide-decomposing enzymes, and it cannot
contain live organisms.   Compost fails on both these
counts, unless it is extensively cooked (not an appealing
prospect!)  Wood pellet fuel is the best substrate I
have found.  Clean cardboard might also work.  Pelletized
paper fiber (Crown Animal Bedding, Good Mews Cat Litter)
can also be used.  Peroxide is not stable in straw, but
straw is relatively easy to pasteurize by other means.
Of course, some mushrooms will grow on compost 
without pasteurizing it, so you could go that route too.

I have worked for three years to create a set of reliable
protocols for using peroxide in mushroom growing, and
my peroxide manual contains the results of that work.
The manual currently costs $19.95 plus $2.05 for first 
class mail shipping in the U.S. and packaging.  E-mail
me for ordering information if interested.
--Rush Wayne



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