GROWING GOURMET - Anto2ni.it

GROWING GOURMET MUSHROOMS ON ENRICHED SAWDUST 177
the incubation room warmer than recommended
is likely to cause the internal
incubation temperatures to rise to dangerous
levels. Carbon dioxide levels within the laboratory
should never exceed 1000 ppm, although
20,000-40,000 ppm of CO2 is typical within the
bags as they incubate. This steep slope of high
CO2 within the bag to the low CO2 in the atmosphere
of the laboratory is helpful in controlling
the evolution of metabolic processes. Should the
gradient be less severe, CO2 levels can easily exceed
50,000 ppm within the incubating bags. At
this and higher levels, mycelial growth lessens
and contaminants are encouraged. To compensate,
the laboratory air handling system must be
adjusted for the proper mixing of fresh vs. recirculated
air. (See Appendix II Designing a
Laboratory)
Three days after inoculation the mycelium
becomes clearly visible, often appearing as
fuzzy spots of growth. Second shaking, although
essential for insuring full colonization
of grain spawn, is not usually advisable in the
incubation of supplemented sawdust. If complete
sterilization has not been achieved,
second shaking can result in a contamination
bloom. If one is certain that sterilization has
been achieved, second shaking helps colonization,
especially around Days 4-5.
Each species uniquely colonizes supplemented
sawdust. Oyster mycelium is
notoriously fast, as is Morel mycelium. "Good
growth" can be generally described as fans of
mycelium rapidly radiating outwards from the
points of inoculation. Growth is noticeable on
a daily, and in some cases, on an hourly basis.
When the mycelium loses it finger-like outer
edges, forming circular dials, or distinct zones
of demarcation, this is often a sign that contaminants
have been encountered, although
they may not yet be visible. The behavior of the
mycelium constantly gives the spawn manager
clues about the potential success of each run.
Large runs of supplemented sawdust are
more likely to host minute pockets of
unsterilized substrate than smaller ones.
Should colonization be inhibited, encouraged by
any number of factors— poor strain vigor, a dilute
inoculation rate, elevated internal thermal or carbon
dioxide levels—contaminants are to be
expected. This race between the mycelium and legions
of competitors isa central theme operating
throughout every stage of the cultivation process.
Achieving Full Colonization
on Supplemented Sawdust
Prior to the mycelium densely colonizing
the blocks with a thick and tenacious mycelial
mat, the supplemented sawdust appears to be
grown through with a fine, but not fully articulated,
mycelial network. With most species, the
once brown sawdust mixture takes on a grayish
white appearance. With Shiitake mycelium,
this is usually between Days 3-7. During this
state, the mycelium has yet to reach its peak
penetration through the substrate. Although the
substrate has been captured as a geological
niche, the mycelial network continues to grow
furiously, exponentially increasing in its micro-netting
capacity. The bags feel warm to the
touch and carbon dioxide evolution peaks.
Within hours, a sudden transformation occurs:
The once-gray appearance of the bags
flush to snow-white. The fully articulated, thick
mycelial network achieves a remarkable tenacity,
holding fast onto the substrate. Now when each
block is grasped, the substrate holds together
without falling apart, feeling solid to the touch.
The blocks can be further incubated until
needed, within certain time restraints. (Refer to
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