The prototypic Oyster mushroom, Pleurotus ostreatus has long
been a favorite of mushroom hunters, especially in the spring time in
lowland, hardwood forests. A prolific producer on a wide array of
substrates, strains of this species are plentiful and easy to grow.
Enjoying a worldwide reputation, specimens of extraordinary size have
been collected from the wild. For instance, in the fall of 1998 near
the north coast of Sicily, Salvatore Terracina, a farmer, collected a P. ostreatus nearly
8 ft. in circumference, 20 inches thick, and weighing 42 lbs.! For the
prepared and strute cultivator, cloning this monster could have
resulted in an extraordinarily productive strain.
Mycelial Characteristics: Whitish, longitudinally radical, soon becoming cottony, and in age
forming a thick, tenacious mycelial mat. Aged mycelium often secretes
yellowish to orangish droplets of a metabolite which is a toxin to
nematodes. This metabolite deserves greater study.
Microscopic Features: This mushroom produces white, to slightly lilac, to lilac grey spores.
Suggested Agar Culture Media:
Malt Yeast Peptone Agar (MYPA), Potato Dextrose Yeast Agar (PDYA),
Oatmeal Yeast Agar (OMYA), or Dogfood Agar (DFA). Optimal growth seen
at pH 5.5-6.5.
Spawn Media: Rye, wheat, milo,
sorghum, corn, and millet. Sawdust spawn in not needed for indoor
cultivation methods. However, sawdust spawn is ideal in the inoculation
of stumps and logs in outdoor settings.
Substrates for Fruiting:
A wide array of agricultural and forest waste products can be used,
including but not limited: straw (wheat, rye, oat, rice, and barley
straw); corn stalks, sugar cane bagasse; coffee pulp; banana waste;
cotton waste and cottonseed hulls; hardwood sawdusts; pater
by-products; soybean waste; palm oil by-products; agave waste; and even
the pulp remaining from tequila production! The pH at make-up can vary
between 6.0-8.0 but should fall to an optimum of 5.0 at fruiting for maximum biomass production.
Martinez et al. reported yields of
132% biological efficiency (4 flushes) from coffee pulp that was
fermented for 5 days, pasteurized, and inoculated with wheat grain
spawn. Further, they found residual caffeine from the spent substrate
was reduced by more than 90%. (Caffeine represents a signigicant toxic
waste to streams in coffee growing regions of the world).
Martinez-Carrera validated the results with yields in excess of 100%
biological efficiency in the same substrate adn presented the first
model for utilizing this abundant waste product.
published studies on the utility of cotton straw as a substrate for
this mushroom. Their yields average 600-700 grams per kilogram of dry
cotton straw, in other words 60-70% biological efficiency.
75-200% biological efficiency, greatly affected by teh size of teh
fruitbodies harvested, and the number of flushes orchestrated.
- Incubation Temperature: 75* F (24* C)
- Relative Humidity: 85-95%
- Duration: 12-21 days
- CO2: 5000-20,000 ppm
- Fresh Air Exchanges: 1 per hour
- Light Requirements: n/a
- Initiation Temperature: 50-60* F (10-15.6* C)
- Relative Humidity: 95-100%
- Duration: 3-5 days
- CO2: <1000 ppm
- Fresh Air Exchanges: 4-8 per hour
- Light Requirements: 100-1500 lux
- Temperature: 60-70* F (10-21* C)
- Relative Humidity: 85-90%
- Duration: 4-7 days
- CO2: <1000 ppm
- Fresh Air Exchanges: 4-8 per hour
- Light Requirements: 1000-1500 lux
3-4 crops, 7-14 days apart, over 45-55 days.
The Oyster mushrooms are the easiest to grow. Disadvantages of their
cultivation are in their short shelf life, post harvest, and the health
problems posed by the prolific spore load generated within the confines
of the growing room.
Cold and warm weather strains of this mushroom are widely in use. The above described temperatures for initiating P. ostreatus
are based on cold weather strains. Strains evolving in warm
geographical niches behave more in accordance with the parameters
outlined for Pleurotus pulmonarius.
Pleurotus ostreatus is
an extraordinarily interesting mushroom from many viewpoints. Highly
tolerant and responsive to carbon dioxide levels, Zadrazil noted that
mycelial growth peaks at 280,000 ppm or 28% CO2. Unless CO2 levels are
reduced to less than 1000 ppm (.01%), noticeable malformations of teh
fruitbidies occur: typically long stems and small caps. In fact, the
cap-to-stem ratio is an accurate measurement of atmospheric carbon
dioxide levels in the growing room and is used as a visual cue by
Oyster cultivators for increasing air exchange.
species is also super-sensitive to light levels. In low light, a
similar effect to that seen under elevated carbon dioxide conditions is
induced. When exposed to high light levels, pigmentation of the cap is
usually enhanced. Blue strains become bluer. Brown capped strains
become a richer brown. Similar results are also seen at lower end
temperatures give constant light conditions.
Thorn and Barron first noted that P. ostreatus
exudes a metabolite toxic to nematodes. As the nematode lies stunned,
the mycelium soon invades through one of its orifices, quickly
consuming the internal organs. From an evolutionary viewpoint, this is
remarkable that a saprophytic mushroom can become predatory to an
animal in its quest for new sources of nitrogen. This may well explain
why nematodes have never been reported as a pathogen in Oyster mushroom
cultivation whereas their occurrence in the cultivation of the Button
Mushroom (Agaricus brunnescens) is economically devastating and commonplace.
(Information taken from Growing Gourmet and Medicinal Mushrooms, Paul Stamets)