Incubating the sawdust spa vn bags

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Unlike nullified sawdust, most sawdust bags contacting each other during incubation grow out without contamination. The laboratory space can be maximized with sawdust spawn.

Figure 128. Sealing the bag of sawdust after inocu lation with grain spawn.

atmosphere nearly matching the volume of the sawd st. (At least 25% air space should be 1 lotted per spawn bag; otherw:"e anaerobic activity will be encouraged.)

The open bag is laid horizontally, with its opening overhanging the heating element. Grasping both the left and right outside si faces the bag opening is pullec Dpen to catch the sterile wind. A "Spock-like" finger position keeps the bag maximally inflated while the heat sealer joins the plastic. (See Figure 126.) Two strokes are often necessary for a continuous seal. By gradually increasing the duration of the seal, an ideal temperature can be found. Since the plastic liquifies upon contact with the heating element the bags should not be squeezed during sealing.

Pinholes or small tears cause the bags to collapse Collapsed bags contaminate with alarming frequency A simple test determines

Figure 128. Sealing the bag of sawdust after inocu lation with grain spawn.

1 igure 129. Dispersing the spawn throughout the sawdust by shakir g. The inflated bag not only facilitates shaking, but provides a sufficient atmospheric plenum within each bag, accelerating the growth of the mushroom mycelium-

By placing a small thermometer between the two faces of the touching bags, the laboratory manager can track temperatures to be sure they do not stray into the danger zone of >95° F. (35° C) Above this temperature, thermophilic fungi and bacteria reign.

In 3 days, recovery from the concussion of inoculatior is clearly visible from the grain kernels. The kernels become surrounded by fuzzy mycelium. Looking at a population of bags on a shelf from afar quickly tells the laboratory manager how even the spawn run is. Concentrated pockets of growth, adjacent to vast regions of no growth, lesult in poor completion. If evenly inoculated, the sawdust spawn is ready to use within two weeks.

Sawdust spawn is used for one of five pui poses:

L to sell to log growers

S to inoculate outdoor beds by dispersing the spawn or by burying the block into the ground.

□ to inoculate sterilized hardwood dowels in the creation of plug spawn for log and stump growers

□ to grow mushrooms on. (However, most of the species described in this book benefit from having the sawdust enriched with a readiiy avai'able, nitrogenous supplement such as bran )

□ to inoculate 5-20 times more sterilized enriched sawdust, usually sawdust supplemented with ni'rogenous sources such as rice bran, soy bean flour, etc.


When sawdust is supplemented with a nitrogen-r ;h additive, the yields of most wood-decomposers are enhanced substantially. Rice bran is the preferred additive in Asia. Most brarjs derived from cereal grains work equally well. Rye, wheat, corn, oat, and soybean brans are commonly used. Flours lack the outer seed coat and, by weight, have proportionately more nutrition than brans. Other more-concentrated nitrogen sources such as yeast, soy oil. and peptone require precise handling and mixing at rates more dilute than bran supplements. The nutritional tables in Appendix V will help cultivators devise and refine formulas. Mini-trials should be conducted to prove suitability prior to any large-scale endeavor.

For the cultivation of Shiitake {Lentinula edodes), Enokitake (.Flammulina velutipes), Maitake (Grifola frondosa), Karitake (.Hypholoma sublateriiium), Lion's Mane (Hericium erinaceus), The Black Poplar {Agrocybe aegerita), and Nameko (.Pholiota nameko), the following formula is recommended. Alterations to the formula

Cultivation Hericium

Figure 130. Components tor the iruiung sawdust, chips, and bran.

Figure 130. Components tor the iruiung sawdust, chips, and bran.

Figure 131. Adding the supplement (bran) to hartf wood sawdust will further enhance yields for each strain. I find this formula to be highly productive and recommend it highly

The base substrate is composed of fast- t composing hardwoods, such as alder, poplar, ancc tton 'ood in contrast to the slow-rotting woods like oak and ironwood. If these types of quick-rotting woods are unavailable, deferment should first be made to the tree types upon which the mushroom species natively int oits. Most of the photographs in this book are from blocks made with this basic formula.

I have devised the following fruiting formula utilizing hardwood sawdust, hardwood chips, and a nitrogen-rich supplement, i s ca~s rice bran. Water is added until 65-75% moisture is achieved, a few percentage points below saturation.

Figure 131. Adding the supplement (bran) to hartf wood sawdust

This formulation is designed for maxu iz ing yields of wood-decomposers. Most gourmet and medicinal mushroom produce prolifically on this substrate. If wood is a scarce commod'y and not available as abase component, please refer to Chapter 18.

The Sawdust/B in Fn: "ng


100 pounds sawdust 50 pounds wood chips (1/2-4 inches) 40 pounds oat, wheat, or ri e bran 5 -7 pounds gypsum (calcium sulfite) By dry weight, the fraction of bran is approximately 20% of the total mass. By volume

Figure 132. Adding 2-3" diameter wood chips on top which builds the matrix.

this formula is equivalent to 64 gallons sawdust 32 gallons wood chips 8 gallons bran

1 gallon gypsum (calcium sulfate)* The above-mentioned mixture fills 160-180 bags of moist sawdust/bran to a wet mass be tween 5.0 and 5.5 lbs. I recommend using a standardized volumetrr u~ut for ease of handling, anything from a plastic 4-gallon bucket to the scoop bucket of a front end loader. In either case, simply scale up or down the aforementioned proportions to meet indivlual needs. Thorough mixing is essential.

The above weights of the sawdust and chips are approximate, based on their ambient, air dried state. (The wood used, in this case, is red alder, Alnus rubra, and is highly recom mended.) Bran should be stored indoors, away from moisture, and off the ground to prevent

Figure 133. The ingredients are thoroughly mixed.

souring. Rice bran readily contain1 nates and must te carefully handled. Molds and bacteria flourish in nitrogen-rich supplements soon after exposure to moisture.

Using a four-gallon bucket as a measurement unit, 16 buckets sawdust, 8 buckets chips, and 2 buckets bran lie ready for use All three are mived thoroughly together in dry form then gypsum is added, and the final mixture is * Raaska (1990) found that the use of calcium sulfate (gypsum) stimulated mycelial growth of Shiitake in a liquid media supplemented with sawdust. The calcium sulfate did not, by itself, significantly affect pH at make-up. However, mycelial growth was stimulated by its addition, and there was a corresponding precipitous decline of pH and a four-fold increase in biomass vs. the controls. Leatham & Stahlman (1989) showed that the presence of calcium sulfate potentiated the photosensitivity of the Shiitake mycelium, affecting fruitbody formation and development. A beneficial effect of calcium sulfate on the growth rate of other wood decomposers is strongly suspected moistened to 60-65%.This formula makes H 180 bags weighing 5.5 lbs. Directly after make-up the bags are loaded into the autoclave for sterilization Should the n::xture sit for more than a few hours, fermentation reactions begin. Once bacteria and molds flourish, the mixture is rendered unsuitable.

If alder is unavailable, I strongly encourage substituting other rapidly decomposing rard-woods, such as cottonwood, poplar, willow, sweetgum, and similar wood types from riparian ecosystems Although oak is the wood most widely used in the cultivation of Shiitake, Maitake, and Enokitake, its inherent, slower rate of decomposition sets back fruiting schedules compared to the above mentioned hardwoods. Sycamore, mahogany, ironwood, the fruit trees, and other denser woods require a

Figure 134. The mixture featured in Figures 1^0--33 c 'ated 180 6 lb. bags of the fruiting formula. Once mixed and wetted, this mixture must be immediately loaded into the autoclave and sterilized.

longer gestation period, although subsequent frui'ings may benefit from the increased wood density.* Here, a iittle experimentation on the part of the cultivator could have far-reaching, profound results Mini-trials matching the strain with the wood type must be conducted before expanding into commercial cultivation.

By laying out the sawdust first in a 10 x 10 foot square- the chips can be thrown evenly upon ttfl sawdust, and topped by broadcasting rice bran evenly over the top. This mass is mixed thoroughly together by whatever means available (fiat shovel, cement or soil mixer, tractor). A mixer of less than a cubic yard in capacity is probably not more efficient than one person mixing these three ingredients by hi rith a shovel. Pockets of discoloration, mold, or "clumps" should be avoided during the making up of this composition. The more competitors at make-up mean the more that are likely to survive the "sterilization" cycle

Mixing the above components by hand be comes functionally impractical beyond 300 bags per day. At this level of production and above, automated mixing machines and bag fillers, adapted from the packaging and nursery industry are far more efficient in terms of both time and, in most cases, money invested

Figure 134. The mixture featured in Figures 1^0--33 c 'ated 180 6 lb. bags of the fruiting formula. Once mixed and wetted, this mixture must be immediately loaded into the autoclave and sterilized.

Wetting the substrate to its proper moisture content is critical to creating a haoitat that encourages mycelial growth while retarding

* If speed of production is not the over-riding isfle, then i ny of these denser hardwoods, such as tne oaks, may produce better-quality fruitings over the long term than those from the rapidly decomposing j- dwoods. However I have found Enokitake, Oyster, i eishi, Lion's Mane and Shiitake to give rise to faster fruitings of equally superior quality on alder, poplar and cottonwood.

Figure 135. Commercial double door steam sterilizer balanced substrate, moisture content can be fairly accurately determined by touch. Materials are measured volumetrically, correlated to weights, for ease of handling. This insures that the mixing proceeds with speed and without unnecessary interruption.

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