Bioremediation

We provide spawn and also “grow your own mushroom kits” for a variety of species. This picture shows our shiitake blocks six days after being soaked.

Specialty Mushrooms

The button mushroom has dominated the North American market for a long time. However, in other parts of the world other species (considered 'exotics' in North America) are common. Since many of these have great flavour, and also possess beneficial medicinal properties, their popularity is increasing. Some species can now be found in North American specialty food stores or in larger supermarkets. However, their price is high, and the quality is often not good.

Mushroom growing can be a fascinating hobby or even a career. Some basic knowledge of the mushroom's biology is helpful. Mushrooms are different from the organisms with which most people are familiar; They are actually different enough that taxonomists place them in a Kingdom by themselves.  One of their key characteristics is that their cells are filamentous. These cells are called "hyphae". Fungi are Nature's great recyclers, getting their energy by degrading organic matter that was accumulated by other living things. For example, most of the edible mushrooms that are discussed here grow on wood, or other cellulosic materials like straw or paper, or on these materials after they have been composted. To grow, the fungal hyphae extend into the substrate where they excrete enzymes that break it down into nutrients. The fungus then absorbs and uses these nutrients to produce more hyphae until an extensive network of hyphae (called the "mycelium") extends through the substrate. After some period, and under appropriate conditions, the cells of the mycelium grows into knot-like aggregates of cells called "primordia". These differentiate further and expand into mushrooms.

Mushroom growing basically involves managing conditions so that the desired fungal species (e.g. shiitake, oyster mushroom, etc.) out-competes other microbes (e.g. bacteria or undesirable fungi) that may also be trying to colonize the substrate. One of the first steps is often to eliminate propagules of the competitors. This can be done by, for example, heating the substrate. After the competitors are eliminated, a pure culture of the desired fungus is added. This pure culture is produced in a lab, and consists of mycelium growing on a carrier like grain or sawdust that has been sterilized. It is called "spawn".

After the spawn is added to the substrate, conditions are adjusted to favour its growth. When the substrate is completely colonized by mycelium, conditions are changed so that primordia form. Further management is required so that these grow into high quality mushrooms that can be eaten or marketed.


If done well, mushroom production can be a business. However, it is also an art. With some species, success may happen the first time, while with others it might take many trials (and errors) to identify the correct conditions. After about twenty years of work, we now have many successes, but still encounter 'challenges'. This is what keeps us interested in the business..

As a rapid way in to the mushroom's Kingdom, try one of our "Grow-Your-Own Shiitake" kits. About a week after receiving it you will be eating delicious mushrooms you have grown yourself. Our kits are chemical-free, containing only mycelium of a productive strain, along with enough wood and organic nutrients for 2 to 5 mushroom crops (called "flushes"). If managed properly, the first flush will give about 1 pound of mushrooms per kit. Subsequent flushes are usually smaller, but the total yield may be over two pounds per block.

If you want to go further into the mushroom Kingdom, an Internet search for e.g. "shiitake", "oyster mushrooms", "maitake", "reishi" or "specialty mushrooms" will give lots of information. You will also find useful books. Growing Gourmet & Medicinal Mushrooms by Paul Stamets (Ten Speed Press, CA) is very informative. There are many others.

Growing Shiitake.
If you decide you want to produce mushrooms commercially, we can help. Shiitake is probably the best species with which to start.. It is quite easy to grow, has a good shelf life, is great tasting, and there is a fairly good market for it. There are two basic approaches to growing it.

On logs.
The traditional method is to grow it on hardwood logs. Oak has been the main species used, but almost any hardwood (and some softwoods) also work. Photo 1 shows shiitake growing on birch. We have also had success with alder, white birch, silver birch, red maple, sugar maple, ironwood and beech.  It seems probable that with experimentation, almost any species could be used.

Success comes from getting the details right, but the basic idea is to cut healthy trees, and then introduce a pure culture of the shiitake (i.e. spawn) into ca 4 ft long pieces of log cut from the tree. Steps should be taken to insure that competing fungi do not attack the wood. For example, chose trees that are not already infected by decay fungi. Be careful not to damage the tree bark. Keep the logs away from sources of fungal contaminants like the soil.

Within a few weeks of cutting, the logs are inoculated. For this, the normal procedure is to push spawn tightly into holes that are drilled in the logs. The holes are then sealed using hot wax or foam plugs. Holes are normally drilled in an elongated diamond pattern over the log so that the distance between them does not exceed about 10 inches. Since the mycelium grows faster in the longitudinal direction than in the radial one, the holes should be closer together around the log circumference than in the longitudinal direction. Drilling more holes is better, but this obviously takes more work, and uses more spawn.


After inoculation, the logs are kept in a sheltered (not sunny) area. Logs should be periodically weighed to ensure the wood in them remains moist. Between 0.6 and 1 kg of water per dry weight of wood (60-100%) water is good. The logs should not contact the soil since other fungi and insect larvae might then enter them. After about a year, the mycelium will have grown through the logs. Mushrooms can then be induced to form by "shocking" the logs. This is usually done by submerging them in water for a few days, and then standing them upright, leaning against a suitable frame. Within about a week, the mushrooms will emerge through the inoculation holes (first crop) or through the bark (subsequent crops). Cropping can occur about twice per year for as many as five years, depending on the tree species used and size of the log.

On sawdust medium, or "blocks"
In the newer method (which most commercial growers use) the shiitake is produced indoors on blocks. For this, nutrient-fortified sawdust is placed into special purpose plastic bags, sterilized, and inoculated with shiitake spawn. During an incubation period, the mycelium grows through the sawdust, knitting it together. The bag can then be removed, or it may be left on for an additional period. In either case, the mycelium will continue to grow in the sawdust medium, eventually transforming it into a solid mass, covered with a bark-like, dark brown skin - It is a bit reminiscent of a football. This is called a "shiitake block". To produce the mushrooms, the blocks are shocked (usually by soaking) to induce them to form mushrooms. Blocks usually form about one pound of shiitake in the first crop or flush. They will give a number of additional flushes at about one week intervals until a yield of over two pounds (fresh weigh) of mushrooms is obtained. Depending on how the blocks are managed, mushrooms can attain a very large size (see photo 2). If you wish to produce blocks, you might read an article by Boyle, 2001. Developing high yield shiitake blocks. Mushroom World. 13(3)

We can also provide spawn or blocks for a variety of other mushroom species. These include oyster mushrooms in a variety of colors (see for example the golden oyster mushrooms, P. citrinopileatus, in photo 3), the beautiful lion's mane mushroom (Hericium coralloides, photo 4), and maitake (Grifola frondosa, photo 5), and Reishi (Ganoderma lucidum, photo 6).

If you are interested in buying blocks or spawn, or in our consulting services, please contact mboyle.silk@gmail.com.

If you are interested in mushroom forays or workshops, see the Nova Scotia Mycological Society's site at  http://www.nsmushrooms.org/.

Some of our publications about mushrooms.

Boyle, D. 2001. Developing high yield shiitake blocks. Mushroom World. 12(2):7-15.

Boyle, D. 1999.Why mushrooms are not wiped out by green mould. Mushroom World.10(4):5-10.

Boyle, C.D. 1998. Nutritional factors limiting the growth of Lentinula edodes and other white-rot fungi in wood. Soil Biol. Biochem. 30:817-823.

Bioremediation

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