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Pure Mushroom Culture: A Bit of Tissue in a Sterile Tube, Duggar 1905
Spawn makers once relied on "virgin spawn" found by chance. B. M. Duggar of the USDA showed in 1905 that a small piece from inside a young mushroom, laid on sterilised manure in a cotton-plugged tube, grows out into a pure culture of its mycelium. You pick the mushroom, so you pick the strain. Duggar records rapid growth this way for the field mushroom and the oyster mushroom among others.
Source: Duggar, The Principles of Mushroom Growing and Mushroom Spawn Making, USDA Bureau of Plant Industry Bulletin 85 (1905), pp. 18-23 and 53-55. The picture is his Plate VI, fig. 2.
Intermediate
3 weeks
Instructions
1
1
Clean and plug the tubes
Clean and plug the tubes
Clean large test tubes or wide-mouthed bottles and plug them with cotton. If you can, heat them dry at about 150 °C for nearly an hour first. Duggar calls this not essential in rough work.
Tools needed:
Test Tubes
Glass Jar
Cotton Wool
Drying Oven2
2
Fill with manure
Fill with manure
Fill each tube about two-thirds with manure (half-decayed leaves also work) and plug it again. Fresh stable manure suits the mycelium. Dry or air it first if it is very wet, and do not use manure from grass-fed animals.
Materials for this step:
Fresh Stable Manure1 as requiredTools needed:
Test TubesCotton Wool3
3
Sterilise
Sterilise
Steam the tubes at about 15 lb pressure for 15 to 30 minutes. Without an autoclave, boil them at 100 °C for at least an hour on each of two or three days running.
Tools needed:
Benchtop Autoclave4
4
Choose and wash a mushroom
Choose and wash a mushroom
From a bed in full bearing, take a mushroom with the qualities you want: size, quality, how freely the bed bears. Take it as young as possible, best with the veil still intact. Wash it so it gives off no dust.
Materials for this step:
Mushroom1 pieceTools needed:
Water5
5
Move tissue into the tubes
Move tissue into the tubes
Work in a room without draughts or falling dust. Flame the scalpel or forceps in a gas or spirit-lamp flame. Break the mushroom open lengthwise and lift small bits from the inside. Drop one into each tube, holding the tube nearly level, and replug it at once. Nothing unsterilised may touch the tissue or the plug.
Tools needed:
Scalpel
Tweezers (Laboratory)
Alcohol Burner (Spirit Lamp)Test Tubes6
6
Let it run
Let it run
Keep the tubes out of the dust at about living-room temperature. Growth shows in a few days, is clear in a week or more, and in three weeks has spread through the medium. Failures are usually an old mushroom, a poor medium or bacteria.
Tools needed:
Room Thermometer7
7
Use it as the starter
Use it as the starter
A fully run tube is a pure culture, ready to inoculate spawn; one tube can start several lots. Start again from fresh tissue rather than passing culture on from tube to tube: Duggar warns that continued transfers weaken the spawn.
Tools needed:
Test TubesThis blueprint makes
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