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Mushroom cultivation => Cultivation => Topic started by: bigfatmouthj on March 13, 2010, 08:30:53 PM

Title: using grains without sterilizing?
Post by: bigfatmouthj on March 13, 2010, 08:30:53 PM
So i found this on another mush info site and thought id post it and see what the pros thought about this method. wonder what types besides cubes this might work for. any ideas?(again i can take no credit for this tek...wish i could  :ph34r:)

recently, while experimenting with fermented substrates, I discovered an easy way to create grain spawn without the need to sterilize anything. I am using it for Pleurotus ostreatus and Pleurotus eryngii. A few tries indicate it also works for Stropharia rugosoannulata, Coprinus comatus and cubes, perhaps also for Agrocybe aegerita. No success with Agaricus bisporus yet.

Heres what you have to do:
- Soak the grain for 24 hours.
- Cook it shortly, so the kernels wont germinate.
- Rinse it with clean water.
- Fill jars half with the cooked grain.
- Add water until filled up to three quarters.
- Remove kernels, which are floating on top.
- Close the lid loosely.
- Wait.
- Turn the jars every day or use a clean spoon and stir around.

After a few days lactic acid fermentation will start, like in bread baking with sourdough or like in bacterial contam. This time it is what we want. You will notice bubbles of air rising and a sour and fruity smell appears. Let it bubble for another few days.

Possible problems:
- If you notice a whitish film on the surface, there is yeast growing on top. Use a clean spoon and remove it.
- Some kernels will rise to the surface. If you don't move the jars, they may stay there, dry out partially and green mold can grow.
- Sometimes, When waiting too long like one or two months, other bacteria take over and produce acetic acid, which seems to be toxic for mushroom mycelium.

The PH falls from 7 to 4 and after a week or two, the grain is ready. Strain the water and inoculate with fresh and clean mushroom stems or mycelium growing in wood or straw. Use at least a spoonful and don't mix. Just put it on top. Now it will take several days for the mycelium to adapt to the low PH. The above mentioned mushroom species are known to digest bacteria, so they will happily eat whatever they find and grow vigorously and dense into the grain.

The whole process takes longer than the sterile way and needs a bigger amount of starting mycelium, but you don't need a pressure cooker, HEPA-filter, glove box and all that stuff. You can work on your kitchen table and open air. Just be clean. Of course you should keep the jars closed after inoculation, but you can safely open them from time to time, if you want to check the smell or whatever. The high amount of lactic acid and the active bacteria will prevent mold and yeast from growing, even if spores are present.

A few days after complete colonization, you can use the grain spawn to inoculate wood chips, straw or more fermented grain. Don't expect to be able to shake the jars to separate the kernels. Use a spoon to break your spawn into small pieces. When going to straw or wood chips, mix well.


Thats it for now. Have fun with this method and please post here if you find out it works for other species too. Lentinus edodes will possibly not work well, as shiitake mycelium usually separates itself from bacterial contams, building up the usual brown surface. It may take weeks, until it grows further into the fermented grain.