If you did want to start a culture, it is better to use agar plates. In a liquid medium, you cannot propagate prime growth patterns or isolate contams.

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-ChesterCopperpott-
"Old enough to know better, Young enough to do it anyway."

Technique #1 Would be to wait for the mushrooms to grow and then use a TEK (found in the Grow/Find Section) and take spore prints and then make syringes.

Technique #2 is to pre-prepare some substrate to use, then when the mushrooms are mature pick a nice healthy looking one (do all of this under sterile conditions) and cut the stem open. If you wish you can blenderize the piece (in a sterile blender) with some water and use the resulting mycelium water to innoculate your prepared substrate filled jars, or you can just take the section cut it up and place it into your prepared jars.

Mushrooms are merely densly packed Mycelium (for the most part). If you use steril conditions you should be able to use both techniques. Cut the cap off the mushroom and take prints and at the same time, take the stem, find a nice clean healthy section and use that to innoculate more jars.

Good Luck