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Under the mycellium there's several little black dots they're about the size of lead for a mechanical pencil (.07). you can't see them unless you look from the bottom of the plate, or cut it open as i did when i made some new petri plates (with care to avoid the dots). any help would be great as it what they are and cause. Thanks
Sometimes bacterial contaminants won't prosper in a treated petri dish, but find a nice little nook under growing mycelium. Worst case scenario, but still a possibility, is that it is an anaerobic/capnophilic bacterium that can ONLY thrive in the low O2 environment under the growing mycelium. This would also be consistent with the slow growth rate of the suspect contaminant.
No matter the case, you are 'probably' ok transferring mycelium as long as you stay away from the black points. 'Probably', meaning that the relative size and growth rate of fungal hyphae might allow a few bacterial cells to hitch a ride to the outer growth areas. If it is really an anaerobe, though, this is quite unlikely. If the antibiotic does its job, this is also quite unlikely. Another likely scenario is that it is just a black precipitate, though such things are usually much smaller than a pencil lead. If you have some more plates, it might be a good idea to attempt a tiny transfer of periphery tissue [perhaps while making some test inoculum].
**just read, you are doing transfers. . .I bet they'll be fine, take extra care to make it a small amount.
Was your agar lab grade or home brew? If it wasn't lab grade, you might have had some particles in suspension that settled as the agar cooled. As small as they are, you might not have noticed them until looking closely for contaminates. Just a thought....
-------------------- Just another spore in the wind.