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SBSP
Stranger
Registered: 08/10/20
Posts: 5
Last seen: 3 years, 5 months
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Yellow droplets on my agar plate
#26879989 - 08/14/20 11:24 AM (3 years, 5 months ago) |
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I'm new to growing mushrooms and I'm trying to grow store bought king oysters.
After about a week some yellow droplets started for form. Google says its skin bacteria. Is it dangerous. ?

Initially I out some agar potato starch dishes in a PC but they melted. So then I just boiled the mixture in a microwave and poured it in. after it cooled down I stuck a piece of king oyster onto the agar. So yes the sterilization didnt quite go according to plan.
Not sure if I have now cooked up something dangerous,
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Roger Clemency
Smile


Registered: 03/23/20
Posts: 2,005
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Re: Yellow droplets on my agar plate [Re: SBSP]
#26880013 - 08/14/20 11:46 AM (3 years, 5 months ago) |
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I don’t know anything about that bacteria, though if you just transfer to a clean plate you’ll be alright.
Did you buy pre sterilized plastic Petri dishes? If so all you need to do is mix your agar in a glass bottle of some kind and PC that for 25 min or so at 25psi and then pour it into your plates in a SAB
-------------------- Sour grapes, sweet revenge Heaven starts right where hell ends
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SBSP
Stranger
Registered: 08/10/20
Posts: 5
Last seen: 3 years, 5 months
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Thanks for the reply. The dishes came in a normal plastic bag, I didn't look like it was pre-sterilized.
I think for now I'm going to stick with small plastic tubs meant for contact lenses with screw on lids and polyfill. The plastic is made of PP5 and survives the PC. It allows me to cook them with the agar already in it..
All of the ones I put in the small tubs seems to be doing well with no contam.
Edited by SBSP (08/14/20 12:06 PM)
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Martinsapin
no-mad



Registered: 09/12/16
Posts: 310
Loc: Canada
Last seen: 1 year, 7 months
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Re: Yellow droplets on my agar plate [Re: SBSP]
#26880162 - 08/14/20 01:32 PM (3 years, 5 months ago) |
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Quote:
SBSP said: I'm new to growing mushrooms and I'm trying to grow store bought king oysters.
After about a week some yellow droplets started for form. Google says its skin bacteria. Is it dangerous. ?

Initially I out some agar potato starch dishes in a PC but they melted. So then I just boiled the mixture in a microwave and poured it in. after it cooled down I stuck a piece of king oyster onto the agar. So yes the sterilization didnt quite go according to plan.
Not sure if I have now cooked up something dangerous,
WOW ok dude
just follow the regular steps of agar making you ll be fine
pc plastic petri, dont do it dont microwave it either
10gr agar 10 gr malt extract 500 mL tap water make 20 standard petris
45min at 15 psi let cool down inside pc for 2 hours
pour it inside a SAB.
If not clear enough read one of the numerous Teks of watch RR video.
-------------------- looking for a sclerotia producer print
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Rhizomorph
Psychedelic Researcher



Registered: 04/24/20
Posts: 785
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Re: Yellow droplets on my agar plate [Re: SBSP]
#26880231 - 08/14/20 02:14 PM (3 years, 5 months ago) |
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As Roger mentioned you can just transfer a clean section of mycelium to a clean plate.
The issue for you is that that plate was not clean. Microwaving the agar will not sterilize it (there are heat resistant endospores in the potato starch that will only die under high pressure + heat such as a pressure cooker)
You obviously cannot pressure cook the plastic petri dishes since they will melt, but they come pre-sterilized in the package so you don't need to worry about sterilizing/pressure cooking them.
What you should do is prepare your agar mixture in a glass bottle of some sort (you can microwave it to liquify it, but not to sterilize it) and then put this in the pressure cooker with the cap slightly loose.
Once this is done & the pressure returns to 0psi, put the glass bottle in a Still Air Box (SAB) with the petri dishes, and pour the agar mixture into the petri dishes. At this point the agar may solidify if it gets too cool but since it is already sterile you can put the glass bottle in the microwave to liquify it again so you can pour it. You generally want it hot but not scolding hot.
Here's a more thorough TEK Bod wrote up for this process: https://www.shroomery.org/forums/showflat.php/Number/21922023
Alternatively, no-pour methods such as the one in my signature are a very easy way to make sterile agar (the plastic dishes are made of PP5 plastic which won't melt in the pressure cooker + you can reuse them instead of throwing them out after each use)
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sendmehummus
AT Hiker


Registered: 08/03/20
Posts: 383
Loc: USA
Last seen: 2 years, 3 months
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Re: Yellow droplets on my agar plate [Re: Rhizomorph]
#26880319 - 08/14/20 03:20 PM (3 years, 5 months ago) |
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I had the same spots on some old king plates and the KO myc devoured that weak bacterial bastard. If thats all you got on that plate you should be golden errr white after one transfer 👍
-------------------- Be patient and keep it simple.
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