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AK1000
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Registered: 06/06/16
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If the bottom of an agar plate is yellowing, does that mean it's probably contaminated?
#23631160 - 09/10/16 12:29 AM (7 years, 4 months ago) |
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Some of my original agar plates (pasty plates, to be more accurate) that I let just grow forever are turning yellow. They are normally green due to green food coloring but the bottom of them look yellow. These were originally from a MS syringe which was definitely not very sterile, but I'm wondering if the yellowing would have happened normally even if it was only pure cubensis mycelium growing? Cause I have made several transfers by now and they look very clean. I'm just wondering if they will ALL yellow eventually or is that just a sign of bacteria. Thanks!
Edited by AK1000 (09/10/16 12:30 AM)
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mushpunx
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: AK1000]
#23631235 - 09/10/16 01:21 AM (7 years, 4 months ago) |
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Well if youre talking about germination plates you let grow out it wouldnt surprise me if they were dirty plates since they were i nnoculated with spore syringe.
But without a photo my guess is the yellowing you are seeing thru the bottom is just the change in color of the agar as the mycelium grows down and colonized thru the whole plate.
To keep plates clean once you have a clean culture, refrigerate them before the culture colonizes the whole plate... size of a half dollar or so is fine. Then when you pull the culture out you can let it sit a couple days and check the plate for contams that may have snuck in
When a culture has been in cold storage for a long time I almost always put a transfer to a new plate to be safe
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herrenvolk


Registered: 05/14/16
Posts: 222
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: mushpunx]
#23631263 - 09/10/16 01:52 AM (7 years, 4 months ago) |
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How long can you leave a plate in cold storage? Does it need any GE in the fridge, or can you seal it, say, in a zip lock bag?
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mushpunx
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: herrenvolk]
#23631306 - 09/10/16 03:08 AM (7 years, 4 months ago) |
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A loose Zip lock is fine, helps them stay clean. Soft pack lunch boxes will act like a thermos and help against temperature swings.
Slants can stay in cold storage for years. Plates for a few months.
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wtfcrazymofo
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: AK1000]
#23631345 - 09/10/16 04:10 AM (7 years, 4 months ago) |
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The mycelium might be eating the green food coloring. w/o pic is just guessing.
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AK1000
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Registered: 06/06/16
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: wtfcrazymofo]
#23631379 - 09/10/16 05:02 AM (7 years, 4 months ago) |
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I didn't post a pic because nothing remarkable can be seen except the bottoms look uniformly yellow. I thought maybe this was a common occurrence but I'm not certain now.
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mrmazdarx9
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: AK1000]
#23631382 - 09/10/16 05:09 AM (7 years, 4 months ago) |
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Pics no matter how remarkable will help with diagnosis depending on the agar used it may have a tinge of yellowishness maybe drying out or something mine always looks sort of very faint yellow bearly noticeable though definitely not completely crystal clear though If they've been sat for ages probably going dry
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Psilosoulful

Registered: 09/05/14
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: mushpunx]
#23631467 - 09/10/16 07:02 AM (7 years, 4 months ago) |
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Quote:
mushpunx said: But without a photo my guess is the yellowing you are seeing thru the bottom is just the change in color of the agar as the mycelium grows down and colonized thru the whole plate.
That's what I was thinking too. I see the same thing happen to my pasty plates when I leave them overgrown for a few weeks
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AK1000
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: Psilosoulful]
#23632392 - 09/10/16 01:19 PM (7 years, 4 months ago) |
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Quote:
Psilosoulful said:
Quote:
mushpunx said: But without a photo my guess is the yellowing you are seeing thru the bottom is just the change in color of the agar as the mycelium grows down and colonized thru the whole plate.
That's what I was thinking too. I see the same thing happen to my pasty plates when I leave them overgrown for a few weeks
Interesting. I wonder if I used blue food coloring next time, if it will still turn yellow or a different color?
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Psilosoulful

Registered: 09/05/14
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: AK1000]
#23633058 - 09/10/16 04:33 PM (7 years, 4 months ago) |
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Quote:
AK1000 said:
Quote:
Psilosoulful said:
Quote:
mushpunx said: But without a photo my guess is the yellowing you are seeing thru the bottom is just the change in color of the agar as the mycelium grows down and colonized thru the whole plate.
That's what I was thinking too. I see the same thing happen to my pasty plates when I leave them overgrown for a few weeks
Interesting. I wonder if I used blue food coloring next time, if it will still turn yellow or a different color?
Yes, food coloring doesn't make a difference. It'll turn light yellow to whitish either way
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Boogieman47
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Registered: 03/05/16
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: Psilosoulful]
#23633337 - 09/10/16 05:58 PM (7 years, 4 months ago) |
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like this ? Itsjust the myc consuming the nutes and coloring every agar plate will do it
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AK1000
Stranger



Registered: 06/06/16
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: Boogieman47]
#23635093 - 09/11/16 09:26 AM (7 years, 4 months ago) |
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noob47: Yep! The underside looks like the first pic of yours exactly!
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Boogieman47
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Registered: 03/05/16
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Re: If the bottom of an agar plate is yellowing, does that mean it's probably contaminated? [Re: AK1000]
#23636126 - 09/11/16 03:27 PM (7 years, 4 months ago) |
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The green plates are the same you see how healthy the myc is ? Unless you see dark spots underneath or a greyish slimy look don't stress it
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