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champignontete
Stranger
Registered: 11/19/17
Posts: 2
Last seen: 6 years, 4 months
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Sterilizing plastic petris - I seem to have been successful so far. Am I playing with fire?
#24793706 - 11/19/17 01:21 PM (6 years, 4 months ago) |
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Hi,
I could use your suggestions about this.
I bought a lot of plastic petris rather cheaply as they were new but non-sterile.
I had always intended to re-use them anyway, so I would have had to sterilize them at one point.
I have recently made some agar plates; To sterilize the dishes I immersed the petris in dilute bleach for 30 minutes, after which I immersed my hands (in bleach... ), lifted the dishes out (holding them open-side downwards) and immersed them in clean water to rinse them. They were then removed from the water, allowed to drip for a second or two (still held open-side downwards) and closed. Once I had done this with five of them, they were placed in my SAB and I poured agar into them and inoculated them.
I did not attempt to dry inside the dish, either the lid or the base of the dish, after rinsing them as I thought that this would add contaminants... I don't see that a few drops of water would have an adverse effect on the agar...?
The plates were inoculated 13 days ago, and the mycelium has formed a circle of between 2cm and 4cm in diameter (some dishes have colonized faster than others) One dish has been lost to contamination (green mold), however there are no signs of anything nasty lurking in the other four.
Do you think that this method of sterilization is okay (assuming that a 20% loss is acceptable to me)? If there were contamination, surely it would have shown up by now right?
Due to my not drying the dishes before pouring the agar, there is a lot of condensation on the lid, however I have made sure to avoid tilting the dishes, so it never falls onto the mycelium. This condensation seems to be slowly dissipating as the mycelium absorbs moisture perhaps.
Since it seems to be working, do you think that my technique is okay or could there be some latent horrors that will appear later on, at which point I may regret attempting to reuse plastic petris?
Thanks for your time
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bodhisatta
Smurf real estate agent
Registered: 04/30/13
Posts: 61,891
Loc: Milky way
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Re: Sterilizing plastic petris - I seem to have been successful so far. Am I playing with fire? [Re: champignontete] 1
#24793712 - 11/19/17 01:26 PM (6 years, 4 months ago) |
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Playing with fire. And all of your plates are contaminated. To a noticeable degree is the problem. There may be things that will not germinate tagging along. Or things that grow very slowly in your media or in air. And they're all embedded in the agar now.
You can be sure to avoid that with sterile plates.
Colonies growing on the top of the agar are more related to your sterile technique.
Keep one of your sanitized plates with agar in it as a control. Keep it somewhere warm like 75-85 and after 10 days view it backlight with a bright light. I bet there's small pinpoint colonies growing in ghe agar itself they could be smaller than a sentence period.
If you tried doing this using plate count agar for QA then incubated the plates at 80F both aerobically and anaerobically there would be all kinds of growths
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ellomello
XP
Registered: 08/11/08
Posts: 2,425
Loc: babilonUSA
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Re: Sterilizing plastic petris - I seem to have been successful so far. Am I playing with fire? [Re: bodhisatta]
#24793825 - 11/19/17 02:58 PM (6 years, 4 months ago) |
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i have been wondering about sterilizing plastic plates... Would boiling and steaming them achieve sterilization?
(maybe just steaming if boiling makes them melt idk)
Edited by ellomello (11/19/17 03:01 PM)
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liloldme
( ͝° ͜ʖ͡°)つ=D
Registered: 05/15/04
Posts: 5,087
Loc: Zone 8
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Re: Sterilizing plastic petris - I seem to have been successful so far. Am I playing with fire? [Re: ellomello]
#24793831 - 11/19/17 03:06 PM (6 years, 4 months ago) |
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Not worth the time IMO. It's like 80 bucks for a 500 count if you shop around.
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