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 johnny_poke
Brownian movement
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 3 week old agar still good? 
#9536729 - 01/03/09 07:29 AM (3 years, 4 months ago) |
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I mixed up some potato/honey/agar about 3 weeks ago and it's been sitting in a foil covered meauring jug in the fridge since then. I imagine that if I pour it into dishes and the PC it it will be sterile... but will the nutrient content still be OK?
Thanks for reading 
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[quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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 Pinback
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Re: 3 week old agar still good? [Re: johnny_poke]
#9537254 - 01/03/09 10:00 AM (3 years, 4 months ago) |
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Assuming there is nothing else growing in it; yes. If there is, it might still work.
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johnny_poke
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Re: 3 week old agar still good? [Re: Pinback]
#9537276 - 01/03/09 10:10 AM (3 years, 4 months ago) |
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OK great. Someone here had warned me about the perils of leaving agar for too long, but it only seems logical that as long as nothing is growing in it the nutrient content will remain unchanged. Thanks very much for clearing that up.
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[quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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fastfred
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Re: 3 week old agar still good? [Re: johnny_poke]
#9539155 - 01/03/09 04:24 PM (3 years, 4 months ago) |
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You don't want to leave agar sitting too long because it dries out. That's only really a concern with poured agar in dishes. If nothing is growing on it just microwave it and pour away.
-FF
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denger
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Re: 3 week old agar still good? [Re: fastfred]
#9539620 - 01/03/09 05:57 PM (3 years, 4 months ago) |
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fastfred : It seems like he have not sterilized his agar to begin with. If he did, then yes, its perfectly safe. Otherwise, chances are pretty high something is already growing and consuming nutrients. Even if it is sterilized at this point its probably already off in some way.
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fastfred
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Re: 3 week old agar still good? [Re: denger]
#9541693 - 01/04/09 12:48 AM (3 years, 4 months ago) |
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LOL, I never figured somebody would make up agar and not sterilize it. Shame, shame.
Hopefully a lesson learned. If it was sterilized it should be fine in the fridge for at least several months. Probably still be fine anyways, but I wouldn't waste time and dishes on it.
-FF
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johnny_poke
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Re: 3 week old agar still good? [Re: fastfred]
#9542036 - 01/04/09 03:19 AM (3 years, 4 months ago) |
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No, I did not pre-sterilise the agar because it will be steralised in the dishes once I pour them and PC. I can see no signs of life in there at all, no smell (apart from potato) is obvious either. I'm pouring and innoculating today... so any more opinions on the matter please?
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[quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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johnny_poke
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Re: 3 week old agar still good? [Re: johnny_poke]
#9542045 - 01/04/09 03:23 AM (3 years, 4 months ago) |
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Aah, screw it...I will make up some more. Better safe than sorry eh
Thanks guys.
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[quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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German Kahuna
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Re: 3 week old agar still good? [Re: johnny_poke]
#9542062 - 01/04/09 03:35 AM (3 years, 4 months ago) |
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Why? It sounds as if it's still good. I would use it.
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"Vegetarian" [ /ˌvedʒəˈteəriən/] - Ancient slang meaning "village idiot who can't hunt, fish or ride".
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Andrew47
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As long as it was sealed and nothing has evaporated it should be perfectly fine. Any growth should be superficial on the surface anyway.
What I don't understand is ... you are pressure cooking poured petri dishes?
Interesting ...
BTW I like to "pour" my dishes with a 10cc syringe without a needle to ensure 10cc per dish same level every time
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fastfred
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Re: 3 week old agar still good? [Re: Andrew47]
#9544184 - 01/04/09 01:44 PM (3 years, 4 months ago) |
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I'm not sure exactly what you've done... did you add the agar yet? Is the media solid?
If you added the agar to the media and it solidified it should be fine. If you didn't add the agar or didn't dissolve and melt it so that it solidified it is ruined for sure. Don't use it if that is the case.
Standard practice is to pour the agar into sterile dishes after you have sterilized it. With glass dishes you can sterilize it in the dish, but I don't advise it. You are likely to lose or gain water during the process and it will throw off your mixture.
The syringe method works pretty well. I sometimes use it. When pouring my dishes I either just barely cover the bottom in order to save media or else I pour it right up to the top so that I can scope the dish with the cover on.
-FF
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johnny_poke
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Re: 3 week old agar still good? [Re: fastfred]
#9582201 - 01/10/09 09:50 AM (3 years, 4 months ago) |
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Hey, thanks for the info guys. Yes, I poured the dishes before PCing as I thought this would mean less exposure to contams than if I poured them afterwards. As it turns out PCing in the dish was prob not the best idea as alot of condensation built up. Since I MS inoculated them in a glovebox I just tipped the excess water off before swabbing the spores on. Next time I will PC the agar mix all together then pour the plates in the glovebox afterwards to avoid this. I will also use a syringe to pour them as u suggested, good idea.
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[quote]But what our scientist does not realize is that every time he makes a measurement, the Flying Spaghetti Monster is there changing the results with His Noodly Appendage.[/quote]
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German Kahuna
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Re: 3 week old agar still good? [Re: johnny_poke]
#9582251 - 01/10/09 10:02 AM (3 years, 4 months ago) |
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To avoid condensation build-up, you got to stack them on top of each other while they cool down. Condensation comes from the surrounding air being cooler than the inside of the dishes. On top of the last dish you can put a dummy dish that just contains hot water, so that the lid of the topmost dish will remain clear as well.
I also don't PC poured dishes, but I pour them inside a glove box when the agar has cooled down to almost lukewarm, practically right before the agar solidifies.
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"Vegetarian" [ /ˌvedʒəˈteəriən/] - Ancient slang meaning "village idiot who can't hunt, fish or ride".
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Dragonaut
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what about a three year old jar of agar? 
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tr8orjohn
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Re: 3 week old agar still good? [Re: Dragonaut]
#9589944 - 01/11/09 02:19 PM (3 years, 4 months ago) |
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Quote:
Dragonaut said:
what about a three year old jar of agar?
So long as its kept sterile, sure...
Another hint for condensation is keeping your plates upside down while they are incubating...keeps the moisture in the agar and not clouding up the top of your plates
-jon
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Microbiologist turned mycologist, but still amateur enough to enjoy the occasional surprise...
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Terry M said:
Looking for rules that other people use successfully. Sterile procedure is just a set of rules that work.
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fastfred
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Re: 3 week old agar still good? [Re: tr8orjohn]
#9610483 - 01/14/09 06:19 PM (3 years, 4 months ago) |
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If you do get condensation it's pretty easy to simply heat up the lids a bit with a hair dryer or heating pad. The water will evaporate from the lids and recondense on the cooler agar surface.
-FF
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didjin_d
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Re: 3 week old agar still good? [Re: fastfred]
#9610840 - 01/14/09 07:11 PM (3 years, 4 months ago) |
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You guys AGAReat! Just great I tell ya! 
Learing about physics in a petri dish. Whooda thunk it?
Anyway. What kind of dishes are you using jonny-poke? Will disposable dishes handle the pressure cooker?
-DD
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" learning how to cook will save you money, usually make you healthier, and occasionally get you laid. "
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"Most of the people who ask the question 'Do any psilocybin mushrooms grow around here?' would rather change their way of looking at reality rather than face the difficult and discouraging task of transforming reality itself"
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