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RandomFX
protege


Registered: 12/02/13
Posts: 1,015
Loc: North-East, USA
Last seen: 6 years, 1 month
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Why should you PC s no pour pp5 30 minutes?
#19479083 - 01/26/14 09:39 PM (10 years, 11 months ago) |
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ok...I don;t get it, so can someone actually explain it to me? in a lot of the no pour pp5/petri dish agar tec's it says to raise temp in pc slowly, then after you put the pressure dongle on, PC for like 30 minutes..... Can someone answer me why 30 minutes?
ok, I get "We want to sterilize" so no need to say that, no duh.... but we are putting like 20-25 ml of agar into these things.... once the pressure reaches 15 psi, am I wrong in guessing the temp inside is 250 degrees? how long does it honestly take to sterilize 25 ml, which is fairly thin, even if you have ti full of pp5's or petri dishes (petris stack tighter but I imagine people put some space between them) 20-25 ml of material? doesn;t it become sterile after like 7 seconds at 250 F? or no?
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Ace1928
Experimenter



Registered: 08/09/13
Posts: 181
Loc: NSW
Last seen: 6 years, 1 month
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Re: Why should you PC s no pour pp5 30 minutes? [Re: RandomFX]
#19479099 - 01/26/14 09:43 PM (10 years, 11 months ago) |
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From personal experience Ive found that a minimum amount of time is about 15 minutes. But I ALWAYS put it in for the 30 because i have had a few times where a particularly tough contam has survived the 15 minutes. I havent had a single control plate get contaminated at the 30 minute sterilisation though.
You can easily verify it by testing it out yourself.
-------------------- Only by embracing that which mother nature has supplied to us can we hope to ever peacefully exist on this planet
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RandomFX
protege


Registered: 12/02/13
Posts: 1,015
Loc: North-East, USA
Last seen: 6 years, 1 month
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Re: Why should you PC s no pour pp5 30 minutes? [Re: Ace1928]
#19479172 - 01/26/14 10:04 PM (10 years, 11 months ago) |
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Quote:
Ace1928 said: because i have had a few times where a particularly tough contam has survived the 15 minutes.
well then....thats good enough for me, I suppose. I wouldn't/didn't think/of thought something could survive that long at those temps. I thought if it was something larger, like a beaker full, maybe it took that long for the temp inside to reach 250, but didn't see 20 ml or 25 ml taking all that long. but if it can and has then it makes sense to do it the 30 minutes. now I know.
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Sgt. Pepper



Registered: 06/19/13
Posts: 2,551
Loc: Third Stone From The Sun
Last seen: 3 months, 15 days
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Re: Why should you PC s no pour pp5 30 minutes? [Re: RandomFX]
#19479219 - 01/26/14 10:16 PM (10 years, 11 months ago) |
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Endospores are a bitch, it takes a while to kill them even at high temperature.
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RandomFX
protege


Registered: 12/02/13
Posts: 1,015
Loc: North-East, USA
Last seen: 6 years, 1 month
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Re: Why should you PC s no pour pp5 30 minutes? [Re: Sgt. Pepper]
#19479565 - 01/26/14 11:34 PM (10 years, 11 months ago) |
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ah, thank you for that...just learned some new stuff, and ya I guess they can be some tough SOB's. I had no idea....I cook a lot and am used to at the most cooking something until it is like 180 F...but now I know better:
"An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum.[1] The name "endospore" is suggestive of a spore or seed-like form (endo means within), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is usually triggered by a lack of nutrients, and usually occurs in Gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall. One side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries. Revival of spores millions of years old has been claimed.[2] When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state. Most types of bacteria cannot change to the endospore form. Examples of bacteria that can form endospores include Bacillus and Clostridium.[3] "The endospore consists of the bacterium's DNA and part of its cytoplasm, surrounded by a very tough outer coating. Endospores can survive without nutrients. They are resistant to ultraviolet radiation, desiccation, high temperature, extreme freezing and chemical disinfectants. According to scientist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth - and we know they're very hardened to radiation."[4] Common anti-bacterial agents that work by destroying vegetative cell walls do not affect endospores. Endospores are commonly found in soil and water, where they may survive for long periods of time. A variety of different microorganisms form "spores" or "cysts," but the endospores of low G+C Gram-positive bacteria are by far the most resistant to harsh conditions.[5]
http://en.wikipedia.org/wiki/Endospore
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