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can you explain something ?
    #2802631 -


deleted

Edited by baltazar (06/18/04 07:31 AM)

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Re: can you explain something ? [Re: baltazar]
    #2802812 -

raising the pressure raises the boiling point of water, allowing the water to heat above the normal atmospheric boiling temp.

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Re: can you explain something ? [Re: baltazar]
    #2803056 -

Pressurized you can achieve a higher temp...as simple as that


--------------------
So hard to be ....WDWGFH?
Texas is humongus compared to France
Our Gair, who art in Texas,
Paw Paw be thy Name....
My friends are thirsty


You never see a motorcycle parked outside a Psychiatrist office:biker:

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Re: can you explain something ? [Re: OldSpice]
    #2803318 -

deleted

Edited by baltazar (06/18/04 07:32 AM)

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Re: can you explain something ? [Re: baltazar]
    #2803446 -

Yes at 15 psi it raises the boiling point of water to approx 250 degrees


--------------------
So hard to be ....WDWGFH?
Texas is humongus compared to France
Our Gair, who art in Texas,
Paw Paw be thy Name....
My friends are thirsty


You never see a motorcycle parked outside a Psychiatrist office:biker:

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Re: can you explain something ? [Re: baltazar]
    #2803485 -

baltazar said:
and the higher temperature is that that killes the bacteria ? ...




it kills most contaminants, there are some that will not germinate unless they are put through conditions which are destructive to most others... for the purposes of mycology to kills any which would immediately pose a threat to the culture...

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Re: can you explain something ? [Re: baltazar]
    #2803524 -

everyone basically has it right... it is basic chemistry (higher the pressure the higher the temperature). And the pressure cooker works as a mini autoclave raising the pressure inside so the temperature can raise above 100 degress celcius (to 121 degrees C). And at that temperature most things that cause contamination are killed.

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Re: can you explain something ? [Re: baltazar]
    #2803577 -

Okay, here goes.

Proteins, which are the important bits when it comes to living things, denature when they get too hot -- they change shape and no longer function properly. 

Most proteins necessary for life denature somewhere above 100*F and below 212*F.  This is why fevers work to help fight off bacterial and viral infections -- and why excessively high fevers kill. 

Unfortunately for us, many bacteria have special forms made to endure environmental extremes.  Heating up something to 212*F will kill everything except these endospores. 

Fortunately, 212 is pretty close to the design limits for endospores.  So we just need to get things a bit hotter.  Using a pressure cooker effectively increases the atmospheric pressure inside the vessel.  When you increase the atmospheric pressure, the temperature at which water will boil goes up.  So, at 15 lbs pressure, you're filling the pressure cooker with ~250*F steam instead of 212*F steam.  Those temperatures kill endospores dead.

...Wow, that was long.  I must be bored. :wink:


--------------------
"Do we want the stars? We can have them. Can we borrow cups of fire from the sun? We can and must and light the world." --"On the Shoulders of Giants", Ray Bradbury

All of my posts are full of fiction and blatant lies.

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Re: can you explain something ? [Re: Sev]
    #2804214 -

Sev said:
Most proteins necessary for life denature somewhere above 100*F and below 212*F.  This is why fevers work to help fight off bacterial and viral infections -- and why excessively high fevers kill. 


...Wow, that was long.  I must be bored. :wink:



Everything else you said is correct, but not this.  The reason fevers help fight infections is that they speed the body's immune response.  The difference in temperature may throw off the ideal conditions for some pathogens, but extreme temps certainly arn't going to kill bacteria and viruses before they kill a human.

Not trying to dicker or anything, you post good info, I just wanted to see correct info here.

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Re: can you explain something ? [Re: Sev]
    #2804306 -

You have to get into temprature ranges that a PC can't reach to kill endospores.

He he he...I tried to not be boaring again but oh well here goes.

The definition of an endospore is an extremely heat-and chemical-resistant, dormant, thick-walled spore that develops within bacteria. Endospores are extraordinarily resistant to environmental stresses including heat, UV radiation, gamma radiation, chemical disinfectants, and desiccation. Endospores can remain viable for thousands of years or longer. An example of this are some endospores that were found on Dominican bees that had been encased in amber for 25 - 40 million years. These dormant structures can be found in several different types of bacteria: Bacillus, Clostridium, and Sporosarcina. I will be trying to isolate Bacillus in my experiment, and after isolation prove that it is indeed an endospore forming bacterium by getting it to transform into its dormant/ spore state.

Bacillus is a gram-positive aerobe that can be found in soil. It appears as straight rods 0.5 - 2.5 x 1.2 - 10 mm, and is chemoorganotrophic, which means that it gets its energy by oxidizing chemical compounds, and organic molecules are its electron source.

Here are some examples of spore forming bacteria out in the world: Clostridium perfringens and Clostridium botulinum (both anaerobes) are food poisoning microorganisms. C. perfringens commonly occurs in meats that have been heated (O2 depletion) and then slowly cooled. As these are ingested the cells sporulate in the intestine, producing an enterotoxin that causes symptoms of nausea, diarrhea, and abdominal cramps. C. botulinum is found on potatoes that are not heated sufficiently and cause the production of toxins. Bacillus cereus is another spore forming bacterium that also is found on starchy foods like rice. Its symptoms are similar to those of C. perfringens.

Microorganisms are also used in bioterrorism. One such spore forming bacterium is Bacillus anthracis which results in anthrax. This organism's endospores can survive for decades in animal products and soil. It can enter the body through cuts and abrasions (cutaneous anthrax), or by inhaling endospores (pulmonary anthrax). Symptoms resemble that of the flu, and if it invades the bloodstream the disease can be fatal.

Vancomycin is an antibiotic that is bactericidal for some forms of Bacillus and Clostridium, as well as other microorganisms. It works by binding to the D-alanine-D-alanine sequence so the peptide interbridge cannot be formed. This results in the formation of weak peptidoglycan which eventually leads to the cells lysing because of osmotic differences.

Sporulation is the process by which an active vegetative cell turns into its dormant spore state. This occurs because of a lack of nutrients, or because the cell was exposed to environmental stress. There are several steps to the process which are discussed below:
Formation of nuclear filament within the vegetative cell.
Cell membrane folds inward enclosing part of the DNA and forming the septum.
Continuation of the cell membrane to fold inward and engulf the immature spore.
Spore cortex is formed in the space between the two membranes.
A protein coat is developed around the cortex.
The spore continues to mature within the sporangium (mother cell).
Lysis of sporangium and release of spore.

For a spore to go back to its active vegetative cell state, it goes through a process called germination. Amino acids and sugars are two examples of the nutrients that can trigger germination. This involves the spore swelling, either the absorption or rupture of the spore coat, loss of heat/chemical resistance, the release of spore components, and increased metabolic activity. The third stage, outgrowth, follows germination. This involves the synthesis of new components, and emergence from the spore coat ready to develop into an active bacterium.


--------------------
All creatures tremble when faced with violence. All creatures fear death, all love life. If we can only see ourselves in others, then how could we possibly hurt another creature?


:growingweed: Join us at the Growery! :growingweed:

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Re: can you explain something ? [Re: Magash]
    #2804610 -

Magash said:
You have to get into temprature ranges that a PC can't reach to kill endospores.
<snip>
For a spore to go back to its active vegetative cell state, it goes through a process called germination.

<snip>




Nice post Magash.

This is why soaking of grains for a few hours helps against contams, so the endospores germinate and loose their heat resistant armor just in time for a nuking.

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Re: can you explain something ? [Re: psilomonkey]
    #2804649 -


deleted

Edited by baltazar (06/18/04 07:29 AM)

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Re: can you explain something ? [Re: baltazar]
    #2804668 -

baltazar thats an arse theory exploding glass jars and getting splashed with 200degree oil doesnt sound productive. take that extra second and think before making silly suggestions.


Later NoG

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Re: can you explain something ? [Re: NoG]
    #2804701 -

deleted

Edited by baltazar (06/18/04 07:29 AM)

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Re: can you explain something ? [Re: baltazar]
    #2804730 -

Try it, and then let someone who will not be present while you are doing it report it to us.(because YOU WON'T BE ABLE TO ANYMORE!!)

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Re: can you explain something ? [Re: Tantalus]
    #2806823 -

Tantalus said:
Everything else you said is correct, but not this.  The reason fevers help fight infections is that they speed the body's immune response.  The difference in temperature may throw off the ideal conditions for some pathogens, but extreme temps certainly arn't going to kill bacteria and viruses before they kill a human.




Actually, it's still true, but I should've explained more.

High-but-not-lethal temperatures still cause a certain amount of protein denaturing -- the proteins deform and do their jobs less well.  In this case, however, at these relatively low temps, the denaturing generally isn't permanant.

A fever impairs both the host and the pathogen.  However, the point is to arrest or reduce the rate of reproduction of the pathogen so that the body can muster and fight it.  The body pulls a Russian Army on the pathogen, and throws everything at it while keeping the temps up to try and prevent the pathogen from breeding.  The temperatures don't help the body any -- indeed, they cause significant problems for it, which is why you feel like utter shit when you've got a high fever -- but since a (moderately healthy) body has huge reserves to draw on, this is a viable tactic. 

Think about it.  106*F or so kills cube spores and myc.  At 105-106 core temp, a human is risking death or permanant disability.  (And all of this is because key enzyme structures begin to denature at these temperatures, of function so badly that the system breaks down.)  A 103 or 104 fever is very close to that danger zone.  The human body is suffering under that temperature -- it isn't going to respond more quickly.  This is actually key in limiting viral infections, since the body's own machinery is being used to produce more viral particles.  By raising the temperatures and causing its own systems to malfunction, the body helps curb the viral reproduction.

So, yes.  The high (fever) temperatures won't kill bacteria without killing their host, but they inhibit reproduction through the mechanisms I mentioned -- namely, protein denaturing through high temperatures.  :smile:


--------------------
"Do we want the stars? We can have them. Can we borrow cups of fire from the sun? We can and must and light the world." --"On the Shoulders of Giants", Ray Bradbury

All of my posts are full of fiction and blatant lies.

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Re: can you explain something ? [Re: Magash]
    #2806900 -

I've gotta respectfully disagree, Magash.  The temperatures reached in a pressure cooker or an autoclave are sufficient to destroy endospores -- about the only things that might have a chance of survival are deep-sea prokaryotes that live around volcanic vents -- certainly not a common household contam.  :wink:

According to  textbookofbacteriology.net,
a 15# autoclave reaches 121*C (250*F) and should be maintained for 15 minutes to destroy, well, anything.  These figures sound about right, at least by what I remember from when I was more into bio. 

Endospores can survive boiling -- just.  That's close to the extreme limits of their endurance, though.  The main problem with sterilization of certain materials is that they are insulative (like the hulls of seeds) and that you're often preparing a relatively large amount of material.  A quart jar can take a long time to heat up -- I'd wager that any quart of, say, WBS that sprouted something nasty wasn't PC'd long enough for the entire mass of material, including the seed kernels inside of, say, sunflower hulls, to reach the proper temperature for the full 15 minutes.

This is, frankly, why botulism poisoning is so goddamned rare now.  Pressure canning allows for the destruction of the endospores.  Back when a lot more people were doing canning at home, by either boiling or by using lighter-pressure pressure cookers (or just using their PCs improperly,) it was more of a problem.

So long as you give it enough time, the steam generated in a 15lb pressure cooker will destroy anything that you might run into.


--------------------
"Do we want the stars? We can have them. Can we borrow cups of fire from the sun? We can and must and light the world." --"On the Shoulders of Giants", Ray Bradbury

All of my posts are full of fiction and blatant lies.

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