Can decomposition take place in the absence of bacteria?

[Rare_Plant_Guy]

Can decomposition take place in the absence of bacteria?

If sterilized organic material were in a sterile environment (with moisture) would it last forever?

 

[StringJunky]

3 minutes ago, Rare_Plant_Guy said:

Can decomposition take place in the absence of bacteria?

If sterilized organic material were in a sterile environment (with moisture) would it last forever?

 

This is how Pasteur demonstrated the existence of microbes: by heating a broth in apparatus that didn't allow their ingress. I think in time, if there is air,  there will be oxidation and other reactions going on, but it will last longer. To prevent additional reactionsI thinkit  it would need to be dessicated or frozen to somewhere around nitrogen temperature.

[Strange]

Modern packaging methods sterilise food and then pack it in an inert atmosphere (typically nitrogen, I think). This gives a very long shelf life. 

3 hours ago, Rare_Plant_Guy said:

Can decomposition take place in the absence of bacteria?

You would need to eliminate fungi as well.

[StringJunky]

33 minutes ago, Strange said:

Modern packaging methods sterilise food and then pack it in an inert atmosphere (typically nitrogen, I think). This gives a very long shelf life. 

You would need to eliminate fungi as well.

For spores I think it would need heating under pressure.

[Strange]

Just now, StringJunky said:

For spores I think it would need heating under pressure.

I think radiation is used as well. Where it won't damage the thing being processed.

[StringJunky]

1 minute ago, Strange said:

I think radiation is used as well. Where it won't damage the thing being processed.

Yes, that option is there as well.

[CharonY]

14 minutes ago, StringJunky said:

For spores I think it would need heating under pressure.

Spores (esp. bacterial) survive autoclaving quite well (as well as UV radiation).

[StringJunky]

15 minutes ago, CharonY said:

Spores (esp. bacterial) survive autoclaving quite well (as well as UV radiation).

I thought  127C at whatever pressure sorted them out, except prions.

Quote

In a dry air oven, it takes two hours at 160°C to kill spores of the bacterium Clostridium botulinium (associated with canned food). Using saturated steam, the same spores are killed in just five minutes at 121°C, proving that moist heat is more effective than dry heat.  https://www.eurotherm.com/sterilization

 

Edited April 20, 2018 by StringJunky

[CharonY]

15 minutes ago, StringJunky said:

I thought  127C at whatever pressure sorted them out, except prions.

 

It depends on the bacterium (and even strain), buffer composition and a few other factors. Luckily clostridia are decently killable for the most part, but especially thermophiles can survive multiple autoclaving attempts (yupp, tried that). But even in more common bacteria such as Bacillus you can find that occasionally spores survive and mess up experiments.

[StringJunky]

8 minutes ago, CharonY said:

It depends on the bacterium (and even strain), buffer composition and a few other factors. Luckily clostridia are decently killable for the most part, but especially thermophiles can survive multiple autoclaving attempts (yupp, tried that). But even in more common bacteria such as Bacillus you can find that occasionally spores survive and mess up experiments.

So, they are pretty tough then.

[CharonY]

Some of them, yes. That being said, autoclaves are routinely tested with spore standards (usually heat tolerant Geobacillus and Bacillus) and under controlled conditions they do die fairly effectively. But if you have complex media (e.g. environemental samples) or some of the hardier bastards in them, it can be challenging, mostly as a single germinating spore can mess up things (especially for long-term experiments). Realized that I said that spores survive quite well. Should read "some spores".

[John Cuthber]

In principle, most proteins are unstable in the presence of water, they hydrolyse to the corresponding amino acids.

That process is slow, but it happens without microorganisms.

Fats go rancid without help from bugs.
Even if sterile filtered, wine matures which, from a different point of view, is a decomposition (of the stuff you don't like).

Chemistry carries on unless you get the stuff to absolute zero (which you can't).

[dimreepr]

1 minute ago, John Cuthber said:

In principle, most proteins are unstable in the presence of water, they hydrolyse to the corresponding amino acids.

That process is slow, but it happens without microorganisms.

Fats go rancid without help from bugs.
Even if sterile filtered, wine matures which, from a different point of view, is a decomposition (of the stuff you don't like).

Chemistry carries on unless you get the stuff to absolute zero (which you can't).

What about desiccation?

[John Cuthber]

12 minutes ago, dimreepr said:

What about desiccation?

It's  possible in some cases, but severe drying denatures proteins too, so that's a sort of decomposition.

Essentially, this thread is saying "What can we do about the 2nd law of thermodynamics?", and the answer is "Not a lot".

Edited April 20, 2018 by John Cuthber

[dimreepr]

1 minute ago, John Cuthber said:

It's  possible in some cases, but severe drying denatures proteins too, so that's a sort of decomposition.

Essentially, this thread is saying "what can we do about the 2nd law of thermodynamics, and the answer is "not a lot".

Indeed, nothing lasts forever.

[Rare_Plant_Guy]

Very interesting information. I am impressed at the level of knowledge here!

Perhaps a few things I wish I had NOT learned (Autoclave doesn't kill everything? I'm never getting surgery or going to the doctor again!)

Thanks to all for the replies.

[CharonY]

On 4/20/2018 at 9:44 PM, Rare_Plant_Guy said:

Very interesting information. I am impressed at the level of knowledge here!

Perhaps a few things I wish I had NOT learned (Autoclave doesn't kill everything? I'm never getting surgery or going to the doctor again!)

Thanks to all for the replies.

Well, that should not be the lesson from it. Almost all pathogens (that I can think of) are reasonably well killed by autoclaving.