Killing bacteria

[iwra]

I got some questions about common bacteria found around the house and fluid transfer.

 

1. What temperatures would bacteria die through heat? And what temperature would it die through cold? If it even dies from freezing, or would it revive after it defrosts?

 

2. I read that bacteria can't survive in things like honey, because the glucose content is so high. But can bacteria survive in or on salt? Lets say I licked a spoon, and just left it there in the table overnight. Assuming the bacteria is live and multiplying, then in the morning, shoved the spoon into a container filled with salt. Come back to check it later, would the bacteria live or die?

[herpguy]

I suppose it depends on the species...right?

[iwra]

If I asked the questions regarding bacteria living in the depths of the Artic ocean and one on the sink, obviously, there is some huge difference at what temperature it will die.

 

I am not asking for any specific species. It clearly states "common bacteria found around the house and fluid transfer" (mainly saliva).

[herpguy]

I repeat, I suppose it depends in the species. There is more than one type of bacteria found around the house and such. I will stay out of this thread for now. I was just trying to make a point...

[iwra]

Again, that was obvious. If I asked how much sodium does one need. Of course, it will depend on diet, genetics, and such. What point is there to make? That there is a difference between species of bacteria!? Like I needed 2 indirect replies to tell me that...

 

I am fully aware there is more than one type of bacteria around the house. Would else would I say "common bacteria"!? 1 bacterium, 2+ bacteria.

 

I am not asking for any rare or super bacteria around the house or in saliva. It clearly states "common". Even if I stated something very specific, I highly doubt it that anyone here is able to provide a detailed explaination. But that is not what I am asking for.

[ydoaPs]

Again, that was obvious. If I asked how much sodium does one need. Of course, it will depend on diet, genetics, and such. What point is there to make? That there is a difference between species of bacteria!? Like I needed 2 indirect replies to tell me that...

if it is a non-specified species, how can you answer? take, heat tolerance for example. some can live in permafrost, and some live in geisers.

 

 

I am fully aware there is more than one type of bacteria around the house. Would else would I say "common bacteria"!? 1 bacterium, 2+ bacteria.

it really depends on which species.

 

I am not asking for any rare or super bacteria around the house or in saliva. It clearly states "common". Even if I stated something very specific, I highly doubt it that anyone here is able to provide a detailed explaination. But that is not what I am asking for.

it depends on what the "common bacteria" are.

[Steph]

it doesn't depend that much on the species. be realistic. of course thermophiles will survive in higher temperatures, but how many termophiles can you find in your kitchen?

 

I don't have a precise answer to your question but autoclaves running at 121 oC and high pressure get rid of most bacteria, including most Bacillus and Clostridium species (of course there are exceptions). About the salt thing, I can't say i've tried that, but it should be like human cells, albeit at higher concentrations. however, salt is much more abundant on earth than 121oC areas, so you'd have more species evolved to survive in water with high salt concentration. I also know a lot of bacteria can survive in temperatures up to 55oC (melting temp of agar). about cold temps, I have no idea. I would think freezing temp (or a little below that) would damage most cells. I know some species evolved to counter that though.

 

Sorry I can't be more precise... but I think you could find tables in the internet as to how high a temp a specific species of bacteria will survive.

[thief75]

If you are worried about contamination or just "good housekeeping" 10% Bleach is what you need.

 

As far as bacteria growths it is very difficult to predict. I have seen very clean labs have the roughest time getting rid of persitent bacteria contamination but on the otherhand I have seen dirty labs never have a problem.

 

But no I would not lick the spoon.

[Mindtaker]

I just want to add my $0.02 in. It can take quite a bit of heat at normal atmospheric pressure to kill normal household bacteria. The best way to kill bacteria with heat at home is probably a pressure cooker. I'm uncertain at a specific response to cold temps. since some bacteria will just go dormant and not actually die.

 

Many bacteria can survive a high salt content enviroment. That would really depend on the specific bacteria. However, in general most bacteria will probably have to struggle to surive on a 100% salty enviroment. Althought the biggest problem would be that the bacteria need water. To test this you'll want to soak the spoon overnight in a salty, aqueous place.

[ecoli]

that's unecesarily complicated, Mindtaker. just use ethanol.

[Immunologist]

First, the case of cold:

 

Gram positive bacterias have a solid cell wall and will survive freezing (down to 0 Kelvin if you suceed to it), but will obviously not proliferate if there is no liquid water. Once thawed though, enough of them will have suvived to start to grow again. Gram neg don't have the same cell wall and will resist freezing less easily.

 

Second the case of warmth:

 

Pasteurisation (killing most of pathogens) is done in milk by heating at 75 degs for 30-45 secs. Therefore this ia a part of answer. However, to kill Bacillus stearothermophilus, one must reach 121 degs and high pressure to kill the spores, and this during 20 minutes.

 

For the salt:

 

Cells will not live if water availability (Wa) is too low. When increasing salt concentration, you reduce the disponibility of water. This the same for sugar. But, as bacterias have cell walls, they won't lyse, they will remain dormant (and might die, but not for sure). This is the same phenomenon for sugar.

This means that nothing "grows" in your jam, but if you dilute it in water, it could!

 

See ya!

[Dak]

it doesn't depend that much on the species. be realistic. of course thermophiles will survive in higher temperatures, but how many termophiles can you find in your kitchen?

 

I know it's not a thermophil, but cant the bacteria found on rice -- B.Seriae or something like that -- survive boiling? hence why you shouldnt re-heat rice, 'cos after exposure to the water the rice-bugs reactivate, and if rice is boiled and then left around for hours, the toxins will build up and then you'll get ill, even if you reheat the rice?

 

hmm... come to think of it, i think they might be bacterial spores actually...