will a 1W 445 steralize ?

[iFoSh]

Nonsense. "This short-wave ultraviolet light disrupts DNA base pairing causing thymine-thymine dimers leading to death of bacteria"

Think about it: homicide - suicide - genocide - germicide.

:crackup:

Sorry but every time I see Wikipedia sited as a source it makes me laugh...it is the least valued source on the planet when it comes to science. Yes it does cause thymine-thymine dimers which LEADS do the death of the bacteria. BUT it doesn't KILL the bacteria. It prevents them from replicating and producing the structural units needed for survival.

A way to look at it would be that the bacteria are "paralyzed" and "starve" to death.

Edit: Arayan, how did you test to see if there was bacteria before and after??

 

[Arayan]

Arayan, how did you test to see if there was bacteria before and after??

I test it with a pure coulture of Enterobacter aerogenes using a green laser of the same power as control and also on various stock of eukaryotic microorganisms.

 

[iFoSh]

I test it with a pure coulture of Enterobacter aerogenes using a green laser of the same power as control and also on various stock of eukaryotic microorganisms.

Ok cool. The only thing that would do any killing would be the heat, not the light, so 100mW just isn't enough...I say you try 1W+ :eg:

Edit: You would want to be careful though...the bacteria may pop with that much heat at once if you put it directly on the colony and spread it everywhere...

 

[Arayan]

Don't worry Enterobacter is very sensitive to temperature and die at 37 °C

 

[Benm]

The faith of the bacteria depends on the dose of light, obviously.

At lower levels its possible to get a couple of permanent bonds between the dna strands or mutate a couple of bases such that the bacterium cannot replicate it genome anymore, but it still can synthesize most of the proteins it needs to live. It will also still have any of its proteins translated before the exposure, so its possible to remain functional for quit a while, but unable to divide.

Higher levels of exposure will do dna damage to such an extent virtually no new protein can be synthesized, causing the death of the bacterium after some time. Even higher levels will damage even the existing protein, but at that point you're quite litterally at the intensity that would scramble an egg.

For most applications 'unable to divide' is plenty - one single bacterium is rarely a problem, those only start when they are able to divide and grow colonies in your experiments (or dinner).

 

[Cyparagon]

A way to look at it would be that the bacteria are "paralyzed" and "starve" to death.

Are they dead, or are they dead?

If you wanted to be an ass about it, you could also say that snake venom doesn't kill you, it just paralyzes you and your lungs are no longer able to function. Therefore oxygen can't be transferred to vital tissue and the tissues die.

 

[iFoSh]

I wasn't trying to be an ass...it is actually important to understand it if you work with bacteria. If someone asks if you can steralize they need to be aware that the bacterial toxins can still be harmful.

Edit: I'm honestly sorry if you took it as me being an ass. I was just trying to clarify

 

[Arayan]

Are they dead, or are they dead?

If you wanted to be an ass about it, you could also say that snake venom doesn't kill you, it just paralyzes you and your lungs are no longer able to function. Therefore oxygen can't be transferred to vital tissue and the tissues die.

You're describing a physiological process that began with the paralysis and ends with death. While, I believe, he was talking about a different thing... when you perform a cell count is necessary to distinguish the paralyzed cells in respect to the not-viable cells at a fixed time.