KOH string test or Gregersen's Method of determining gram reaction - (Aug/14/2006 )
Hi guys...It's me again with the same question. I really, really need information about this. Any information is very much welcome. Please, please help me.
Can somebody please explain to me what's the principle behind Gregersen's Method or KOH String test? I am supposed to discuss this in class but I have no idea what to tell them except that it is used for differentiating between gram-postive and gram-negative bacteria.I know the procedures, the materials and the expected results of the method but that's all.
Here are my questions about the method:
1)What's the purpose of 3%KOH? Why use 3% and not other concentration?
2)What is the slimy substance produced if the specimen is a gram-negative bacteria?
3)Why only in gram-negative bacteria?
Thank you very much
Can somebody please explain to me what's the principle behind Gregersen's Method or KOH String test? I am supposed to discuss this in class but I have no idea what to tell them except that it is used for differentiating between gram-postive and gram-negative bacteria.I know the procedures, the materials and the expected results of the method but that's all.
Here are my questions about the method:
1)What's the purpose of 3%KOH? Why use 3% and not other concentration?
2)What is the slimy substance produced if the specimen is a gram-negative bacteria?
3)Why only in gram-negative bacteria?
Thank you very much
One of the differences between G+ and G- bacteria is that G+ have much thicker cell walls than G-.
The thick cell wall resist break up by KOH.
Lack of thick cell wall makes G- bacteria to burst if exposed to KOH (or other destroying condition).
When bacteria burst, their content comes out.
DNA is a large part of the content of most bacteria.
DNA is very long, sticky strings.
Why 3 %: because that's what is sold over the counter, I guess.