LPS-binding antibiotic polymyxin B?

Question

Dear Sir/Madam,

I would be really grateful if you could explain me, what's LPS-binding antibiotic polymyxin B and how it is used while studying the bacterial cells.

Yours faithfully,

Kristina

Answer 1

I'm not exactly sure, but simply judging from the name, it's an antibiotic that binds to LPS (lipopolysaccharide), one of the components in the membrane of Gram-negative bacteria.  

According to wikipedia, it is used to alter the chemical structure of the LPS membrane and makes it more permeable to water.  The uptake in water kills the Gram-negative cells, but does not kill Gram-positive cells because Gram+ cells have no LPS in their plasma membrane.

I suppose it could be used to separate Gram+ and Gram- bacteria from each other (since it kills Gram- bacteria and not Gram+).  It can also be used to lyse Gram- bacteria.

http://en.wikipedia.org/wiki/Polymyxin_b

This might help too.