Re: DRAQ5 staining of bacterial cells

Dongjuan DAI wrote:

>
> Have you ever used this dye, DRAQ5 from Biostatus, on bacteria? I
> tried it on both E.coli K12 and Pseudomonas aeruginosa. But I cannot
> get any bacterial cells stained. Do you have any ideas why I fail? I
> tried from 1ug/ml to 20ug/ml of DRAQ5.

I have not used DRAQ5 on bacteria, but others have. The dye does not  
increase fluorescence by a large amount when bound to DNA, so you  
would expect more problems with background fluorescence than you  
would see with other dyes. Also, if the dye is relatively  
hydrophobic, you may have to permeabilize the outer membranes of Gram- 
negative organisms with something like EDTA to get the dye in. The  
outer membrane is really more of a cell wall than a membrane, so you  
don't necessarily kill cells by permeabilizing it, although you do  
change their transport characteristics.

Why, in particular, do you want to use DRAQ5?

-Howard