Which conditions promote QS in Pseudomonas aeruginosa?

[greenbear]

Hi everybody,

As most of you who had experience with Pseudomonas aeruginosa know, P.a. produce two major types of AHLs: 3-oxo-C12-HSL, and C4-HSL. However, I wonder whether the bacteria would secrete these AHLs while growing as planktonic cells in LB broth (or any other kind of broth)? All that I know is that at higher cell density, bacteria produce more AHLs. But I have no idea whether this refers to bacteria growing on some kind of surface (so that they can develop biofilm at the same time).
Our future experiment requires mixing Pseudomonas with E.coli in liquid medium (such as LB broth) for QS testing. And it's necessary that Pseudomonas must produce AHLs. However, our preliminary exp seemed to show that very little AHLs were produced, if at all. I guess there must be a relation between cell density and AHL concentration, but not sure exactly.
Any suggestion on what is the optimal conditions (like OD600..) for P.a. to produce AHLs?

Any help would be appreciated!

G_B

[mkwaje]

Hi...we studied quorum sensing once. It was interesting but we didn't get to experiment on it. Here is an article about QS in Pseudomonas. Maybe you can find something useful in there.

http://jb.asm.org/cgi/content/full/188/9/3169

In some cases like S. aureus, you have to reach a certain density (like 10^8 cells) for it to produce toxin. I just don't know the optimum density needed for P.a.

good luck.