This is an interesting article that raises the possibility that increased mutations lead to microcoloney formation in P. aeruginosa biofilms. The results are quite interesting and they open up lines of further inquiry.

A big question in my mind relates to pre-existing versuses microcolony induced mutations. Perhaps the cell that gives rise to the microcolony already acquired several mutations that allowed for GFP fluroesence observation and microcolony formation during planktonic growth.

Perhaps a stronger promoter and a brighter flurorescent protein variant (mCherry maybe) would allow the visualization of the chromosomal experiments. I also wonder if planktonic cells were subjected to FACS analysis if a few GFP expressing cells would be found. That might address the pre-existing versus microcolony induced mutation.

It's a nice experimental set up that should be useful for other biofilm researchers.