Teeka et al. used this
method to screen the potential PHA producing bacteria from
soil, and Ramachandran and Abdullah also observed
the colonies formed on nutrient rich medium under ultraviolet
light (UV) to screen for the pink fluorescence which
indicated the presence of PHA producers. Kitamura and
Doi first demonstrated this viable colony method on
agar plates; they induced the isolates to accumulate PHA by
culturing in E2 medium containing 2% (w/v) glucose before
Nile blue A staining. The PHA accumulating colonies, after
Nile blue A staining, showed bright orange fluorescence on
irradiation with UV-light and their fluorescence intensity
increased with increase in PHAcontent of the bacterial cells.