Accessory pigment fluorescence for quantitation of photosynthetic microbial populations.

The in vivo fluorescence of the primary accessory pigments in purple bacteria (carotenoids), green bacteria (bacteriochlorophyll), green algae (chlorophyll), and cyanobacteria (phycocyanin) was found to be a linear function of cell concentration over three of four orders of magnitude. The lowest cell concentrations detectable were 10(4) cells/ml for procaryotes and 10(3) cells/ml for eucaryotes.