Abstract
A self-suppression mechanism of biofilm development in the cyanobacterium Synechococcus elongatus PCC 7942 was recently reported. These studies required quantification of biofilms formed by mutants impaired in the biofilm-inhibitory process. Here we describe in detail the use of chlorophyll measurements as a proxy for biomass accumulation in sessile and planktonic cells of biofilm-forming strains. These measurements allow quantification of the total biomass as estimated by chlorophyll level and representation of the extent of biofilm formation by depicting the relative fraction of chlorophyll in planktonic cells.