Comparison of four methods for quantification of biofilms in biphasic cultures

Three methods for determining the total biofilm amount in biphasic cultures have been compared: dry weight by filtration after solvent treatment, opti cal density with a biomass probe and protein content. The activity of the b iofilm was estimated through mineral nitrogen consumption. Calculation of t he coefficients of variation shows that these parameters could be used to c haracterise such a biofilm. The optical density by biomass probe was the mo st reliable one (repeatability <0.5%) to quantify total biofilm and a linea r relation was verified against dry weight.