DNA staining of the pneumococcal EPS matrix and disruption with DNase. Fig. 4A. Biofilms stained with PicoGreen, a dsDNA stain, and Syto 59 shows that S. pneumoniae biofilms treated with 1000 μg ml-1 Pulmozyme (+) were substantially reduced compared to untreated biofilms (-) in both high and low BFI strains. Scale bar = 30 μm. Figure 4B. Quantification of reduction in biofilm volume (total biomass) measured by COMSTAT upon treatment with different concentrations of Pulmozyme: Untreated controls □; 1 μg ml-1 Pulmozyme ▩; 100 μg ml-1 Pulmozyme ⊟; 1000 μg ml-1 Pulmozyme ■. Bars show average of PicoGreen signal, which stains extracellular dsDNA, and Syto59, which stains intracellular nucleic acid. (Error bars represent standard error of the mean; n = 10; 5 randomly chosen microscopic fields from duplicate experiments. *Significantly different from untreated controls (P values < 0.05); ** (P values < 0.01). Statistical comparisons were made using one-way analysis of variance (ANOVA) (Excel 2000, Microsoft).