FIG 4.

The function of the polysaccharide synthase genes in biofilm formation in TSBr. (A) The amount of biofilm formed by the deletion mutants of the gene encoding polysaccharide synthase in TSBr. (B) CLSM analysis of the biofilm formed in TSBr. The cells in the biofilm were stained with the LIVE/DEAD BacLight bacterial viability kit for 30 min. Representative images from three independent experiments are presented. (C) An aggregation assay of the bacterial cells. The roles of eDNA and fructan in cell aggregation were examined by mimicking the extracellular matrix synthesized in TSBr. Five micrograms per milliliter genomic DNA of UA159 and/or 250 μg/ml commercial inulin was added to 3 ml of cell suspension, which was grown in BHI and adjusted to an OD₆₀₀ of 1.5 with aggregation buffer. The data are presented as the means ± SD of the results from three independent experiments. The asterisks indicate a significant difference between two groups (Student's t test, P < 0.05).