FIG. 4.

Analysis of biofilm formation of wild-type X. fastidiosa A05 and gacA mutant DAC1984 by a crystal violet staining method (29). Biofilm cells were stained with crystal violet, the amount of stain was dissolved with ethanol, and the resulting absorbance was measured at OD₆₅₀. Three replicates were used in each experiment. For each assay time, different letters indicate significant differences (Student's t test; P < 0.05) between the wild type and the mutant.