FIG. 2.

Phenotypes of wild-type A. actinomycetemcomitans strain IDH781N and pgaC mutant JK1048. (A) Surface attachment was measured in 96-well microtiter plates by staining with crystal violet. The optical density (O.D.) at 590 nm is proportional to the number of attached cells in the well. Strain JK1047 contains a transposon insertion in flp-1 which results in a complete loss of pilus production and surface attachment (16). The values indicate means (± standard deviations) for triplicate wells. (B) Detachment of preformed biofilms by proteinase K and sodium metaperiodate as measured by crystal violet staining. The values indicate means (plus standard deviations) for triplicate wells. The asterisks indicate values that were significantly less than the those of corresponding mock-treated control (P < 0.05; unpaired two-tailed Student t test). +, present; −, absent. (C) Autoaggregation of IDH781N and JK1048 (left) and of JK1048 carrying the vector plasmid pJAK16 or the complementary plasmid pVK82 (right). (D) Colonies of strains IDH781N and JK1048 and of strain JK1048 carrying the vector plasmid pJAK16 or the complementary plasmid pVK82 on Congo red agar. The dark colonies were red, and the light colonies were white. The colonies were ∼3 mm in diameter.