Comparison of biofilm formation, autoaggregation, hemagglutination and invasion assay.

<p><b>A.</b> Biofilm formation of ATCC 33277, FLL476 and FLL476C’ were compared. Biofilm assay was done by staining adherent cells of overnight cultures grown in microtiter plates with 0.5% (w/v) crystal violet. Blank contained only media. Biofilm forming ability corresponded to OD₅₉₅. <b>B.</b> Autoaggregation of 33277, FLL476 and FLL476C’ corresponded to change in OD₆₀₀ monitored for about three hours after cells were washed and suspended in PBS. A representative sample is shown. <b>C.</b> Hemagglutination activities of ATCC 33277, FLL476 and FLL476C’ were assessed by serially diluting cells in PBS and incubating with sheep RBCs for 3 h at 4°C. Dilutions are listed above and last dilution showing matt formation was taken as the titer. The blank contained only media. <b>D.</b> Antibiotic Protection Assay was used to quantify invasion. <i>P. gingivalis</i> cells that were able to invade HeLa cell monolayers were released by lysis and cultured on BA plates. Infectivity was taken as the percentage of cells recovered. (* = p<0.05).