Phosphotransfer by Ptk1 is required for P. gingivalis community development with S. gordonii and for extracellular polysaccharide production. A. P. gingivalis 33277, Δptk1 (Dptk1), Δptk1 + pptk1 (CDptk1) and Δptk1 + pptk1 containing a K614M/S615C mutation in the Walker A domain (CMDptk1) were reacted with a substrate of S. gordonii for 18 h. Total biovolumes of P. gingivalis and S. gordonii in a 213 × 213 μm area were obtained with by confocal microscopy, analyzed by Volocity and data are expressed as ratio of P. gingivalis (Pg) to S. gordonii (Sg). B. P. gingivalis strains were stained for extracellular polysaccharide with FITC-labeled concanavalin A and wheat germ agglutinin. Bacterial cells were stained with Syto-17. Fluorescent images were collected by confocal microscopy and the ratio of lectin staining of EPS to whole cell staining determined using Volocity. Error bars are SD, n = 3. ***P < 0.001; ****P < 0.0001, ns P > 0.05.