Fig 1.
Growth in the liquid and solid media.
(A) Turbidities (OD600) of the original (OG) and mutant (MT) strains in the broth were monitored at 37°C under the anaerobic conditions. Each symbol shows the mean in quadruplicate. Note that the standard deviations are almost hidden by symbols. (B) A typical colonies of the OG and MT strains on the medium solidified with 3% agar. They were inoculated on the surface of the solid medium, and incubated at 37°C under the anaerobic conditions for a week.
Fig 2.
The original (OG) and mutant (MT) strains were inoculated on the surface of the medium containing 0.5% agar and incubated for five days at 37°C under the anaerobic conditions. A typical result is shown in panel A. This experiment was performed three times in different cultures, each in quadruplicate, and the mean and SD are shown in panel B. *Statistically significant difference between the strains (P < 0.01).
Table 1.
Motility of the original (OG) and mutant (MT) strains under the phase-contrast microscopic observation.
Table 2.
Bacterial cell length (μm) of the original (OG) and mutant (MT) strains.
Fig 3.
Association of the original (OG) and mutant (MT) strains with gingival epithelial cells.
The strains (multiplicity of infection of 100) were incubated with confluent Ca9-22 cells for 0.5, 1, 2, and 3 h under anaerobic conditions, and then visualized by fluorescent staining. A representative image of T. denticola (green) associating with Ca9-22 cells (red) at 3 h post-inoculation is shown in panel A. T. denticola cells associating with the epithelial cells were counted in a visual field of 16,900 μm2, and the numbers were expressed as the means ± SD in panel B. This experiment, with 30 images counted for each strain, was performed three times independently. *Statistically significant difference between the strains (P < 0.01).
Table 3.
Chymotrypsin-like protease activity (/μM/cm/cell) of the original (OG) and mutant (MT) strains.
Fig 4.
SDS-PAGE and mass spectrometry analyses.
Bacterial lysates (50 μg) of the original (OG) and mutant (MT) strains were subjected to an SDS-PAGE analysis, followed by CBB staining. A major band (arrowhead), which is clearly detected in MT, was identified as the TDE_1072 protein by mass spectrometry. Molecular-weight standards (kDa) are shown on the left.
Table 4.
Genes with significantly different transcriptional activity between the original and mutant strains.