Abstract
The purpose of this study was to investigate the phenotypic characteristics and coaggregation properties of Actinomyces odontolyticus strains isolated from periodontal pockets of adult periodontitis patients. Wild strains of A. odontolyticus were isolated and identified by their morphological and biochemical features. Their prevalence was 52.5%, and accounted for up to 9.3% of cultivable microbiota. A. odontolyticus seemed to comprise a larger component of the subgingival microflora in 3 to 5 mm deep pockets than in deeper ones. Seven of the twenty-one strains formed large colonies over 2 to 3 mm in diameter on blood agar plates. As for biochemical tests, 90.5% of isolates hydrolyzed esculin, 61.9% starch, and 85.7% produced acid from xylose. These are relatively high positive percentages, especially esculin hydrolysis, compared with other reports dealing with strains isolated from other than periodontal pockets or type strains.
Coaggregation properties of A. odontolyticus with Porphyromonas gingivalis were also investigated. It was not inhibited by lactose. Coaggregation molecule (s) on A. odontolyticus resisted heat, trypsin, pronase E and periodate. On the other hand, complementary molecule (s) on P. gingivalis resisted trypsin and pronase E but showed heat and periodate lability. N-acetylneuraminic acid (NANA) completely inhibited the coaggregation, as did treatment of P. gingivalis cells with neuraminidase. Cysteine, arginine, and glutamic acid were also effective inhibitors. It was suggested that coaggregation molecule (s) on A. odontolyticus recognize the NANA residue on P. gingivalis. Cysteine, arginine, and glutamic acid might be implicated in the epitopes of coaggregation molecule (s). Bacterial cell hydrophobicity influenced coaggregation.
