The Bactericidal Substance Produced by Actinomyces viscosus against Porphyromonas gingivalis

Abstract

The qualitative composition of the microorganisms in the periodontal pocket changes with the progression of periodontal disease. Actinomyces viscosus is involved in the etiology of human gingivitis but not periodontitis. Porphyromonas gingivalis is considered to be a periodontal pathogen. Two bacterial species may interact with each other at the stage of transition from gingivitis to periodontitis. The purpose of this study was to investigate the antibacterial substance against P. gingivalis produced by A. viscosus. In cross inhibition tests, A. viscosus greatly inhibited the growth of P. gingivalis. An antibacterial substance was then extracted from the medium in which A. viscosus T14AV had been cultured anaerobically. The material was purified by ammonium sulfate precipitation, anion exchange chromatography on DEAE sepharose CL-6 B, hydrophobic interaction chromatography on phenyl sepharose CL-4 B and reverse phase high performance liquid chromatography. The activity of the material was evaluated by the diffusion method with P. gingivalis 381 as the indicator strain. Specific activity increased 378-fold with a 26% yield. The material had a molecular weight of 58 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis and had a bactericidal effect on the indicator strain. The activity was lost by trypsin or heat treatment at 90.. for 5 min, but not by endo-a-N-acetylgalactosaminidase, neuraminidase, O-glycanase and N-glycanase. These findings suggest that A. viscosus produces the antibacterial substance against P. gingivalis.