Résumé
Oral infection with Porphyromonas (P.) gingivalis causes periodontitis that is manifested by the destruction of gingival connective tissues. Although a few types of antibiotics are effective against the infection, its use induces the appearance of drug-resistant bacteria. The present study shows that the fermented product of Aspergillus (A.) oryzae S-03, cultivated on the fat-removed soybean, inhibits the cell growth of the P. gingivalis. Likewise, the fermented product of the S-03 strain cultured for 26~42 h displays an inhibitory activity to gingipain as a virulence factor of P. gingivalis. The activity is not lost even with heat treatment at 100degrees C for 15 min. We also demonstrate that the S-03 strain exhibits high protease activity. In addition, the strain does not produce aflatoxin because of the loss of a regulatory gene, aflR, necessary for the toxin biosynthesis.