Fibrinolytic activity of oral anaerobic bacteria.

We assayed 13 species of anaerobic microorganisms found in the human oral cavity for fibrinolytic activity. Activity was detected in 6 of 6 strains of Bacteroides melaninogenicus subsp. asaccharolyticus, 3 of 3 strains of Bacteroides oralis, and 11 of 12 strains of Treponema denticola. The activity observed in Bact. oralis was variable and was the only species that required plasminogen. The fibrinolytic activity of T. denticola was extracellular. The culture supernatant was concentrated by ultrafiltration, fractionated with ammonium sulphate, then applied to a column of 2 per cent agarose. This resulted in a 1750-fold purification. The purified T. denticola fibrinolysin had only one major band on polyacrylamide gel electrophoresis, and an apparent molecular weight near 1,000,000. It was not inactivated by heating at 75 °C for 10 min and was stable from pH 5.5 to 9.5. The enzyme appeared to be an aggregation of smaller molecules. The fibrinolytic enzyme of Bact. melaninogenicus subsp. asacch. was bound to the cell membrane and shared many properties with the collagenase reported by others. The activity of this enzyme was enhanced by treatment with SDS.