Thiol‐dependent collagenolytic activity in culture media of Bacteroides gingivalis

Abstract

Twenty strains of anaerobic bacteria including some oral species from Bacteroides, Eikenella, Fusobacterium, Capnocytophaga , and Actinobacillus were used for the detection of collagenolytic activity in their culture media (supernatants). Organisms were essentially grown in complete anaerobic basal broth, and collagenolytic activities in the culture media were measured using 14 C‐acetylated soluble collagen from rat skin. When the enzyme reaction was carried out in the standard reaction mixture for 60 min, very low collagenolytic activities were found in culture media of Bacteroides gingivalis 381, 1021, Bacteroides intermedius 163, K l–8, Bacteroides asaccharolyticus ATCC 27067, and Fusobacterium nucleatum ATCC 25586. However, the activity in the media of all species of B. gingivalis tested was enormously enhanced by the addition of reducing reagents having thiol‐groups such as dithiothreitol, L‐cysteine, etc. This stimulated activity was nearly completely inhibited by some thiol‐blocking reagents. In contrast, these reagents had no effect on the collagenolytic activity in the media of the other anaerobes and in the collagenase preparation of Clostridium histolyticum . These results suggest that B. gingivalis produces thiol‐dependent collagenolytic enzyme which may play an important role in the degradation of collagen fibrils in a reduced environment like the deep gingival pocket.