A comparison of fibronectinolytic activities from several oral bacteria.

Fibronectinolytic activity from two Gram-positive microorganisms (Streptococcus mutans and Bacterionema matruchotii), and from three Gram-negative oral bacteria (Bacteroides intermedius, Bacteroides gingivalis and Haemophilus actinomycetemcomitans) were compared. 125I-labelled human plasma fibronectin (FN) was incubated either either with bacterial extracts or with concentrated culture medium samples and the patterns of FN-degradation products were determined by SDS-PAGE. Results to date have shown that Streptococcus mutans, Bacterionema matruchotii and Haemophilus actinomycetemcomitans were unable to degrade FN. On the other hand the Gram-negative Bacteroides intermedius and Bacteroides gingivalis were shown to contain Fn-degrading activity. The highest activity was found in the bacterial extracts of Bacteroides gingivalis. Inhibition assays demonstrated that fibronectinolytic activity of Bacteroides gingivalis occurred predominantly by cysteine proteinase(s) while that of Bacteroides intermedius by a common action of serine and cysteine proteinases.