Increased Degradative Enzyme Production by Dental Plaque Bacteria in Mucin-limited Continuous Culture

Abstract

Complex communities of dental plaque bacteria were grown under a variety of continuous culture conditions including one in which hog gastric mucin constituted the principal carbon and nitrogen sources. Washed cells and culture supernatants were assayed for fifteen exoglycosidase activities and for the ability to hydrolyse eleven synthetic peptidase substrates. Under all conditions, cultures elaborated a wide range of exoglycosidases and several peptidase activities that were principally cell-associated. Highest exoglycosidase activities were obtained with cultures growing under conditions in which hog gastric mucin constituted the principal carbon and nitrogen sources. Under these conditions, the principal species isolated were Bacteroides spp. and there was extensive utilisation of protein and carbohydrate moieties of the hog gastric mucin. These data support the hypothesis that supra-gingival plaque bacteria are able in vivo to obtain their nutritional requirements from salivary glycoproteins.