Effects of Mucin, Haemoglobin and Collagen on the Maximum Specific Growth Rate, Biomass and Hydrolytic Enzyme Production ofPorphyromonas gingivalisin Continuous Culture

Abstract

The growth of Porphyromonas gingivalis was studied in continuous culture with proteins (mucin, haemoglobin and collagen) as limiting substrates. The results show that hydrolytic enzymes are produced by the organism at a rate which is sufficient to support rapid growth (μ = 0.13–0.34/h) and high yield (0.14–0.29 g dry weight/1) of cells. The activities of four hydrolytic enzymes (trypsin-like protease, alkaline phosphatase, N-acetyl-β-glucosaminidase and glycylprolyl dipeptidase) varied with the substrates provided. Only the trypsin-like protease appeared in substantial quantities in the extracellular fluid, in the presence of all three proteins, while extracellular glycylprolyl dipeptidase was only produced in the presence of collagen. The data supports the hypothesis that P. gingivalis has the capacity to regulate the synthesis and secretion of hydrolytic enzymes in response to environmental conditions. This may be of considerable importance in the development of periodontal disease caused by P. gingivalis.