Reducing medium for the cultivation of Porphyromonas gingivalis

Porphyromonas gingivalis, a micro-organism frequently associated with human periodontal diseases, is commonly cultured under a reducing atmosphere in enclosed cabinets or glove boxes. This paper reports a modified Wilkins-Chalgren (MWC) medium for the culture of P. gingivalis under atmospheric conditions at 37 degrees C. On the basis of preliminary tests, WC broth was supplemented as follows: 500 mg/l cysteine hydrochloride; 250 mg/l sodium thioglycolate; and 1,000 mg/l sodium bicarbonate. Three P. gingivalis isolates (JKG-I, 33277 and A7436) showed very similar growth over 24 and 48 h periods when cultured both in WC medium in an anaerobic chamber and in the MWC medium. Culture of these isolates both in the anaerobic chamber and in the MWC medium yielded very similar data with respect to trypsin-like activity, total protease activity, and reactivity to monoclonal antibodies specific for P. gingivalis. Growth in the MWC medium varied over a 3- to 4-fold range for seven additional isolates (JKG-7, D86B6, D13B11, D84D2, JKG9, D67D9, D82F5) over 24 and 48 h periods.