MEASUREMENT OF PROTEASE THERMOSTABILITY, TWITCHING MOTILITY AND COLONY SIZE OF BACTEROIDES-NODOSUS

Total extracellular protease activity of Bacteroides nodosus in TAS liquid culture varied directly with cell mass and buffer concentration between 20 and 50 mM HEPES, MOPS and TES buffers, but not with Tris which gave anomalous high cell counts, nor with Na2Co3 which showed a decline of protease activity and cell mass. The stability of HEPES-buffered crude protease preparations were estimated on the basis of temperature or Ca2+ activity. Variation of the estimates for cellular twitching was greater than that for colony diameter in benign and virulent strains of B. nodosus. Surface translocation, quantified on the basis of colony diameter, reached a limit after 72 h incubation on modified TAS agar, ranging from 0.04 to 0.14 mm per h for six isolates tested. © 1990.