Temporal relationships and characterisation of extracellular proteases from benign and virulent strains of Bacteroides nodosus as detected in zymogram gels.

Extracellular proteases produced by Bacteroides nodosus in a peptone rich modified trypticase-arginine-serine broth medium were separated and characterised by relative mobility (Rf) in electrophoretic zymogram gels. One benign and two virulent protease banding patterns were established with isolates from sheep, cattle and goats. They correlated with other laboratory tests for virulence but were independent of serogroup. The electrophoretic zymogram method was unable to differentiate intermediate from virulent strains. The time required for the production of maximum levels and numbers of protease bands was four to five days for benign and five to six days for virulent B nodosus. Elevated temperatures (above 45 degrees C) and pH extremes (below pH 6 and above pH 9) modified the electrophoretic banding patterns. The molecular weights of the proteases ranged from 8000 to 43,000 daltons and the isoelectric points from pH 4.90 to 5.90. They are serine proteases and this property can be utilised in affinity purification of these molecules.