EVIDENCE FOR PHOSPHOLIPASE-B ACTIVITY IN FUSOBACTERIUM-NECROPHORUM CULTURES AND ITS ASSOCIATION WITH HEMOLYSIN LEUCOCIDIN ACTIVITIES/

Phospholipase B (PLB) activity was present in Fusobacterium necrophoru m cultures and it correlated closely with virulence and co-purified wi th the hemolysin/leucocidin activities. All three activities were asso ciated with a large molecule or molecular complex (6 X 10(2)-2 X 10(3) kDa) exhibiting varying degrees of aggregation. These were present ma inly in the culture medium and to a lesser extent in cell sonicates. T he PLB and toxin activities were sensitive to heat, dissociating agent s, proteolyric enzymes, prolonged purification regimes, freeze-drying and repeated freeze-thawing. The toxin(s) were stable over a broad ran ge of pH, did not require divalent ions or reducing agents and could b e kept for several months as an ammonium sulfate precipitate at 4 degr ees C, or stored as a concentrated liquid in the presence of proteolyt ic inhibitors at -20 degrees C.