Phospholipase A activity in supernatants from cultures of Bacteroides melaninogenicus

The phospholipase A activity in culture supernatants of two strains of Bacteroides melaninogenicus is described. The enzyme utilize phosphatidylcholine as substrate and produce mainly lysophosphatidylcholine and free fatty acids. The activities are Ca2+-independent, are not affected by the presence of a chelating agent, have a broad pH range (5-9) and an optimum temperature for activity of approx. 50 degrees C. The activity in a growing bacterial culture increases from the end of the lag phase to the late exponential phase of growth. Analysis of the products resulting from the actions of the enzymes on L-alpha-palmitoyl-beta-oleoyl[1-14C]phosphatidylcholine indicates that the enzymes are phospholipase A1 (EC 3.1.1.32).