Characterization of lipolytic activity associated with a Vibrio species of bacterium isolated from fish intestines

Cultures of a species of Vibrio isolated from fish intestines and known to synthesize the polyunsaturated fatty acid eicosapentaenoic acid (20:5n-3) were incubated with di-[1-C-14]palmitoyl phosphatidylcholine to determine if lipolytic enzymes are produced by the bacteria. After two days of culture, most radioactivity was recovered in the phospholipids of the bacterial cells. When supernatants from cultures of the Vibrio were incubated with either di-[1-C-14]palmitoyl phosphatidylcholine, 1-palmitoyl-2-[1-C-14]linoleoyl phosphatidylcholine or 1-[1-C-14]palmitoyl lysophosphatidylcholine almost all radioactivity was recovered in the free fatty acid fraction after 24 h. Only very small levels of radioactivity from di-[1-C-14]palmitoyl phosphatidylcholine were recovered in diacylglycerols and phosphatidic acid. Over the same incubation period 61% and 5% of the radioactivity originally present in glycerol tri-[1-C-14]oleate and cholesteroyl [1-C-14]oleate, respectively, was released to free fatty acids. Soybean phosphatidylcholine and cod roe phosphatidylcholine, which differed in polyunsaturated fatty acid profile, were both hydrolyzed by culture supernatant. The results suggest that the Vibrio species examined produces a phospholipase B capable of hydrolyzing both intact phospholipids and lysophospholipids.