EXTRACELLULAR LIPA SE ACTIVITY CHARACTERIZATION OF SOME PSEUDOMONAS AERUGINOSA STRA INS ISOLATED FROM HUMAN INFECTIONS

Pseudomonas aeruginosa EF2, ATCC 9027 and ATCC 19660 were grown in a continuous culture under Tween 80 (polyoxyethylene sorbitan monooleate) limitation and optimum conditions (pH 6.5, 37°C at dilution rate of 0.05/h). Culture supernatants were carefully removed and stored at -20°C. To purify the lipases, the culture supernatant was reduced in volume to approximately 10 mL by an ultrafiltration unit. Excess salts were removed and extracellular lipase was purified. Biochemical characterization and SDS polyacrylamide gel electrophoresis suggested that lipase particles consisted of protein and carbohydrate-including lipopolysaccharide-with the major enzyme activity being lipase. Lipase activity was measured as the rate of standard olive oil (predominantly triolein) hydrolysis. Characterization of the purified extracellular lipases was then investigated by hydrolysis activity, interesterification reactions and effect on the chemotaxis and chemiluminescence reactions on human peripheral blood neutrophils and monocytes. It was shown that lipase from the EF2 strain was the most effective enzyme used and monocytes were much more sensitive to lipases than neutrophils. Since monocytes are one of the most important cells of the host defence system, lipase activity of Pseudomonas aeruginosa may contribute to the pathogenesis of infections caused by this Gram-negative bacterium.