Detection of Microbial Lipase by Copper Soap Formation

Abstract

Copper soap formation as a test for the hydrolysis of fat (Carnot and Mauban, 1918) may be used for the detection of microbial lipase. METHOD To standard nutrient agar in the tube add 0.5 cc. per tube of melted butter of good quality and sterilize in the usual manner. The melted fat agar is cooled to 45°C., the fat well mixed in and the medium poured at once into a cold petri dish. On solidifica-tion the medium is inoculated by the streak method with the organism under test, and incubated at suitable temperature for forty-eight hours. The plate is then flooded with a saturated aqueous solution of CuS04 for ten minutes and rinsed gently with water. When the fat has been attacked conspicuous bluish-green streaks of insoluble copper soap appear on the plate. The in-tensity of the color is a rough gauge of lipolytic activity. In the case of palmitin the reactions involved may be repre-sented thus: