Abstract
A strain of Serratia marcescens with marked lecithinase action has been isolated. It causes a selective hydrolysis of egg lecithin. In order to obtain the hydrolysis due to the choline phosphatase it is necessary to buffer the egg-lecithin emulsion at pH 8.8 with sodium tetraborate. Sodium tetraborate in quantities corresponding to 1.91% inhibits the lecithinase A and the lecithinase B of S. marcescens but not the activity of choline phosphatase. Choline phosphatase appears to be an endoenzyme and has been extracted from bacterial cells by means of water and toluene, and by means of ultrasonic disintegration. The inactivation of the enzyme by heat and the action of toluene on the enzyme have been studied. Boron in culture media causes morphological modifications of S. marcescens, which may appear as filaments. Thallium, gallium, and aluminum produce no morphological modifications.