TE ACTION OF SOME MEMBERS OF THE GENUS SERRATIA ON EGG YOLK COMPLEX

The enzymatic hydrolysis of lecithin has been studied by many workers using enzyme preparations from various animal and plant sources. The Italian work-ers (Contardi and Ercoli, 1933; Belfanti, Contardi, and Ercoli, 1936) in reports of their studies, and in reviewing the works of others, have given emphasis to the scope of the interest in the hydrolysis of this complex phospholipid. In the earlier report they described four lecithinases which may take part in the hydrolysis of lecithin. Lecithinase "A " attacks lecithin by splitting off the unsaturated fatty acid leaving lysolecithin. Lecithinase "B " can attack lecithin by splitting off both fatty acids, or, in the case of lysolecithin, the saturated fatty acid leaving glyc-erylphosphorylcholine. Lecithinase "C " (choline phosphatase) acts on lecithin by liberating choline. Lecithinase "D " (glycerophosphatase) hydrolyzes lecithin into a diglyceride and phosphorylcholine. Thus, the hydrolysis of this ester is particularly interesting inasmuch as the rupture of one or all of the four linkages in the molecule may give rise to one or all of its component parts (fatty acids, glycerol, phosphoric acid, and choline) or to fragments composed of two or more of the parts. Some studies have been made of the action of bacterial enzymes on lecithin. Macfarlane and Knight (1941) reported the production of phosphorylcholine and a diglyceride by Clostridium welchii, while Bard and McClung (1948), among others, have shown the presence of lecithinases in additional members of the clostridia. Felsenfeld (1944) reported that the vibrios with which he worked hydrolyzed lecithin. Quantitatively different rather than qualitatively different end products were produced by his organisms in the hydrolysis of the ester