Comparative Studies of the Action on the Pneumococcus of Bile Acids and Unsaturated Fatty Acids, Found in Bile in the Form of Soaps

Ox bile contains the soaps of unsaturated higher fatty acids not only with one, but also with two and more than two double bonds, in a dilution of about 1:600. These substances, when isolated from bile, exert an antiseptic action on the pneumococcus in a dilution of approximately 1:50,000 and kill the organism in a dilution of 1:5000 in approximately 1 hour. As their action is, then, about 100 times stronger than that of the conjugated bile acids, their presence in bile should be considered, whereas hitherto it has been entirely overlooked not only by bacteriologists but by physiologists as well. Since the soaps of unsaturated fatty acids do dissolve the pneumococcus cell in broth culture, Neufeld's (12) conclusion, is no longer valid.