It was not possible to grow Leptospira canicola beyond the third passage unless the medium contained gelatin. In the presence of gelatin, only enanthic acid and valerianic acid among the short-chained fatty acids showed distinct growth promotion. Continuation failed only after the 7th passage. Of the longer fatty acids, palmitic acid, stearic acid, oleic acid and Tween 80 showed good growth. Growth was so intense in the case of palmitic acid and stearic acid that the tube showed 50-100 leptospirae in the field one week after inoculation. 22 passages were made through nutrient containing palmitic acid. This series frequently furnished starting material for passages through other fatty acids. The concentration of fatty acids was highly significant. Fatty acids at .01 m and .001 m inhibited growth or killed the leptospirae in the first passage. Weaker concentrations of .000001 m or less no longer permitted reproduction. Most favorable were oleic acid in concentrations of .0001 m and . 00001 m, stearic and palmitic acid at .0001. Tween 80 gave good growth, but only in the presence of gelatin, in concentrations of 28.2 to 0.00282 mg. The best results were achieved at higher concentrations of 28.2 and 2.82 mg. More than 100 organisms were counted in the field.
Trans. of Zentralblatt fuer Bakteriologie, Parasitenkunde und Infektionskrankheiten. Abt. 1. Originale (West Germany) v169 p269-274 1957.