SO-CALLED FREE LIPIDS FROM BRUCELLA ABORTUS BANG - NEUTRAL LIPIDS

Two different strains of Brucella abortus, strain 1119 and strain Scherle II, were grown on solid media; strain 1119 was harvested after approximately 70 h, strain Scherle II was harvested at different ages of the culture up to 72 h. The “free” total lipids were extracted and from these the neutral lipids were prepared and analyzed. The following results were obtained. Strain 1119 contains 4.5% free lipids of bacterial dry weight. Strain Scherle II contains decreasing amounts of free total lipids from approximately 6% to 1.4% as the age of the culture increases. On a weight basis the free total lipids of strain 1119 contain 8.1% neutral lipids. The neutral lipids of strain Scherle II decrease from more than 60% to approximately 24% (of free total lipids) with increasing age of the culture. The amount of phospholipids, however, remains comparatively constant (in relation to the percentage of total lipids) with increasing age of the culture of strain Scherle II. The results indicate that polar lipids other than phospholipids accumulate as the age of the culture increases, but there is no net storage of lipids. The neutral lipids of strain 1119 contain approximately 30% (on a weight basis) of ubiquinone‐50 (corresponding to 1.2 μmoles/g bacterial dry weight). Strain Scherle II also contains ubiquinone‐50, but in amounts demonstrable by thin‐layer chromatography only after an age of 36–38 h. Ubiquinone‐50 has hitherto been found only in a few bacterial species, while most bacterial species contain lower isoprenologs of ubiquinone. The neutral lipids of strain 1119 contain 51% (on a weight basis) of diglycerides, consisting of the 1,3‐ and the 1,2‐isomers. In strain Scherle II only 1,2‐diglycerides were found. The component fatty acids of the diglycerides of strain 1119 consist of approximately 55% (on a weight basis) of C19 cyclopropane acid (lactobacillic acid). The lactobacillic acid/cis‐vaccenic acid ratio is fairly independent of the age of the culture of strain Scherle II. The amount of unesterified fatty acids is lower in strain 1119 (4.9% of the neutral lipids, on a weight basis) than in strain Scherle II (49 or 67%, according to the culture conditions). Both strain 1119 and strain Scherle II contain probably small amounts of triglycerides, monoglycerides and long‐chain hydrocarbons. The possible significance of the results in the classification of Brucella is discussed. Copyright © 1969, Wiley Blackwell. All rights reserved