Comparative Study of in vivo and in vitro Grown Mycobacterium tuberculosis. III. Lipid Composition.

Abstract

A comparative analysis of the lipid composition of in vivo and in vitro grown M. tuberculosis of the same strain H37Rv has revealed a statistically significant difference in per cent lipid content for each of 3 solvent fractionating systems, as well as in total lipid concentration. Preliminary examination, by means of gas-liquid-chromatographic (GLC) analysis, of the fatty acids isolated from the ether-alcohol extracts did not show any striking difference between the two types. There is, however, a trend indicated in the direction of a greater percentage of longer chain fatty acids present in the lipids of the in vitro cultured tubercle bacilli. Palmitic and stearic acids are present in large amounts in both cases, plus a complex array of both normal and branched acids ranging from C10 without interruption up to C32. The presence of the C27-phthienoic acid in the lipids of the in vivo organism, while indicated by GLC, cannot be demonstrated solely from this evidence.