The Chemistry of the Lipids of Tubercle Bacilli

The high percentage of lipids differentiates the tubercle bacillus and acidfast bacteria in general from other microorganisms. However, the amount of lipids in acid-fast. bacteria varies not only from strain to strain but also with the composition of the medium (1). Results obtained in this laboratory indicate that the lipids of the human tubercle bacillus, Strain H-37, when grown under identical conditions but at different times on the Long synthetic medium (2) show wide variations in the amounts of various lipid fractions and also in chemical constants (3, 4). Similar variations were found in this laboratory in a comparative investigation of five different strains of human tubercle bacilli, four of which had been recently isolated from human cases of tuberculosis (4). In other investigations? conducted in this laboratory on the chemistry of the pathogenic microorganism Phytomonas tumefaciens it was found, when the bacteria were cultivated in a synthetic medium in which glycerol was the chief source of carbon, that the growth was slight and the bacterial cells contained only 2 per cent of lipids. However, when sucrose was added to the medium in place of glycerol, the bacterial growth was more luxuriant and the lipid content of the bacteria amounted to about 6 per cent (5). In view of the results with Phytomonas tumejaciens it appeared of interest to study the lipid production and the chemical composition of the lipid fractions of the human tubercle bacillus when cultivated on a modified Long synthetic medium in which glycerol was replaced by dextrose. Through the cooperation of Sharp and Dohme, Glenolden, Pennsylvania, we were provided with a lot of tubercle bacilli, Strain H-37, which ha,d been cultivated on the modified Long synthetic medium. The bacilli were extracted and the lipid fractions were separated essentially as described in previous studies (4). According to the results of our earlier investigations the alcohol-ether