The Destruction of Acid-Fastness of the Tubercle Bacillus by an Autolytic Process.

There are several articles in the literature dealing with the subject of autolysis of the tubercle bacillus. AMcJunkin (1923) dehydrated living tubercle bacilli in 95 per cent ethyl alcohol for two minutes, suspended the microorganisms in oleic acid which contained a few drops of water, and incubated the mixture at 37°C. After several days, only a limited number of bacilli retained their acid-fast properties. The action was partially inhibited when the microorganisms were killed by heat or toluene. The experiments suggested to the author the "possibility that the solvent action was due to a thermolabile enzyme contained in the tubercle bacillus acting only in the presence of undiluted oleic acid." Boissevain (1926) obtained similar results using a number of different unsaturated fatty acids, but found that preliminary dehydration was unnecessary. Isabolinsky and Gitowitsch (1924, 1927, 1928) confirmed the results using lecithin, olive oil and liver oil. Steenken (1938) observed lysis of old colonies grown on solid egg media. Subsequent growth of secondary colonies within and surrounding the mother colonies showed evidence of lysis in their interior. Corper and Sweany (1918) noted that human and bovine tubercle bacilli, killed by toluene, liberated non-coagulable nitrogen on incubation at 37°C. Long (1921), on the contrary, found that 5 grams of moist organisms killed by toluene and incubated for two weeks liberated only 5 milligrams of soluble nitrogen. The liberation of such small quantities of soluble nitrogen appeared to Wells and Long (1932) to indicate that the microorganism had but weak autolytic powers. However, ouir observations, here recorded, indicate that there is present in the tubercle bacillus an active autolytic substance. It is common knowledge that virulent tubercle bacilli may remain in water for an indefinite period and still retain their acid-fastness. However, if, preliminary to their immersion in water, they are treated in the manner to be described, the bacilli not only lose their acid-fastness, but, with few exceptions, the structure of the microorganisms is completely destroyed. Experimental data will also be presented suggesting the probable nature of the agent responsible for the autolytic process.