The Occurrence of a Soluble Lipase in Broth Cultures of Tubercle Bacilli and Other Acid-Fast Bacteria. Studies in Acid-Fast Bacteria. VI

Abstract

The growth of two rapidly growing strains of human tubercle bacilli in media of varied composition showed consistently two distinct phases in their metabolism: an initial phase characterized by rapid vegetative activity and progressive proteolysis, as indicated by a steady increase in ammonia formation; and a second phase marked by a progressive decrease in vegetative activity, and by recessive changes in metabolism, during which the ammonia accumulated during the initial phase gradually disappeared from the culture media (These Studies, I-V). This second phase, which appears to begin rather regularly after three weeks' growth in ordinary media with the organisms studied, is of unknown causation. It is quite probable that the accumulation of waste products plays a prominent part in restricting the activity of the organisms, but the simple restriction of bacterial growth per se does not explain the associated phenomenon of the recession of the ammonia which has been produced during the period of rapid development. Furthermore, attempts to correlate the recession of ammonia with the presence of certain substances in the media, in which these observations were made, were unsuccessful, for even in a culture solution as simple in composition as (NH,),HPO, NaC1, and dextrose, the same phenomenon was observed, suggesting strongly that the explanation of the recession is to be sought for in the organisms themselves. This at once focuses attention on the possibility of ferments, exoor endo-cellular, being concerned, the entire process, perhaps, being one in which autolysis plays a prominent part. The tubercle bacillus and other acid-fast bacteria are notoriously resistant to solvents which will promptly destroy other organisms not acid-fast. In the animal body, similarly, these bacteria are resistant to