The Relative Activity of the Soluble Lipase and Lipase Liberated during Autolysis of Certain Rapidly Growing Tubercle Bacilli. Studies in Acid-Fast Bacteria. VII

Abstract

In the previous article,' experiments were recorded which demonstrated that an active fat-splitting ferment was present in solution in broth cultures of a variety of acid-fast bacilli. These experiments were carried out in such a manner as to be roughly quantitative, and the activity of the lipase, as determined by these experiments, was found to be very considerable. It is a matter of importance to determine whether these lipases are excreted by these acid-fast bacilli as exoferments, or whether they are bound up in the bodies of the bacteria, and appear in solution only when the bacteria have autolyzed (endoferments). Carrikre2 has described a thermolabile lipase in the organisms of a six-months-old culture of the tubercle bacillus; his observations suggest that this lipase was an endo-ferment and that even minute amounts of culture medium destroy or inactivate it. This observation is not in harmony with the results presented above, for the lipase of the acid-fast bacteria described there was present and active in the culture medium, and it was thermostabile. It is possible, however, that the lipase, which is demonstrable in younger cultures of tubercle bacilli, may have disappeared, as the cultures were incubated for a longer period, without affecting the activity of a second thermolabile endo-lipase which is locked up within the bacteria themselves. The following observations were undertaken with a view of determining the relative amounts of lipase, respectively, in the culture medium and in the bodies of the bacteria grown in the culture medium. The cultures (various acid-fast bacilli) were of unequal ages, as indicated in Table 1. Various degrees of autolysis of the bacteria, therefore, must have taken place, depending on the strain of organism studied and the length of incubation.