STUDIES IN THE VARIABILITY OF TUBERCLE BACILLI: I. A RAPID-GROWING BOVINE TYPE

Abstract

Variability studies have been carried out on a considerable series of cultures of tubercle bacilli and related species of acid-fast bacteria. The present paper deals with a rapid-growing strain of the bovine tubercle bacillus. The results are in conformity with claims recently made by Petroff that certain types of tubercle bacilli undergo dissociation.It is shown that this avirulent, rapid-growing strain consists of R types which appear to be stable in acid fluid media and more or less stable on solid media. Rapid transfers through strongly alkaline fluids or growth in large volumes of similar media result in appreciable dissociation into S types. The S types were unstable, particularly in acid fluid media, and readily reverted to the R form.