Source of the Phlei Growth Factor for Mycobacterium johnei

Abstract

IT was first shown by Twort and Ingram¹ that extracts of Mycobacterium phlei and certain other acid-fast bacilli contained a growth factor essential for the laboratory cultivation of Mycobacterium johnei. They² also obtained growth of M. johnei on media containing alcoholic extracts of certain food materials of cattle. Since extracts of organs of cattle did not contain this factor and since the principal lesions of Johne's disease are confined to the intestine, they concluded that food was the probable source of the growth factor in vivo. Francis et al. ³, however, obtained only a very slight stimulation of growth with some extracts of food materials, a stimulation which they considered to be due probably to substances unrelated to the growth factor; other extracts gave completely negative results. In all this work a form of inspissated egg was used as the basal medium.