Studies in Carbohydrate Utilization by Organisms of the Genus Mycobacterium

Abstract

By means of direct quantitative carbohydrate determinations employing the Shaffer-Hartmann blood sugar method I have shown there is a rather wide utilization of carbohydrates by organisms of the genus Mycobacterium.

The reaction changes both in plain broth and carbohydrate broth cultures of the organisms of this genus are toward progressive increase in alkalinity. The reaction change is less rapid in the presence of utilizable carbohydrates. This increase in alkalinity whether in plain broth or carbohydrate broth cultures has been shown to be associated with an increase in the ammonia content of the media. This increase in ammonia is in most cases approximately equivalent to the increase in the titrable alkalinity. In other cases other substances either acid or alkaline in character, which are apparently derived from protein cleavage, are involved to some extent in the causation of the reaction changes and changes in titratable alkalinity. Such changes are accounted for by the ammonia increase equally as well in the carbohydrate broth cultures as in the plain broth cultures.

The ammonia production was found to be distinctly less for the production of a given amount of growth in the presence of utilizable carbohydrates. This diminished ammonia production was associated with a diminution in the degree of reaction change of the media. Also the higher the carbohydrate concentration, so long as it is within the limits that will permit growth, the less the ammonia increase and the less the reaction change of the media during the production of a constant amount of growth. Thus not only the presence, but also the concentration of a carbohydrate, is a factor determining the degree of protein sparing action it exerts.

The presence of utilizable carbohydrate does not directly have any effect upon the reaction change of the media.