ON THE EXISTENCE OF TRICARBOXYLIC ACID CYCLE IN SALMONELLA TYPHI AND PARATYPHI A

Abstract

The present authors have already reported some aspect on the existence of the tricarboxylic acid cycle in Salmonella typhi and paratyphi A from the point of cultural adaptation. When Salmonella typhi or paratyphi A is cultivated in a medium, in which the sole carbon source is one of the tricarboxylic acid cycle members, they behave quite identically so that it seems to us reasonable to regard these two types of Salmonella as identical in respect of tricarboxylic acid cycle operation. In the previous reports, we considered that the tricarboxylic acid cycle might not operate in Salmonella typhi or paratyphi A from the experimental results, which show that the cultures of these organisms adapted and passaged serially in the medium, carbon source of which is only citric acid, has not been adapted to α-ketoglutaric acid. However, at that time we did not take into consideration the permeability of the cell membrane purposely, and discussed the results solely from the point of successive adaptation of bacterial biochemical activity. And now, we have come to the point to discuss them from the viewpoint of the permeability of cell wall.
As seen from our experimental results, the main point of the problem lies in the reaction series, in which α-ketoglutaric acid is produced from citric acid. In this time, first, experiments by cultural adaptation was performed also with isocitric acid in order to know what attitude this acid takes in an experiment like this. Next, cell-free extract was made from bacterial cells of Salmonella typhi and its aconitase activity and the activity of the reaction, isocitric acid → α-ketoglutaric acid, was examined.