The Function of Nicotinic Acid in Bacterial Metabolism

Abstract

In our previous publications (Kligler and Grossowicz 1938, 1939) we showed that nicotinic acid plays an essential part in the carbohydrate metabolism of certain members of the colon-typhoid group of bacteria-particularly Salmonella paratyphi A, Shigella dysenteriae and some strains of the Flexner type of dysentery. Our results indicated that nicotinic acid was not a growth factor in the limited sense, because growth occurred in its absence, but that it played the part of a codehydrase making available to the organism a source of energy which it could not use in the absence of nicotinic acid. The experiments reported in this paper were designed to test these findings and to account for the apparent contradiction between our results and those reported by Koser in his studies on Shigella paradysenteriae. EXPERIMENTAL Methods The same medium was used as in the preceding study. The basic salt mixture was sterilized by filtration through a Seitz filter and a sterile solution of S-K peptone added to give a concentration of 0.3 per cent. This peptone proved useful for these studies because available tests showed that it was free of nicotinic acid, or at any rate that the amount was less than that demonstrable by bacteriologic methods. To this basic medium were added the substances to be tested. Since many of our experiments were made with lactate (which is fermented aerobically) small Erlen-meyer flasks were used instead of test tubes. 173