Abstract
Using a sensitive fluorometric method, the contents of NAD and NADP in various strains of lactic acid bacteria were measured and they were compared with those in some other microorganisms. The contents of the two coenzymes in lactic acid bacteria were found to be astonishingly high, as exemplified by the NAD content found in some strain which was as high as 0.78% of cell dry weight. Among the lactic acid bacteria tested, homofermentors in general were found to contain more NAD and less NADP compared with heterofermentors. The experiment, in which the levels of the coenzymes in L. plantarum were regulated by varying the quantity of nicotinic acid in the medium, showed that the racemiase activity of the cells was markedly dependent upon the intracellular concentration of NAD, while it was not the case with the glycolytic activity of the same cells. Some discussions were made on the significance of high level of NAD in lactic acid bacteria.
