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In a study on the inhibitive effect of glucose, in media devoid of niacin, on the growth of bacteria requiring this vitamin for carbohydrate metabolism, it was noted that there exists a certain coordination between niacin and thiamine in the utilization of glucose by staphylococci. The experiments reported below were designed to elucidate the specific r6les of these two vitamins in the carbohydrate metabolism of these organisms.Knight, in 1937, was the first to demonstrate that Staphylococcus aureus can grow in a. synthetic medium containing cystine, tyrosine and tryptophane, provided the two vitamins niacin and thiamine are also added. He designated the vitamins as essential growth factors, but did not establish their specific function in the metabolic activity of these organisms. Subsequent metabolic studies have been made chiefly on resting cells previously grown either in media containing adequate amounts of both vitamins, or, as in the work of Hills (1938), in substrates relatively deficient in thiamine, but not in niacin. The authors referred to were concerned primarily with the nature of the breakdown of pyruvic acid, because of the part played by thiamine in this process in animals.The present investigations differ essentially from the previous studies in that they were conducted with growing cells and were designed to ascertain the r6le of these vitamins singly and together in the metabolism of glucose and the resulting acids. For comparison, a number of respiration tests were also made with resting cells. Experiments were conducted under both aerobic and anaerobic conditions. EXPERIMENTAL Procedure and methods. The staphylococci used in these experiments were isolated from furuncles. For preliminary orientation a large number of freshly isolated and stock strains were tested for their vitamin requirements.

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