The B-Vitamin Requirements of the Propionibacteria.

The nutritional requirements of the Propionibacteria have long been regarded as complex. It has been shown that amino acids, although beneficial, are not essential (Fromageot and Loroux, 1936; Tatum, Wood and Peterson, 1936a; Wood, Anderson and Werkman, 1938). They may be replaced by (NH4)2SO4, but growth of many species is seriously impaired upon such a medium. Thiamin has been reported by Tatumn Wood and Peterson (1936b) as stimulatory to certain species. However, Silverman and Werkman (1939) found that cultures could be "trained" to grow vigorously in its absence. Riboflavin has been reported by Wood, Anderson and Werkman (1938) as stimulatory, but it can apparently be dispensed with (Krauskopf, Snell and Peterson, 1939). Pantothenic acid has been shown by Krauskopf, Snell and Peterson (1939) to be required by several species. No success in the culturing of any of these organisms on a completely synthetic medium has been reported. Perhaps the nearest approach was that of Wood, Tatum and Peterson (1937), who succeeded in growing a number of species in a synthetic (NH4)2SO4 medium supplemented with an ether extract of an aqueous yeast extract. Growth was rather meager, however, and addition of hydrolyzed casein was necessary for sub-culturing. It was the purpose of this investigation to ascertain which, if any, of the Propionibacteria could be grown on an essentially synthetic medium containing all of the known B-vitamins; and, if growth were obtained, to show which of the vitamins were essential for growth. The organisms investigated were the following: Propionibacterium jensenii (1), P. jensenii (29), P. pentosaceum (4), P. thonii (15), P. rubrum (19), P. peterssonnii (20), and P. technicum (22), all derived from Van Niel's strains (1928); and P. arabinosum, and P. zeae, derived from Hitchner's (1932) original strains.