Vitamin Requirements of the Genus Propionibacterium.

The literature concerning the nutrition of the propionic acid bacteria was reviewed by Thompson (1943). He attempted to determine which of the Propionibacterium species could be grown on synthetic media containing B vitamins and, if growth occurred, to show which vitamins were required. He was able to grow satisfactorily through repeated subculture five out of nine cultures. All five of these cultures capable of growth after repeated transfer required pantothenic acid, and four required biotin. Thiamine and p-aminobenzoic acid (PAB) appeared to be necessary or at least stimulatory in some cases. Preliminary investigations in our laboratory concerning the nutritional characteristics of a few species, undertaken in the course of studies concerning the mechanism of propionic acid formation, indicated that under conditions of large inoculum the nutritional demands of these few cultures were very simple insofar as ability to undergo repeated transfer was concerned. Further studies revealed that with 25 different cultures representing 9 different species the only absolutely required B vitamins were pantothenic acid and biotin, with a few cultures requiring either PAB or thiamine for growth beyond the fifth or sixth serial transfer. Pantothenic acid alone was found to suffice for 3 of the 25 cultures. With all cultures growth was obtained through 15 serial transfers on media of known B vitamin content without loss in abundance or rapidity of growth, thus eliminating the possibility of transfer of growth factors through the inoculum.