Growth Stimulator for Blfidobacteria Produced by Propionibacterium freudenrelchii and Several Intestinal Bacteria

A bifidogenic growth stimulator was present in the cell-free filtrate of Propi­ onibacterium freudenreichii 7025 culture and in the methanol extract fraction of the cells. Several intestinal bacteria, such as Bacteroides, Enterobacter, and En­ terococcus, which also released a growth stimulator for bifidobacteria, may play an important role in regulation of a bi­ fidobacterial population in colonic microflora. The water-soluble stimulator from the methanol extract of the cells was partially purified. The molecular weight of the stimulator appeared to be <3000. The stimulatory activity was un­ affected by treatments with pronase, carboxypeptidase A, ribonuclease, or nuclease PI and was heat stable over a wide pH range. This stimulator differed from cyanocobalamin and from organic acids, such as acetate and propionate. Because it was stable to heat and proteo­ lytic enzymes, the stimulator is a useful bifidogenic factor that can reach the large intestine while retaining its ac­ tivity. Short-chain fatty acids were highly inhibitory to the growth of many intesti­ nal bacteria, particularly Gram-negative facultative and obligatory anaerobes. The short-chain fatty acids (especially propi­ onate) stimulated the growth of bi­ fidobacteria. The growth of Bifidobac­ terium adolescentis 6003 was further enhanced in the presence of short-chain