Supplementary growth promoting effect of 2-methyl-1,4-naphthoquinone of Lactobacillus bifidus var. pennsylvanicus.

Many investigations have been carried out concerning the ability of microorganisms to synthesize vitamin K. These investigations were stimulated by the observation that the vitamin K isolated from fish meal by Almquist and Stokstad (1935) originated from a bacterial contaminant. The subject has been summarized by Peterson and Peterson (1945) who, in comparing various microorganisms for this biosynthetic ability, have indicated the extreme variation in the amount of vitamin K produced. In contrast to the synthetic ability, only a few species have been reported which require vitamin K for growth. Woolley and MeCarter (1940) were first to demonstrate such a requirement when they observed that 2-methyl-3-hydroxy-1 , 4naphthoquinone (phthiocol) would replace dried cells of Mycobacterium phlei in increasing the growth of MIycobacterium johnei. Schmidt and Busing (1942) demonstrated a comparable effect with 2-methyl-1,4-naphthoquinone (menadione) for Escherichia coli. Vinet (1945) recognized the growth-promoting action of vitamin K and menadione on Aspergillus niger. Recently, Lev (1958) demonstrated a vitamin K requirement for a rumen strain of Fusiformis nigrescens. Lactobacillus bifidus var. pennsylvanicus, a mutant requiring for growth human milk or more specifically, N-acetyl-D-glucosamine-containing saccharides, was isolated from feces of breast-fed infants (Gy6rgy et al., 1952). Recently, Petuely (1957) has claimed that lactulose (4-0-f-Dgalactopyranosyl-D-fructofuranose) when added to a properly constituted milk formula will promote the growth of L. bifidus in the intestinal tracts of infants. Lactulose possessed no growth promoting effect in vitro on L. bifidus var. pennsylvanicus. We did find, however, that a preparation of crude lactulosel enhanced the growth of this microorganism in the presence of