Menaquinone Production and Utilization in Germ-Free Rats after Inoculation with Specific Organisms

Abstract

Although menaquinones are biologically active forms of vitamin K, factors that influence their production by bacteria or their absorption from the gut are not well understood. Germ-free rats were inoculated with four different strains of organisms and fecal and tissue menaquinone concentrations were determined. No menaquinones were detected in the tissues or feces of rats colonized with Bifidobacterium longum or Clostridium ramosum, two organisms that have not been reported to produce menaquinones when grown in pure cultures. Rats colonized with Bacteroides vulgatus had high levels of fecal MK-10 with significant amounts of MK-9 and MK-11, whereas rats colonized with Escherichia coli had high levels of fecal MK-8 and small amounts of MK-7. The same menaquinones are produced in pure cultures of these organisms. The predominant fecal menaquinones were also detected in liver and were present in higher concentrations in the liver of those rats not maintained in coprophagy-preventing cages.

Probiotics, Prebiotics, and Synbiotics: Gut and Beyond

“…Animal studies indicate that B. longum lacks the ability to synthesize vitamin C [162], and in vitro studies using the bacterial strain showed a decrease in vitamin K levels of the culture medium. Vitamin C acts as a growth factor for many bacterial strains, and since B. longum only requires low levels of the vitamin for its growth, we can interpret its ability to lower vitamin K concentrations in the surrounding area as a means of competing with other strains that depend on high vitamin K levels [163].…”

What can genome-scale metabolic network reconstructions do for prokaryotic systematics?

“…Black branches denote organisms (e.g. Bifidobacterium) that lack MKs and their biosynthetic genes (Kindberg et al 1987). Micromonospora carbonacea, whose genome encode for both the men and mqn genes, is marked with an arrow.…”

Vitamin K Deficiency

“…In a study by Kindberg and associates [45], menaquinones were measured in the intestine as well as the liver of germ-free rats inoculated with various species of bacteria. In 2 of the rats inoculated with bacteria, menaquinones were found in the liver; thus, there was the suggestion that some menaquinones were absorbed from the lower gut, although this appeared to be an inconsistent finding.…”