Gut microbiota & Vitamin K

Dietary vitamin K is remodeled by gut microbiota and influences community composition. Menaquinone (MK) / Vitamin K2 is bacterially produced forms of vitamin K produced by the gut microbiota and consumed in the diet. The lack of dietary vitamin K changes the composition of the gut microbial community.
Ellis et al. 2021 GUT MICROBES 13: e1887721

Vitamin K2 forms an essential part of the electron-transfer chain in microorganisms that use respiration to energize the cell. Diet-derived Phytomenadione / Vitamin K1can be converted to Menaquinone (MK) / Vitamin K2
Nowicka & Kruk 2010 Biochim Biophys Acta 1797(9): 1587-605

Itis estimated to occur for 5-25% of digested Phytomenadione / Vitamin K1
Shearer & Newman 2008 Thromb Haemost 100(4): 530-47
Okano et al. 2008 J Biol Chem 283(17): 11270-9

Despite this interconversion, Phytomenadione / Vitamin K1 concentrations in animal tissues are deficient compared with MKs, particularly Menaquinone (MK) / Vitamin K2
Okano et al. 2008 J Biol Chem 283(17): 11270-9

Some gut microbes in mammals contain genes that encode enzymes for Menaquinone (MK) / Vitamin K2 production through one of two pathways.
Hiratsuka et al. 2008 Science 321(5896): 1670-3

The major Menaquinone (MK) / Vitamin K2 component in many Gram-positive spore-forming bacteria is Menaquinone (MK7); in Escherichia coli, it is Menaquinone (MK8)
Kurosu & Begari 2010 Molecules 15(3): 1531-53

Within the genus Bacteroides, the long-chain forms Menaquinone (MK10), Menaquinone (MK11), Menaquinone (MK12) are primarily synthesized
Ramotar et al. 1984 J Infect Dis 150(2): 213-18
Mathers et al. 1990 Br J Nutr 63(3): 639-52
Suttie 1995 Annu Rev Nutr 15: 399-417

see also:
Gut microbiota & Vitamins
Menaquinone (MK) / Vitamin K2 & Isoforms
Vitamin K