Many bacteria, such as Escherichia coli found in the large intestine, can synthesize vitamin K (menaquinone - 7 or MK - 7, up to MK - 11), but not vitamin K (phylloquinone). In these bacteria, menaquinone transfers two electrons between two different small molecules, during oxygen - independent metabolic energy production processes (anaerobic respiration). For example, a small molecule with an excess of electrons (also called an electron donor) such as lactate, formate, or NADH, with the help of an enzyme, passes two electrons to menaquinone. The menaquinone, with the help of another enzyme, then transfers these two electrons to a suitable oxidant, such fumarate or nitrate (also called an electron acceptor). Adding two electrons to fumarate or nitrate converts the molecule to succinate or nitrite plus water, respectively.
in large intestine vitamin k is formed by the activity of which bacteria
Many bacteria, such as Escherichia coli found in the large intestine