Many bacteria, such as Escherichia coli found in the large intestine, can synthesize vitamin K2 (menaquinone-7 or MK-7, up to MK-11), but not vitamin K1 (phylloquinone).
Vitamin K – Wikipedia
en.m.wikipedia.org › wiki › Vitamin_K
Gut bacteria that produce k2:
www.intechopen.com/books/vitamin-k2-vital-for-health-and-wellbeing/menaquinones-bacteria-and-foods-vitamin-k2-in-the-diet
k2 lower INR:
www.ncbi.nlm.nih.gov/pubmed/23530987