RT Journal Article SR Electronic(1) A1 Lev, M.YR 1959 T1 The Growth-Promoting Activity of Compounds of the Vitamin K Group and Analogues for a Rumen Strain of Fusiformis nigrescens JF Microbiology, VO 20 IS 3 SP 697 OP 703 DO https://doi.org/10.1099/00221287-20-3-697 PB Microbiology Society, SN 1465-2080, AB Summary: With a strain of Fusiformis nigrescens as test organism, the potencies of compounds of the vitamin K group were estimated, and the results compared with those from animal assay techniques. The compounds showed in the main the same relative activity for the micro-organism as for higher animals, with two exceptions: 1 : 4-naphthoquinone was highly active for F. nigrescens but is inactive for animals; phthiocol, which is active for animals, inhibited the response of F. nigrescens to menaphthone, i.e. phthiocol acted as an anti-vitamin K for the micro-organism. Most of the compounds tested were toxic in the range 1–5 µg./ml.; vitamins K1, K2 and a water soluble form of menaphthone (menaphthone bisulphite) were relatively less toxic., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-20-3-697