The biosynthesis of vitamin B₆ was studied by administering radioactive putative precursors to a mutant of Escherichia coli B., WG2. A new method for the isolation and purification of the vitamin congener, pyridoxol, is described. Partial degradation of the radioactive pyridoxol revealed non-random incorporation of a number of precursors into pyridoxol. On the basis of these results a biosynthetic scheme was constructed which envisages that pyridoxol is derived from three glycerol units. One of these is incorporated via pyruvic acid as a two carbon fragment at the oxidation level of acetaldehyde. The other two are incorporated intact, possibly by way of triose phosphate (Fig. 33). / Thesis / Doctor of Philosophy (PhD)