Biosynthesis of Vitamin B6 by a Yeast Mutant

摘要

The gradient-plate technique was employed to isolate mutants of Saccharomyces marxianus (NRRL-Y-1550) which, when grown in a synthetic culture medium, excreted about 2 μg/ml of vitamin B₆ as ascertained by microbiological assay. The major component that possessed vitamin B₆ activity was isolated by ion-exchange column chromatography and identified as pyridoxol by ultraviolet and fluorescence spectroscopy, as well as by paper chromatography and various chemical tests. Pyridoxal was also identified as one of the excreted compounds. Two other compounds that possessed vitamin B₆ activity were excreted in smaller quantities in the growth medium and have not yet been identified; they are not phosphates of vitamin B₆. The amount of vitamin B₆ excreted was not increased when the mutant was grown in the presence of various oxidation products of this vitamin. The methods and results reported here may be helpful in future studies on the biosynthesis of vitamin B₆.