VITAMIN REQUIREMENTS OF HANSENULA YEASTS IN RELATION TO THEIR PHYLOGENY

Abstract

46 strains of yeasts representing 15 spp. of the genus Hansenula were studied and the specific B-vitamin requirements of 35 strains of 8 vitamin-requiring spp. were detd. The individual vitamin requirements of these yeasts corresponded quite generally to their ploidy characteristics except for Hansenula beckii and H. canadensis, diploids which merit special consideration due to their ecological relationships with bark beetles in conifer trees. All the other diploids, except H. subpelliculosa. did not need added vitamins, and this latter yeast had a marginal requirement for thiamin. The predominantly haploid yeasts, H. angusta and H. californica. required biotin and thiamin with pyridoxine as an accessory vitamin. Of the exclusively haploid yeasts. H. minuta required biotin with thiamin as a stimulatory factor, whereas H. capsulata needed biotin and thiamin with pyridoxine as an accessory factor. The ecologically restricted diploids, H. beckii and H. canadensis, required biotin, thiamin, and pyridoxine as essential vitamins.