[Biosynthesis of group B vitamins by yeasts--symbionts of xylophagous insects].

The biosynthesis of vitamins of the B group was studied in the yeasts Debaryomyces and Zygowillia--the symbionts of insects--xylophages. These yeasts provide the vitamins of the B group (biotin, thiamine, inositol, pyridoxine, nicotinic and pantothenic acids) for the preimaginal phases of insects--xylophages. The presence of these vitamins under the bark of trees and in other places of insect habitation is related to the viability of the yeasts. The content of the vitamins in the phloem depends on the quantity of the yeast organisms in it.