Abstract
Various compounds, either alone or with pimelic acid, have been studied with respect to their influence on the biosynthesis of biotin by Aspergillus niger growing in synthetic medium. Biotin and/or biotin vitamers synthesized were determined by microbiological assay with Neurospora crassa. Of the more than forty new compounds screened, only lipoic acid and some lipoic acid derivatives showed any effect. Lipoic acid and derivatives did not stimulate biotin biosynthesis in the absence of pimelic acid, but, when added to the synthetic medium in conjunction with pimelic acid, a three- to fivefold enhancement of the pimelic acid stimulation of biotin biosynthesis occurred. 8-Methyl lipoic acid, as well as 5-lipoic acid, antimetabolites of lipoic acid in pyruvate oxidation, were equally active. Growth of A. niger on medium containing lipoic acid- 35S and pimelic acid did not yield radioactive biotin. The possibility that lipoic acid is stimulatory because of promoting sulfate reduction is suggested.
Published Version
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