[Biotin formation by the fungus Rhizopus delemar]

The capability of 26 collection micromycete strains to synthesize biotin and transform destiobiotin was investigated. Destiobiotin stimulated the biotin formation by the strains of the Aspergillus genus (except A. sclerotiorum synthesizing vitamin traces), the Fusarium genus, the Rhizopus genus (except Rh. nigricans), as well as Thighemella hyalospora and Sporotrichum sulfurescens. Among the strains tested Rhizopus delemar 1428 synthesized maximum quantities of biotin (over 300 micrograms/1). The biotin synthesis by this strain increased drastically when the fungal growth was terminated, about 90% of biotin being released into the medium. The rate of biotin synthesis and excretion grew significantly when the major portion of glucose was consumed and pH of the medium increased (to 8.0-8.2).