Production of cyclosporins by Tolypocladium niveum strains

Abstract

Nine strains of Tolypocladium niveum (= inflatum) were compared for their production of cyclosporins. Two of the strains, which were originally from the parental NRRL 8044 strain, were among the lower producers, while seventeen Tolypocladium strains belonging to seven other species produced no detectable cyclosporins. Variable cyclosporin production was observed initially. Once extraction and quantitation methods had been established, spore inoculum density and cultural morphology and carbon and nitrogen sources were found to be among the variables affecting cyclosporin production. Cyclosporin A was identified by cochromatography by using high-performance liquid chromatography, and cyclosporins A, B, and C were identified by gas chromatography-mass spectroscopy; all three compounds exhibited biological activity. They were routinely produced as a mixture in the ratio 7:1:2 in T. niveum UAMH 2472, which was selected on the basis of single-spore isolate total cyclosporin production and was used for most studies. This strain routinely produced total cyclosporin levels of 150 to 200 mg.liter-1 after 12 days of growth on a 2% sorbose-1% vitamin assay Casamino Acids medium.