Mass Production of Pure Gibberellin A₁ by Phaeosphaeria sp. L487 and the Fungal Preparation of [U-¹³C]Gibberellin A₁

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The mass production of pure gibberellin A₁ (GA₁) by shake-culturing Phaeosphaeria sp. L487 was investigated. Its GA₁ production was markedly influenced by natural nitrogen sources and NH₄NO₃. When the fungus was cultured in an 8% glucose−1.5% oatmeal−0.1% NH₄NO₃−0.5% KH₂PO₄−0.1% MgSO₄·7H₂O medium for 3 weeks, the amount of GA₁ in the culture filtrate was up to ca. 200 μg/ml: the addition of safflower oil to the culture medium two weeks after inoculation prolonged the GA₁-production period to produce 300 μg/ml. Further preparation of [U-¹³C]GA₁ as a tool for the analysis of a complex of GA₁ and its binding protein was attempted by using the fungus. The fungal culture in a [U-¹³C]glucose-oatmeal medium gave 6 mg of crystalline ¹³C-enriched GA₁. Its ¹³C-enrichment of ca. 75% and ¹J_CC values were determined by NMR spectrometry.