Abstract
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 1JCC values were determined by NMR spectrometry.