Improvement of Curvulamine Production by Precursors Co-addition Strategy in Liquid Culture of Marine-Derived Fungus Curvularia sp. IFB-Z10.

Curvulamine, a novel scaffold alkaloid with remarkable selective antibacterial activity, is produced by marine fungus Curvularia sp. IFB-Z10. However, its deep pharmaceutical research and application are severely restricted by the low yield, which needs to be solved urgently. The purpose of this study was to improve curvulamine production via precursors co-addition strategy and further reveal the regulation mechanism. In this work, the optimal precursors co-addition conditions were firstly obtained, and curvulamine production achieved 166.74 mg/L with the supply of 250 mg/L alanine and 200 mg/L proline at 60 h, which was 4.08 times that of control. It was observed that under alanine and proline stimulation, fungus exhibited the morphology of a small-diameter compact pellet. Furthermore, the organic acid levels in central carbon metabolism (CCM) were declined with precursors supplement. Besides, precursors also induced the critical biosynthetic gene transcriptions. The above findings collectively promoted curvulamine synthesis. Finally, Curvularia sp. IFB-Z10 fermentation process was successfully established by feeding alanine and proline at 0.021 g/L/h and 0.017 g/L/h rate from 60 to 72 h, and curvulamine production reached 133.58 mg/L in a 5-L bioreactor. The information acquired would facilitate the enhancement of curvulamine yield in submerged fermentation and the research on synthesis regulation of other alkaloids.