Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, 600 036, India.
School of Ecology and Conservation, University of Agricultural Sciences, GKVK, Bangalore, 560 065, India.
Sci Rep. 2021 Jan 14;11(1):1478. doi: 10.1038/s41598-020-79239-5.
Camptothecin the third most in demand alkaloid, is commercially extracted in India from the endangered plant, Nothapodytes nimmoniana. Endophytes, the microorganisms that reside within plants, are reported to have the ability to produce host-plant associated metabolites. Hence, our research aims to establish a sustainable and high camptothecin yielding endophyte, as an alternative source for commercial production of camptothecin. A total of 132 endophytic fungal strains were isolated from different plant parts (leaf, petiole, stem and bark) of N. nimmoniana, out of which 94 were found to produce camptothecin in suspension culture. Alternaria alstroemeriae (NCIM1408) and Alternaria burnsii (NCIM1409) demonstrated camptothecin yields up to 426.7 ± 33.6 µg/g DW and 403.3 ± 41.6 µg/g DW, respectively, the highest reported production to date. Unlike the reported product yield attenuation in endophytes with subculture in axenic state, Alternaria burnsii NCIM1409 could retain and sustain the production of camptothecin up to ~ 200 μg/g even after 12 continuous subculture cycles. The camptothecin biosynthesis in Alternaria burnsii NCIM1409 was confirmed using C carbon labelling (and cytotoxicity analysis on different cancer cell lines) and this strain can now be used to develop a sustainable bioprocess for in vitro production of camptothecin as an alternative to plant extraction.
喜树碱是第三大需求的生物碱，在商业上从濒危植物印度喜树（Nothapodytes nimmoniana）中提取。内生菌，即居住在植物体内的微生物，据报道具有产生与宿主植物相关代谢物的能力。因此，我们的研究旨在建立一种可持续的、高产喜树碱的内生真菌，作为商业生产喜树碱的替代来源。从 N. nimmoniana 的不同植物部位（叶、叶柄、茎和树皮）共分离出 132 株内生真菌菌株，其中 94 株在悬浮培养中产生喜树碱。拟盘多毛孢（NCIM1408）和细极链格孢（NCIM1409）分别展示了高达 426.7±33.6μg/g DW 和 403.3±41.6μg/g DW 的喜树碱产量，这是迄今为止报道的最高产量。与在无菌状态下进行继代培养时内生菌报告的产物产量衰减不同，细极链格孢 NCIM1409 可以保留和维持喜树碱的产生，甚至在连续继代 12 次后仍能达到约~200μg/g。使用 C 碳标记（以及对不同癌细胞系的细胞毒性分析）证实了细极链格孢 NCIM1409 中的喜树碱生物合成，现在可以使用该菌株开发可持续的体外生产喜树碱的生物工艺，作为植物提取的替代方法。
