Amesia nigricolor, a novel endophyte of Encephalartos bubalinus, exhibiting a robust taxol biosynthetic stability: chemical characterization and biological activities.

Diminishing the productivity of Taxol by the potential fungi with storage is the key hurdle that impedes their applications to be an industrial platform for Taxol production. Thus, exploring of a fungal isolate with a reliable robustness for Taxol biosynthesis is the objective of this study. Although, Encephalartos bubalinus has diverse ethnopharmaceutical properties, however, the identity of its endophytic fungi remains poorly explored. Therefore, the endophytic fungi inhabiting this plant has been isolated and characterized, and their Taxol productivity was assessed. Amesia nigricolor OR364127.1, an endophyte of E. bubalinus, was characterized as the potent biologically active and Taxol producer (105 μg/l). The sample identity was resolved from the HPLC, FT-IR and MS/MS analysis, with the molecular mass/ fragmentation pattern was identical to authentic one. The extracted Taxol of A. nigricolor had a strong activity against the HepG2 (IC₅₀ 19 nM) and MCF7 (IC₅₀ 23 nM) with a selectivity index 13.2 and 11.9 to the normal Vero cells. Taxol of A. nigricolor had a powerful anti-wound healing, and apoptotic properties, with ability to stop the G2/M cell cycle, ensuring their consistent biological activity to the authentic one. The Taxol yield by A. nigricolor was enhanced by 2 folds (205.2 μg/l), with the statistical bioprocessing by CCD. The half-life time for production of Taxol by A. nigricolor was more than 10 months, that being higher than those reported for various Taxol-producing fungi, ensuring the relative stability of the biosynthetic machinery of Taxol by A. nigricolor with storage as solid cultures at 4°C. A relative restoring to the Taxol productivity by A. nigricolor was noticed with ethylacetate extract of E. bubalinus, ensuring the presence of chemical signals inducing Taxol productivity by A. nigricolor. To the best of our knowledge, this is the first recorded endophytic fungus "A. nigricolor EFBL-AG" with a relative stability of Taxol biosynthetic machinery.