Study of Endophytic and Rhizospheric Fungi from Mappia nimmoniana (J.Graham) Byng & Stull for Camptothecin Analysis and Antibacterial Activity

Abstract

Camptothecin, the third essential and commonly used alkaloid is derived from the endangered Mappia nimmoniana (J. Graham) Byng & Stull plant in India for commercial use. In this study, endophytes from various plant parts (leaf, petiole, and stem) as well as a rhizospheric fungus associated with Mappia nimmoniana were isolated. M. nimmoniana was collected from Sawantwadi- Amboli, Sindhudurg, Maharashtra, India. The collection of plant material and rhizosphere soil samples was carried out using the method of Dongmo and Oyeyiola.  Ten fungi were isolated, including six rhizosphere fungi and four endophytic fungi. Out of 10 fungi, two endophytes and one rhizosphere fungus are reported to produce bioactive compounds, camptothecin, which were analysed using HPLC. The camptothecin-producing fungus was further identified using the ITS1/ITS4 molecular method. The presence of camptothecin in the fungus was confirmed by LC-HRMS analysis. Camptothecin levels in two endophytes were found to be 1.957 mg/100 mg and 0.3622 mg/100 mg respectively whereas the rhizospheric fungus recorded 0.1445 mg/100mg. In addition to that antibacterial activity of endophyte Fusarium falciforme and rhizosphere fungi Rhizopus arrhizus against Escherichia coli, Staphylococcus aureus and Bacillus subtilis was studied by the disc diffusion method.  It is observed that Fusarium falciforme shows significant antibacterial activity.