Endophytic fungus Diaporthe caatingaensis MT192326 from Buchanania axillaris: An indicator to produce biocontrol agents in plant protection.

The study aims at the Isolation, screening and antibacterial evaluation of Camptothecin (CPT) and its derivatives, an anticancer molecule from endophytic fungus Diaporthe caatingaensis MT192326 of the medicinal plant, Buchanania axillaris. Plant parts were collected from Sathyamangalam Tiger Reserve forest, Tamil Nadu. The fungus was isolated using DEKM07 medium was used as the screening medium for the presence of CPT. The strain with the highest yield of CPT was identified at the molecular level by 18S rDNA sequencing. CPT was isolated and analyzed by UV-Vis spectrophotometry, Thin layer chromatography, High-Performance Liquid Chromatography, Fourier Transform Infrared spectroscopy, and Electron spray ionization-mass spectrometry. The compounds identified by ESI-MS from the fungal extract were studied for their antibacterial assays against procured MTCC bacterial pathogens. The maximum yield of 0.681 mg/L of CPT was produced by the fungus D.caatingaensis. CPT derivatives were identified at m/z of 305, 348 and 389 through ESI-MS analysis. Antibacterial studies revealed that the endophytic fungal extract compounds were studied for antibacterial activities of disc diffusion assay, exhibiting a growth inhibition range of 15-22 mm in nutrient agar plate medium. The Minimum Inhibitory Concentration revealed the antibacterial potential at a lower concentration of 12.5-25 μg/ml with all bacteria studied. The relatively lower antimicrobial efficacy of partially purified bio-metabolites than the positive control streptomycin (3.125) concentration could be due to the presence of derivatives of the compounds that hinder the activity of the biometabolite. This is the first initiative to screen, isolate and analyze the antibacterial assays of CPT and derivatives from endophytic fungus D.caatingaensis of ethnopharmacologically important B.axillaris plant from STRF.