Isolation and Chemical Structural Elucidation of Antibacterial Bioactive Compounds from Endophytic Fungal Strain Phoma sp. D1

The present investigation has been performed for the isolation, optimization, and chemical characterization of antibacterial compounds from endophytic fungi that survive inside the internal tissues of plants without causing any symptoms. Endophytic fungi were isolated from four medicinal plants and screened for their antibacterial activity. The fungal strain Phoma sp. D1 showed maximum antibacterial activity at 18.25 ± 0.58, 22.75 ± 0.85, 19.30 ± 0.76, and 16.30 ± 0.65 against Klebsiella pneumoniae , Bacillus subtilis , Escherichia coli , and Staphylococcus aureus , respectively. For maximum production of antibacterial compounds, Phoma sp. D1 was further optimized on different sources such as culture media, pH, temperature, carbon and nitrogen sources, and incubation period. The optimum culture media, pH, temperature, carbon and nitrogen, and incubation period for bioactive metabolite production of the strain were recorded in SDB, dextrose, yeast extract, 25 ± 0.1, and pH 8.0. The purification and chemical characterization of the antibacterial compounds were done by using solvent–solvent extraction, thin-layer chromatography, and gas chromatography and mass spectroscopy. The chemical characterization of the extract from Phoma sp. D1 showed the presence of five compounds, 2-(-cyclohexenyl) ethylamine, 2-chloro-6 fluorophenol, butyl ether2-hydroxyskatole4-glycerol, p-coumarate, and bicyclo [4,2,1] nona-2,4-dien-9-one could be responsible for antibacterial activity. The computation observation of biomolecules through DFT, QSAR, EHOMO, and ELUMO was also performed.