The Antibacterial Activity of Crude Extracts of Secondary Metabolites from Bacterial Endophytes Associated with Dicoma anomala

Abstract

Endophytic bacteria isolated from medicinal plants are recognized valuable sources of novel bioactive compounds with various activities such as antimicrobial, anticancer, and antiviral. In this study, eleven bacterial endophytes were isolated from surface sterilized roots and leave tissues, of medicinal plant Dicoma anomala. The bacterial endophytes were identified by sequencing the 16S rRNA gene, and belong to five genera viz Bacillus, Staphylococcus, Stenotrophomonas, Enterobacter, and Pantoea. The dominant genera were Bacillus with five strains, Staphylococcus with two strains, and Stenotrophomonas with two strains. The crude extracts of seven selected bacterial endophytes indicated antimicrobial activity against five pathogenic strains Escherichia coli (ATCC 25922), Bacillus cereus (ATCC 10876), Staphylococcus aureus (NCTC 6571), Pseudomonas aeruginosa (ATCC 27853), and Klebsiella oxytoca (ATCC 13182), with significant inhibition concentration ranging from 0.312 mg/ml to 0.625 mg/ml. Finally, based on the data analysis of the crude extracts of the endophytes, we identified bioactive secondary metabolites with reported biological activities such as antimicrobial, anti-inflammatory, and antioxidant properties with biotechnological applications in medicine, agriculture, and other industries. This study reported for the first time bacterial endophytes associated with D. anomala, with antimicrobial activity against bacterial pathogens.