Antimicrobial Activity and Metabolomic Profiling of Secondary Metabolites From Endophytic Bacteria Associated With <i>Prunus africana</i>

Abstract

The rise of multidrug-resistant (MDR) pathogens and the overharvesting of medicinal plants such as Prunus africana highlight the need for sustainable discovery platforms. In this study, the antimicrobial potential of 23 endophytic bacterial strains isolated from P. africana was evaluated. Stronger activity against Gram-negative than Gram-positive pathogens was observed (p < 0.001). Multivariate analysis identified six endophytic bacterial isolates that exhibited antimicrobial activity against all six tested pathogens. These were Ralstonia pickettii, Bacillus altitudinis, Stenotrophomonas maltophilia, Bacillus paramycoides, Sphingopyxis chilensis, and Virgibacillus halophilus. Gas chromatography-mass spectrometry (GC-MS) profiling of their ethyl acetate extracts revealed 74 metabolites, including terpenoids (e.g., 5-cedranone), phenolic acids (e.g., 4-hydroxybenzoic acid), diketopiperazines, and fatty acids (hexadecanoic, octadecanoic acids). The metabolomes showed biosynthetic congruence with the host plant producing analogous antimicrobial compounds alongside unique metabolites. These findings demonstrate that P. africana endophytes represent a sustainable, cultivable source of antibacterial agents active against Gram-negative pathogens, addressing both drug discovery and conservation needs.