Journal of Bioscience and Biotechnology Discovery

Bacterial endophytes constitute an important but incompletely characterised component of medicinal-plant microbiomes and may contribute to plant–microbe interactions while providing a source of biologically active natural products. However, evidence across the field remains fragmented, with studies frequently emphasising bacterial isolation, taxonomic identification or preliminary antimicrobial screening without establishing clear relationships among microbial identity, biosynthetic capacity, metabolite production and biological function. This review critically synthesises current evidence on bacterial endophytes associated with medicinal plants, with particular emphasis on community diversity, culture-dependent and culture-independent approaches, molecular and phylogenetic identification, antimicrobial evaluation, metabolite characterisation, genome mining and activation of biosynthetic pathways. The available literature indicates that endophytic bacterial communities vary according to host species, tissue type, developmental stage, geography and methodological approach, while culture-dependent and sequencing-based methods each capture different components of the endophytic community. Although antimicrobial activity has been reported for numerous bacterial isolates and crude extracts, inhibition-zone measurements alone provide limited evidence of antimicrobial potency or therapeutic relevance. Stronger evidence is obtained through standardised quantitative susceptibility testing, activity-guided fractionation, chemical characterisation, and mechanistic validation. Similarly, detection of biosynthetic gene clusters indicates metabolic potential but does not establish metabolite expression or production. The review further identifies important gaps in African and Nigerian research, where medicinal plants and their associated bacterial communities remain comparatively underexplored. Irvingia gabonensis is discussed as an illustrative candidate for future integrated investigation rather than as a well-characterised bacterial-endophyte system. Future progress will depend on reproducible workflows that connect bacterial diversity and taxonomic identity with genome-based biosynthetic potential, metabolomic outputs, antimicrobial activity and subsequent chemical, safety and functional validation.