Bacterial Endophytes of Prunus africana: Current Evidence, Antibacterial Metabolites, Biosynthetic Potential and Conservation Prospects

Abstract

Background: Antimicrobial resistance continues to reduce the effectiveness of existing antibiotics, creating an urgent need for new antibacterial compounds from alternative natural sources. Bacterial endophytes of medicinal plants are increasingly recognised as reservoirs of structurally diverse bioactive metabolites with potential pharmaceutical applications. Prunus africana, a medicinally important but conservation-sensitive Afromontane tree, remains poorly characterised with respect to its bacterial endophytes and their antibacterial metabolites, highlighting the need to evaluate their biosynthetic potential and possible relevance to conservation-aligned bioprospecting. Aims: This review examines the antimicrobial potential and biosynthetic diversity of endophytic bacteria associated with medicinal plants, with an emphasis on Prunus africana, and identifies research priorities for conservation-aligned bioprospecting. Methodology: A critical narrative review was conducted using literature published from 2000 to 2026 and retrieved from PubMed, Scopus, Web of Science, ScienceDirect, and Google Scholar. Citation tracing was used to identify additional relevant studies. The IUCN Red List, CITES, and Nagoya Protocol repository were consulted for conservation and regulatory information. Results: Bacterial endophytes associated with medicinal plants have been linked to lipopeptides, polyketides, bacteriocins, phenazines, diketopiperazines, phenolics, fatty acid derivatives, siderophores, organic acids, and VOCs, with reported MICs of 1.25–1600 µg/mL. At peak trade, P. africana bark extracts were valued at ~USD 220 million annually, while Kenya exported 200–250 t of dried bark per year. The species is currently listed as Vulnerable by the IUCN and in CITES Appendix II. However, direct experimental evidence for antibacterial metabolites produced by P. africana endophytes remains limited, although recent metabolomic work is beginning to address this gap. Conclusion: Further work should integrate culture-dependent and culture-independent methods, metabolite profiling, genome mining, and rigorous confirmation of microbial origin. Purification, biosynthetic gene cluster validation, mechanism-of-action studies, safety, and in vivo studies remain priorities. A five-layer conservation-aligned bioprospecting framework is proposed, linking endophyte isolation, bioactivity, metabolite identification, biosynthetic pathway characterisation, reproducible production, and assessment of potential reductions in wild bark harvesting.