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Plant Science Today (PST)

Research Articles

Vol. 13 No. sp2 (2026): Recent Advances in Agriculture

Deciphering the antibacterial metabolome of endophytic Bacillus velezensis ER4 against Xanthomonas citri pv. malvacearum through integrated metabolomics

DOI
https://doi.org/10.14719/pst.13879
Submitted
28 January 2026
Published
10-06-2026

Abstract

Bacterial blight of cotton, caused by Xanthomonas citri pv. malvacearum, remains a major constraint to global cotton productivity. In the quest for sustainable and eco-friendly disease management strategies, endophytic Bacillus species were isolated, identified and evaluated for their antagonistic potential against this pathogen. A total of five endophytic Bacillus isolates namely ER4, EI3, ER5, EP5 and EI4 were obtained from internal root tissue of cotton and the molecular characterisation confirmed these isolates as Bacillus velezensis, Bacillus subtilis, Priestia megaterium, Priestia endophyticus and Bacillus tequilensis respectively. A cross-streak assay was performed to evaluate the efficacy of the above endophytes against X. citri pv. malvacearum. Among these, B. velezensis ER4 exhibited the highest inhibitory activity, producing a pronounced inhibition zone of 17 mm, indicative of potent diffusible antimicrobial metabolite production. To further assess volatile-mediated inhibition, an agar well diffusion assay employing volatile extracts of B. velezensis ER4 was conducted, demonstrating substantial suppression of pathogen growth. The strong antagonistic activity warranted an in-depth metabolomic investigation. Comprehensive metabolite profiling using gas chromatography–mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) revealed a total of 147 metabolites, grouped into 42 chemical classes and associated with 57 metabolic pathways, as determined through MetaboAnalyst 5.0, KEGG and HMDB analyses. Functional characterisation highlighted key roles in antimicrobial, antioxidant and plant growth-promoting activities. Notably, phenolic compounds, fatty acid derivatives, phthalates and pyrrolo[1,2-a] pyrazine analogues were identified as major bioactive components. These findings demonstrate the potential of B. velezensis ER4 as a promising biocontrol agent and provide a metabolomic foundation for the development of sustainable bioformulations for the effective management of bacterial blight in cotton cultivation.

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