Antibacterial Activity of Stigmatellin Y from Marine Bacillus amyloliquefaciens Against MDR Pseudomonas aeruginosa

Introduction: Hospital-acquired infections caused by Pseudomonas aeruginosa strains frequently exhibit resistance to both monotherapy and combination therapy with antibiotics because of acquired and intrinsic resistance mechanisms. Therefore, there is an urgent need for novel and potent antibiotics to treat infections caused by multidrug-resistant (MDR) P. aeruginosa. Bioactive compounds from marine Bacillus species have the potential to inhibit the growth of MDR P. aeruginosa. Methods: In the present investigation, a Bacillus species was isolated from seawater using Zobell Marine Agar. The isolate was identified by morphological, biochemical, and ۱۶S rRNA gene sequencing analyses. Ethyl acetate was used to extract extracellular bioactive secondary metabolites from the cell-free supernatant of the isolated strain. Column chromatography (silica gel, ۱۰۰–۲۰۰ mesh) was employed to further fractionate the crude extract, and the agar well diffusion method was used to assess antibacterial activity against MDR P. aeruginosa. The bioactive fraction F۱ was putatively annotated using ultra-high-performance liquid chromatography–ultraviolet–mass spectrometry (UHPLC-UV-MS). Results: The marine bacterial isolate was identified as Bacillus amyloliquefaciens. The crude extract and its purified fraction F۱ inhibited the growth of MDR P. aeruginosa. The column chromatography–purified bioactive fraction F۱ showed zones of inhibition ranging from ۱۵.۰ to ۱۶.۷ mm against MDR P. aeruginosa. UHPLC-UV-MS analysis putatively annotated bioactive fraction F۱ as stigmatellin Y, exhibiting a retention time of ۲۸.۵۰ min and a mass-to-charge ratio (m/z) of ۵۰۷.۲۷۲۵ ([M+Na]⁺. Conclusion: This marine B. amyloliquefaciens strain produces the potent compound stigmatellin Y, which exhibits activity against MDR P. aeruginosa. This finding highlights the strain's potential as a source of novel therapeutic agents.

کلیدواژه ها:

Multidrug-resistant Pseudomonas aeruginosa ، Stigmatellin Y ، Marine Bacillus amyloliquefaciens ، UHPLC-UV-MS