en Microbiology پژوهشي Research <div style="text-align: justify;"><span style="font-size:12px;"><span style="font-family:Times New Roman;"><b>Background:</b> The increasing prevalence of antimicrobial resistance has intensified the search for effective natural alternatives to synthetic antibiotics. Pomegranate (<i>Punica granatum</i>) peel, a widely available agricultural by-product, is known for its rich phytochemical composition. We aimed to quantify the in vitro antibacterial activity of pomegranate peel methanolic extract (PPME) against selected Gram-positive and Gram-negative bacteria and analyze their differential susceptibility.<br> <b>Methods:</b> Here, PPME was prepared using a Soxhlet apparatus, and its antibacterial efficacy was tested against <i>Staphylococcus aureus</i>, <i>Bacillus cereus</i>, <i>Escherichia coli</i>, and <i>Pseudomonas aeruginosa</i> via the agar well-diffusion method at the concentrations of 50, 100, 200, and 400 mg/mL. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth dilution technique. Data were analyzed employing one-way ANOVA.<b><span style="font-size:9.0pt"></span></b><br> <b>Results:</b> The PPME demonstrated notable dose-dependent antibacterial activity (p < 0.0001), especially against Gram-negative bacteria. <i>Escherichia coli</i> was the most sensitive bacterial strain, with the largest inhibition zone (27 mm) at 400 mg/mL and the lowest MIC (12.5 mg/mL) and MBC (25 mg/mL). Gram-positive bacteria were more resistant to PPME, for which <i>Bacillus cereus</i> showed the highest MIC (100 mg/mL) and MBC (200 mg/mL).<br> <b>Conclusion</b>: Pomegranate peel extract possesses potent antibacterial activity, exhibiting relatively stronger efficacy against Gram-negative pathogens, offering it a promising sustainable candidate for developing novel antibacterial agents, especially against resistant Gram-negative pathogenic strains. Further research is warranted to identify the active compounds of PPME and their mechanisms of action.</span></span><br> &nbsp;</div> Pomegranate, Anti-infective agents, Plant extracts, In vitro techniques, Microbial sensitivity tests 22 26 http://jcbr.goums.ac.ir/browse.php?a_code=A-10-615-2&slc_lang=en&sid=1 Aboalfazl Jafari-Sales a.jafari_1392@yahoo.com 10031947532846006595 10031947532846006595 No Department of Microbiology, Kaz.C., Islamic Azad University, Kazerun, Iran; Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran Aylin Golestani ayliin.golestanii@gmail.com 10031947532846006596 0009-0008-0886-9874 No Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran; Department of Cellular and Molecular Biology, Ta.C., Islamic Azad University, Tabriz, Iran Zahra Ghahremani zghahremani1380@gmail.com 10031947532846006597 0009-0002-9744-3707 No Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran; Department of Cellular and Molecular Biology, Ta.C., Islamic Azad University, Tabriz, Iran Mehrdad Pashazadeh Mehrdadpashazadeh85@gmail.com 10031947532846006598 0009-0005-0694-4592 Yes Infectious Diseases Research Center, TaMS.C., Islamic Azad University, Tabriz, Iran; Department of Laboratory Sciences and Microbiology, TaMS.C., Islamic Azad University, Tabriz, Iran