Selective toxcitiy screening of bacterial metabolite against probiotics

9Antimicrobial resistance (AMR) represents a growing global health crisis, necessitating the development of alternative antimicrobial strategies that effectively target pathogenic organisms while preserving beneficial microbiota. Conventional broad-spectrum antibiotics often lack selectivity, leading to disruption of probiotic populations and contributing to dysbiosis. This study aimed to evaluate the selective toxicity of a bacterial metabolite against pathogenic and non-pathogenic microorganisms, with a focus on its potential as a targeted antimicrobial agent. A broth microdilution assay was employed to determine the minimum inhibitory concentrations (MICs) of the metabolite using a 96-well microtiter plate. Five microorganisms were tested, including two pathogenic bacteria, Staphylococcus aureus and Pseudomonas aeruginosa, and three non-pathogenic organisms, Lactobacillus plantarum, Saccharomyces cerevisiae, and Candida albicans. Serial dilutions of the metabolite were prepared, and microbial growth was assessed using a tetrazolium chloride colorimetric indicator following 24-hour incubation at 37°C. Absorbance readings were obtained at 630 nm and analyzed to determine MIC values. The results demonstrated that the metabolite exhibited antimicrobial activity against both pathogenic organisms, with MIC values of 5.94. Notably, no inhibitory effects were observed against the non-pathogenic organisms at the concentrations tested. These findings indicate a degree of selective toxicity, with enhanced effectiveness against clinically relevant pathogens, including members of the ESKAPE group, while sparing beneficial or non-target microorganisms. In conclusion, the bacterial metabolite shows a non selective pattern of antimicrobial agent activity with no potential applications in combating antibiotic-resistant infections without compromising probiotic viability. Further studies are recommended to optimize testing conditions, expand the concentration range, and validate findings using standardized protocols to better assess its clinical applicability.