Microbial alkaloids are a class of bioactive secondary metabolites with significant therapeutic potential, including antimicrobial and anticancer properties. This study aimed to isolate, purify, and characterize alkaloids from cultivable bacteria obtained from yogurt and evaluate their biological activities. Three bacterial isolates (YG-1, YG-2, and YG-3) were recovered, and YG-2 was identified as Lacticaseibacillus casei based on colony morphology, Gram staining, and biochemical profiling. Crude extracts were obtained through solvent extraction and fractionated using column chromatography. TLC analysis revealed distinct alkaloid spots, while FTIR and UV–Vis spectroscopy confirmed the presence of functional groups characteristic of alkaloids. The purified fractions exhibited notable antimicrobial activity against both Gram-positive (Staphylococcus aureus, Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as antifungal activity against Candida albicans and Aspergillus niger. The results demonstrate that yogurt-derived L. casei can serve as a novel source of bioactive alkaloids with potential therapeutic applications. This study underscores the significance of food-derived probiotics as a safe and sustainable resource for natural drug discovery
