Determination of minimum inhibitory and lethal concentrations of two lactic acid bacteria Lactiplantibacillus plantarum reveals strain-specific antibiotic resistance.

Lactic acid bacteria (LAB) are widely used as probiotics and in fermented foods, yet their antibiotic resistance profiles remain under-characterized. This study evaluates the antibiotic resistance profiles of two Lactiplantibacillus plantarum ( L. plantarum ) strains, LpWF (isolated from Drosophila melanogaster ) and Lp39 (from cabbage), using broth microdilution methods. Minimum inhibitory concentrations (MICs) and minimum lethal concentrations (MLCs) were determined for six antibiotics. Strain-specific differences were found in MICs for kanamycin, neomycin, and geneticin, while ampicillin and chloramphenicol MICs were similar. Both strains exhibited intrinsic resistance to vancomycin. These findings contribute to efforts to characterize the LAB resistome and inform probiotic strain selection.