The conducted study compares the phytochemical and the antimicrobial potential of four varieties of Brassica napus seed oils. The plant seeds were cultivated during the winter growing season. Soxhlet extractor and Gas Chromatography-Mass Spectrometer (GC-MS) were used for essential oil analysis. The micro broth dilution
assay was applied to test the antimicrobial potential (MIC: Minimum inhibitory concentration, MBC: Minimum bactericidal concentration) of the extracted essential oils against different bacterial strains. A total of 56 phytochemicals were found, including 23 and 25 compounds in the oils of Pactol and Rapifera seed varieties,
respectively, and 21 compounds in each of Bacara and Rally seed oils. Oleic acid constituted about 35.79 %, 15.62%, 7%, and 2.41 % for Rally, Bacara, Rapifera, and Pactol seed oils, respectively. Gram-positive bacteria, Streptococcus pyogenes and Streptococcus agalactiae, showed lower resistance potentials (MIC= 0.78%, 3.125%
respectively) (MBC=1.36%, 6.25% respectively) to the essential oils compared with Staphylococcus aureus. Escherichia coli showed higher sensitivity (6.25% and 12.5% for MIC and MBC, respectively) than Klebsiella pneumonia and Pseudomonas aeruginosa to the B. napus seed oils. Gram-positive bacteria were
more sensitive to the tested essential oils than Gram-negative bacteria. Overall, four different seed varieties have important chemicals and fatty acids. Oleic acid was the most common carboxylic acid (fatty acid) and 2,4-decadienal with hexanal were the most prevalent aldehydes in four seed oils. Tested B. napus seed essential oils
showed antimicrobial activities against various Gram-positive and negative bacteria and Candida albicans, with Pactol seed oils exerting the highest activity.