Comparative antimicrobial activity of clove and fennel essential oils against food borne pathogenic fungi and food spoilage bacteria
Antifungal and antibacterial activities of essential oils obtained from fennel seeds (Feoniculum vulgare Mill) and clove buds (Syzygium aromaticum) were studied by agar well dilution technique. Both essential oils (EOs) from fennel and clove exhibited pronounced and varying degrees of growth inhibition against fungal (86 to 39%) and bacterial pathogens (42 to 20%). Fennel oil depicted significant and greater fungitoxicity in case of three fungal strains Alternaria alternate (7.7, 3.8 cm) Fusarium oxysporum (5.9, 4.1 cm) and Aspergillus flavus (4.5, 3.7 cm) except two Aspergillus strains, Aspergillus acculeatus and Apergillus fumigatus where clove oil showed greater inhibition zone (5.5, 5.9 cm) (3.5, 3.7 cm) respectively. A. alternate was found to be most sensitive strain, which growth was suppressed up to 86% by fennel seeds oil. Bactericidal activity of culinary spices was evaluated against five food spoilage bacteria namely: Pseudomonas syringae, Bacillus subtilis, Escherichia coli, Staphylococcus sp., and Aeromicrobium erythreum. Fennel oil was found fairly active against bacterial strains as compared to clove oil with highest antibacterial activity against Gram positive bacteria Bacillus subtilis (3.8 cm) and least against Gram negative bacteria E. coli (2.2 cm). The summarizing results from the present investigation showed that fennel seeds oil is a relatively stronger antimicrobial agent against broad range of pathogens as compared to clove oil, except in case of certain Aspergillus strains and E. coli.
Key words: Food spoilage, anti-bacterial, pathogenic fungi, clove, fennel, essential oil.