Broad-Spectrum Antimicrobial Activity of Thymus Zygis Essential Oil Against Various Microorganisms

In this study, the antimicrobial effect of the T. zygis essential oil (EO) was investigated on 68 bacterial and two yeast isolates belonging to 20 different families, including foodborne, ready-to-eat food, aquatic, and collection strains that are important for food safety and aquaculture. First, the chemical composition of the oil was analyzed using GC-MS to better understand its potential bioactivity. The major components of the T. zygis EO were identified as thymol (38.82%), β-cymene (21.66%), γ-terpinene (6.51%), carvacrol (6.36%) and linalool (6.25%) and the total of these components constituted 79.6% of the essential oil. In terms of antimicrobial activity, the disk diffusion test revealed inhibition in 66 out of 70 tested strains, with strong inhibition observed in 62 strains, moderate inhibition in four, and no inhibition in the remaining four. It showed strong antimicrobial activity against species known to be foodborne and fish pathogens such as Aeromonas hydrophila, Aeromonas salmonicida, Escherichia coli, Pseudomonas putida, Salmonella enterica, Staphylococcus aureus, Streptococcus iniae, Klebsiella pneumoniae, Edwardsiella tarda, Lactococcus garvieae, Yersinia ruckeri, Vibrio parahaemolyticus, Vibrio anguillarum, and Vibrio gigantis. In addition, it has been determined that the T. zygis EO has strong antifungal activity against yeast species such as Candida albicans and Saccharomyces cerevisiae. Antimicrobial activity levels were attributed to the high levels of phenolic components, especially thymol. In conclusion, this study has shown that the essential oil derived from T. zygis exhibits broad-spectrum antimicrobial activity and an effective natural bioprotective agent for both Gram-positive and Gram-negative bacteria and yeast species. In addition, this study provides an original contribution to the literature through a comprehensive evaluation of its effect on microorganisms isolated from various sources. Future studies should focus on the stability, sensory properties, and mechanisms of action of the T. zygis essential oil, particularly in diverse seafood applications.