Solid- and Vapor-Phase Antimicrobial Activities of Six Essential Oils:  Susceptibility of Selected Foodborne Bacterial and Fungal Strains

Abstract

The antimicrobial activity of essential oils (EOs) of cinnamon (Cinnamon zeylanicum), clove (Syzygium aromaticum), basil (Ocimum basillicum), rosemary (Rosmarinus officinalis), dill (Anethum graveolens), and ginger (Zingiber officinalis) was evaluated over a range of concentrations in two types of contact tests (solid and vapor diffusion). The EOs were tested against an array of four Gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, and Listeria monocytogenes), four Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Salmonella choleraesuis, and Pseudomonas aeruginosa), and three fungi (a yeast, Candida albicans, and two molds, Penicillium islandicum and Aspergillus flavus). The rationale for this work was to test the possibility of creating a protective atmosphere by using natural compounds that could extend the shelf life of packaged foodstuffs while minimizing organoleptic alterations. In the solid diffusion tests, cinnamon and clove gave the strongest (and very similar) inhibition, followed by basil and rosemary, with dill and ginger giving the weakest inhibition. The fungi were the most sensitive microorganisms, followed by the Gram-positive bacterial strains. The Gram-negative strain P. aeruginosa was the least inhibited. The composition of the atmosphere generated by the EOs, and their minimum inhibitory concentrations (MICs), were determined using a disk volatilization method, in which no inhibition from rosemary or basil was observed. Cinnamon and clove, once again, gave similar results for every microorganism. As a general rule, MIC (fungi) << MIC (bacteria) with no clear differences between Gram-positive or -negative strains except for P. aeruginosa, which was not inhibited by any of the EOs in the vapor phase. The atmosphere generated from the EOs was analyzed by means of solid-phase microextraction combined with gas chromatography-ion trap mass spectrometry. Differences among the volatiles in the EOs, which may be responsible for the differences in their antimicrobial performances, were found.

Essential oil of &lt;i&gt;Thymus vulgaris&lt;/i&gt; L. and &lt;i&gt;Rosmarinus officinalis&lt;/i&gt; L.: Gas chromatography-mass spectrometry analysis, cytotoxicity and antioxidant properties and antibacterial activities against foodborne pathogens

“…Both essential oils showed a significant antibacterial activity against Gram positive as well as Gram negative bacteria that confirms previous findings [17,41,46]. Thyme essential oil exhibited a higher anti-microbial activity than that of rosemary essential oil, which was similar to the results of the sensitivity test ( Table 2).…”

Versatile and Synergistic Potential of Eugenol: A Review

“…Wie et al (1997) reported that eugenol reversed neuronal excitotoxic or oxidative injury and had protective effect against N-methyl-D-aspartate-induced neurotoxicity. [22][23][24][25][26][27][28][29]. Eugenol induced cell lysis of Gram-negative and Gram-positive bacteria by damaging the cell wall and membrane caused leakage of protein and lipid contents (Figure 4) [29].…”

Activity of Some Disinfectants, Detergents and Essential Oils on Growth of the yeast Candida albicans

“…The clove oil has beneficial analgesic, antiseptic, and anesthetic effects [20] and worldwide used in dental medicine. Fungicidal activities of clove oil against yeasts are reported in previous studies [21], and human pathogenic fungi [22]. The study aimed to estimate the fungicidal activity of some disinfectants and plant oils and to know the effect of combination between them at low concentration on growth of Candida albicans.…”