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BackgroundNowadays, essential oils are recognized as safe substances and can be used as antibacterial additives. Salvia sclarea is one of the most important aromatic plants cultivated world-wide as a source of essential oils. In addition to being flavoring foods, Salvia sclarea essential oil can also act as antimicrobials and preservatives against food spoilage. Understanding more about the antibacterial performance and possible mechanism of Salvia sclarea essential oil will be helpful for its application in the future. But so far few related researches have been reported.ResultsIn our study, Salvia sclarea oil showed obvious antibacterial activity against all tested bacterial strains. Minimum inhibitory concentration (MIC) and minimum bactericide concentration (MBC) of seven pathogens were 0.05 and 0.1 % respectively. In addition, Salvia sclarea oil also exhibited a significant inhibitory effect on the growth of Escherichia coli (E. coli) in phosphate buffer saline (PBS) and meats. After treated with Salvia sclarea oil, Scanning Electron Microscope (SEM) images can clearly see the damage of cell membrane; the intracellular ATP concentrations of E. coli and S. aureus reduced 98.27 and 69.61 % respectively, compared to the control groups; the nuclear DNA content of E. coli and S. aureus was significantly reduced to 48.32 and 50.77 % respectively. In addition, there was massive leakage of cellular material when E. coli and S. aureus were exposed to Salvia sclarea oil.Conclusions Salvia sclarea essential oil damaged the cell membrane and changed the cell membrane permeability, leading to the release of some cytoplasm such as macromolecular substances, ATP and DNA. In general, the antimicrobial action of Salvia sclarea essential oil is not only attributable to a unique pathway, but also involves a series of events both on the cell surface and within the cytoplasm. Therefore, more experiments need to be done to fully understand the antimicrobial mechanism of Salvia sclarea essential oil.

In the present paper, the chemical composition of Helichrysum italicum oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Neryl acetate (32.65%) was the main component. The minimum inhibitory concentration and minimum bactericidal concentration of H. italicum oil against several bacteria were evaluated. The results showed that H. italicum oil exhibited high antibacterial activity against all of the bacteria tested. In addition, H. italicum oil also displayed a significant effect on inhibiting the growth rate of surviving Escherichia coli and Staphylococcus aureus in vitro and on vegetables. Meanwhile, addition of H. italicum oil to vegetable exerted a bacteriostatic effect. Besides, the mechanisms of the antimicrobial action of H. italicum oil to E. coli and S. aureus were concluded as that H. italicum oil could disrupt the cell membrane integrity, leading to the losses of intracellular constituents, such as the 260 nm absorbing materials, DNA and ATP. PRACTICAL APPLICATIONSAs a kind of natural, safe spice, Helichrysum italicum oil has been proven to be a good antibacterial agent against a wide range of bacteria at a low concentration and short incubation time. Especially, H. italicum oil exhibits a significant bacteriostatic effect in vegetables. Based on the results, we believe that H. italicum oil can be applied in vegetable processing and preservation.

In this study, the antibacterial activities of nutmeg oil and nutmeg oil encapsulated in liposome were evaluated.

The aim of this study is to investigate the antibacterial characteristics and mechanisms of nutmeg oil. In this paper, 54 chemical compositions of nutmeg oil were analyzed by gas chromatography–mass spectrometry (GC–MS). The major volatile components of nutmeg oil were sabinene (39.12%) and alpha‐pinene (11.96%). In addition, nutmeg oil showed significant antibacterial activity, minimum inhibitory concentration, and minimum bactericide concentration of seven pathogens are 0.05 and 0.1%, respectively, and the nutmeg oil also had a significant effect on inhibiting the growth of Escherichia coli and Staphyloccocus aureus in phosphate buffer saline and pork. Subsequently, in order to reveal the possible antibacterial mechanisms of nutmeg oil against pathogens, the damage of cell membrane was observed by scanning electron microscopy, the loss of 260 nm absorbing material was tested by ultraviolet spectrophotometer, and the cellular adenosine triphosphate concentrations were measured by the Surface Hygiene Test Kit. Finally, the decrease of nucleic acid was evaluated by inverted fluorescence microscope. These results indicated that the antibacterial mechanisms of the nutmeg oil against bacteria might be interpreted as disrupting cell membrane and inhibiting synthesis of DNA. Practical Applications As a natural and safe antibacterial agent, nutmeg oil exhibited good antimicrobial activity against a wide range of spoilage and pathogenic bacteria. Meanwhile, the antimicrobial activity of nutmeg oil has been proved on pork. Based on the results, we believe that nutmeg oil can be applied in meat storage and preservation.