Humboldt Journal of Microbiology


S. marcescens is a gram-negative, facultatively anaerobic bacterium that is particularly aggressive in its growing capability. It is a concern in medical fields as well as home environments due to its resistance to most antibiotics, high mortality rate, and easy ability to colonize on soap and other fatty substances. Although testing of natural cleansers such as lemon juice, vinegar, and ammonia has been done on S. marcescens and essential oil efficacy has been tested on Escherichia coli and Staphylococcus aureus, no literature has been published on the effect of essential oils on S. marcescens growth. The purpose of this experiment therefore was to test the efficiency of essential oils in inhibiting the growth of this bacterium. Using Kirby-Bauer Assay and Minimum Inhibitory Concentration testing we compared the effectiveness of different harsh cleaners such as Lysol®, with peppermint and helichrysum essential oils. Although few significant values were obtained, noticeable zones of inhibition were seen, especially for peppermint oil. Based on this finding, further research should be done exploring this potency of peppermint and other essential oils on S. marcescens.

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