Antimicrobial effects of essential oil vapors on Bacillus cereus on nutrient agar and iceberg lettuce

Hyewon Yang, Woorim Yeom, Jiwon Oh, Hoikyung Kim, Larry R. Beuchat, Jee Hoon Ryu

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1 Citation (Scopus)

Abstract

We investigated the antimicrobial effects of essential oil (EO) vapors individually and in combination against Bacillus cereus. In an initial study, EO vapors were generated from 95 commercially available EOs and their antimicrobial activities against B. cereus were tested. Five EO vapors (citronella, lemongrass, may chang, oregano, and thyme thymol) showed strong inhibitory activity. Next, we determined the minimal inhibitory concentrations (MICs) and minimal lethal concentrations (MLCs) of these EOs against B. cereus cultured on nutrient agar; values were 0.0781 μL/mL and >5 μL/mL, respectively. The synergistic antimicrobial activity of combinations between EO vapors on B. cereus were evaluated using a modified checkerboard assay. Oregano and thyme thymol EO vapors showed greatest synergism (fractional inhibitory concentration index: 0.5000 at a 1:1 vol ratio). Finally, we tested for antimicrobial properties of oregano and thyme thymol EO vapors against B. cereus on iceberg lettuce individually and in combination. The growth of B. cereus was inhibited by 0.0049–0.0098 μL/mL of EO vapors at concentrations 8- to 16-fold lower than that of MICs on nutrient agar. However, a combination of oregano and thyme thymol EO vapors did not have a synergistic lethal effect. Observations provide basic information for the development of decontamination treatments to inhibit the growth of B. cereus and perhaps other spore-forming bacteria on foods and food-contact surfaces using EO vapors.

Original languageEnglish
Article number102580
JournalFood Bioscience
Volume53
DOIs
Publication statusPublished - 2023 Jun

Bibliographical note

Funding Information:
This research has been supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) ( 2020R1F1A107507712 ).

Publisher Copyright:
© 2023

Keywords

  • Bacillus cereus
  • Iceberg lettuce
  • Oregano
  • Synergistic effect
  • Thyme thymol

ASJC Scopus subject areas

  • Food Science
  • Biochemistry

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