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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #407085
Research Project: Elucidating the Factors that Determine the Ecology of Human Pathogens in Foods

Location: Produce Safety and Microbiology Research

Title: The stress response of Listeria monocytogenes inoculated on fresh apples exposed to gaseous chlorine dioxide

Author
item GUAN, JIEWEN - Washington State University
item Lacombe, Alison
item RANE, BHARGAVI - Washington State University
item Van Blair, Jared
item Zhang, Yujie
item TANG, JUMING - Washington State University
item SABLANI, SHYAM - Washington State University
item Wu, Vivian

Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2024
Publication Date: 5/7/2024
Citation: Guan, J., Lacombe, A.C., Rane, B., Van Blair, J.B., Zhang, Y., Tang, J., Sablani, S., Wu, V.C. 2024. The stress response of Listeria monocytogenes inoculated on fresh apples exposed to gaseous chlorine dioxide. Journal of Food Safety. 44(3) Article. e13126. https://doi.org/10.1111/jfs.13126.
DOI: https://doi.org/10.1111/jfs.13126

Interpretive Summary: Listeria monocytogenes, the species of pathogenic bacteria that causes listeriosis, has been responsible for multiple apple recalls. A listeriosis outbreak in caramel apples in 2014 led to illnesses and a new focus on risk management in packing houses and cold storage. The most crucial tool for packing and processing facilities is good sanitation practices, especially in the niches where Listeria has been known to gather. Gaseous ClO2 is a potential strategy to improve food safety during cold storage because it has strong antimicrobial properties. However, little is known about the mechanism of action of ClO2 against Listeria. This experiment reveals that ClO2 can inhibit the virulence of Listeria by downregulating the genes that make the pathogen toxin. This information is essential because it demonstrates that Listeria is potentially less virulent following ClO2 treatment. Apple processors can use this information during cold storage to improve food safety problems.

Technical Abstract: Fresh apples are vulnerable to Listeria contamination during cold storage. Gaseous chlorine dioxide (ClO2) has been studied to control Listeria on a lab scale, as well as pilot-scale and semi-industrial scale. In this study, the stress response of Listeria monocytogenes (L. monocytogenes) on apples exposed to gaseous ClO2 was investigated. Bacteria were spot inoculated on the surfaces of sterile apples. Then the inoculated apples were exposed to 10 ug precursor/g apple low dose of gaseous ClO2 for 1 h at ambient temperature in order to examine gene expression. The RNA of L. monocytogenes on apples was extracted from control and treated samples after treatment. Then the purified RNA was used for Real-Time quantitative polymerase chain reaction (RT-qPCR) to analyze the transcriptional changes in two relevant virulence (hly) and stress (clpC) genes of L. monocytogenes. hly and clpC were downregulated when normalized to the housekeeping gene rpoB during the stress condition of gaseous ClO2. Our result indicates that gaseous ClO2 treatment can decrease virulence and potentially reduce the stress feedback of L. monocytogenes. This study contributes to understanding the antimicrobial mechanism of gaseous ClO2 on fresh apples. Ultimately, the antimicrobial mechanism of gaseous ClO2 may help to find an optimal condition for effective decontamination of apples and subsequently enhance the safety of fresh apples.