Listeria monocytogenes loss of cultivability on carrot is associated with the formation of mesosome-like structures
Journal Article
·
· International Journal of Food Microbiology
- USDA-ARS Beltsville Agricultural Research Center, Beltsville, MD (United States); Cornell University, Ithaca, NY (United States)
- USDA-ARS Beltsville Agricultural Research Center, Beltsville, MD (United States)
- University of Maryland, College Park, MD (United States); University of Georgia, Athens, GA (United States)
Raw carrot is known to have antimicrobial activity against Listeria monocytogenes, but the mechanism of action has not been fully elucidated. In this study, we examined carrot antilisterial activity against several strains of Listeria species (including L. grayi, L. innocua, L. seeligeri, and L. welshimeri) and L. monocytogenes. A representative strain of L. monocytogenes was subsequently used for further characterizing carrot antilisterial activity. Exposure to fresh-cut carrot for 15 min resulted in a similar loss of cultivability, ranging from 2.5 to 4.7 log units, across all Listeria strains evaluated. L. monocytogenes recovered from the fresh-cut surface of different raw carrots was 1.6 to 4.1 log lower than levels obtained from paired boiled carrot samples with abolished antilisterial activity. L. monocytogenes levels recovered from fresh-cut carrot were 2.8 to 3.1 log lower when enumerated by culture-dependent methods than by the culture-independent method of PMAxx-qPCR, a qPCR assay that is performed using DNA pre-treated to selectively sequester DNA from cells with injured membranes. These results suggested that L. monocytogenes loss of cultivability on fresh-cut carrot was not associated with a loss of L. monocytogenes cell membrane integrity and putative cell viability. Transmission electron microscopy imaging revealed that L. monocytogenes rapidly formed mesosome-like structures upon exposure to carrot fresh-cut surface but not upon exposure to boiled carrot surface, suggesting there may be an association between the formation of these mesosome-like structures and a loss of cultivability in L. monocytogenes. As a result, further research is necessary to conclude the causality of this association.
- Research Organization:
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0014664
- OSTI ID:
- 2425559
- Journal Information:
- International Journal of Food Microbiology, Journal Name: International Journal of Food Microbiology Journal Issue: C Vol. 390; ISSN 0168-1605
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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