Impact of Growth Temperature and Agar Versus Liquid Media on Freeze–Thaw Tolerance ofYersinia enterocolitica

Abstract

Yersinia enterocolitica is a foodborne pathogen well known for its ability to grow at low temperatures. Recent studies with another psychrotrophic foodborne pathogen, Listeria monocytogenes, revealed that temperature of growth had pronounced impact on survival following repeated freezing and thawing (cryotolerance). Listerial cryotolerance was significantly more pronounced when bacteria were grown at 37 degrees C than following growth at either 4 degrees C or 25 degrees C. However, it is not known whether such impact of growth temperature is a general adaptation shared with other foodborne pathogens. In this study, we investigated the impact of growth temperature (4 degrees C, 25 degrees C, and 37 degrees C) on cryotolerance of Y. enterocolitica. In strong contrast to findings previously obtained with Listeria spp., cryotolerance of Y. enterocolitica was impaired following growth in liquid media at 37 degrees C, with cell concentration dropping to undetectable levels (<10(1) colony forming unit/mL) following as few as six freeze-thaw cycles. On the other hand, when the bacteria were grown at 4 degrees C, cryotolerance was significantly higher (p < 0.05), and substantial survival was maintained even after 18 cycles (2-5 log reduction, depending on strain). Enhanced cryotolerance was also observed with cultures grown at 25 degrees C. Bacteria grown at 37 degrees C on agar were significantly more cryotolerant than following growth at 37 degrees C in liquid media (p < 0.05). The data suggest species-specific impact of growth temperature and liquid versus agar medium on cryotolerance of cold-tolerant bacteria.

Guidance on date marking and related food information: part 2 (food information)

“…Repeated freeze-thaw cycles generally lead to greater inactivation and lower microbial concentrations, but pathogens may survive, i.e. be cryotolerant; defined as the ability to survive repeated cycles of freeze thawing (Azizoglu and Kathariou, 2010). Actively growing bacteria are more susceptible to freeze-thaw inactivation than stationary phase cells (e.g.…”

Editorial: The Pathogenic Yersiniae–Advances in the Understanding of Physiology and Virulence, Second Edition

“…Enteropathogenic Yersinia are foodborne pathogens. Therefore it comes as no surprise that they thrive at refrigeration temperatures (Brocklehurst and Lund, 1990; Goverde et al, 1994; Azizoglu and Kathariou, 2010; Keto-Timonen et al, 2018), and in this environment even remain primed for infection (Asadishad et al, 2013). To understand the molecular mechanisms by which psychotropic Yersinia thrive in cold environments may give rise to strategies by which growth can be restricted, and this would be a strategically important preventative measure for the food processing industry.…”

Isolate Specific Cold Response of Yersinia enterocolitica in Transcriptional, Proteomic, and Membrane Physiological Changes

“…Yersinia enterocolitica is capable of growing at temperatures approaching and even below 0 • C (Tudor et al, 2008;Divya and Varadaraj, 2013). Therefore, even refrigeration temperatures (0-4 • C) can allow significant bacterial growth over time.…”

“…Therefore, even refrigeration temperatures (0-4 • C) can allow significant bacterial growth over time. Several studies have reported growth of Y. enterocolitica in food products stored at refrigeration temperatures: e.g., on raw beef, with increased cell counts of up to 2 log CFU/ml within 4 days (Tudor et al, 2008) and in pasteurized milk, reaching levels of 5-7 log CFU/ml after 7 days (with an initial inoculum of 1-3 log CFU/ml) (Amin and Draughon, 1987).…”