The fate of cold‐stressed or tetracycline‐resistantVibrio spp. in precooked shrimp during frozen storage

Abstract

We compared the fate of cold‐stressed (CS) or tetracycline‐resistant (TR) Vibrio parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae in precooked shrimp during frozen storage. The recovery ability of viable but nonculturable (VBNC) Vibrio cells was compared at 25°C. Each suspension of nonstressed (NS), CS, or TR Vibrio cells inoculated into cooked shrimps were subjected to frozen storage at −20°C or three freeze–thaw cycles. CS and TR cells were more rapidly converted to VBNC state than NS cells. Most of VBNC Vibrio cells were observed as viable cells after frozen storage. Although there were differences in the recovery extent of cells depending on the types of stress and strain, VBNC cells were resuscitated at 25°C. The most resistant to tetracycline and the lowest injury rate were observed in V. cholerae cells during frozen storage.

Impact of Freeze–Thaw Cycles on Die-Off of E. coli and Intestinal Enterococci in Deer and Dairy Faeces: Implications for Landscape Contamination of Watercourses

“…For example, the magnitude of population decline experienced by E. coli in dairy faeces exposed to the −8 °C F–T cycle was more pronounced than when exposed to a constant 0 °C. This difference was only evident for the F–T regime at the lower temperature and likely reflects the greater damage inflicted to cell membranes and walls given that repeated F–T cycles would encourage recrystallisation and therefore promote the growth of larger ice crystals relative to those developing at a constant 0 °C [ 31 ]. The difference observed between control and F–T treatments was not apparent in the data for deer faeces, suggesting that the dairy faeces offered greater protection to FIOs at a constant of 0 °C, whereas the detrimental impacts of ice crystal formation appeared to have occurred to a similar extent under both control and F–T treatments for deer faecal pellets.…”