In vivogene expression of cold shock and other stress-related genes inVibrio vulnificusduring shellstock temperature control conditions in oysters

Abstract

Aims: To determine Vibrio vulnificus response to shellstock refrigeration conditions while the bacterium was embedded in oysters (in vivo). Methods and Results: Depurated oysters were artificially inoculated with V. vulnificus. Several cold‐shock conditions were examined according to the National Sanitation Shellfish Program guidelines. Culturability of cells along the refrigeration period was measured using specific colony dot‐blot. Gene expression of putative cold‐shock genes (csp1, csp3, csp4 and csp5) as well as three stress‐related genes (rpoS, oxyR and katG) was determined by reverse transcriptase polymerase chain reaction. Vibrio vulnificus exhibited a decline in cell viability after cold shock but a cold adaptation response was observed when oysters were kept at suboptimal (15°C) temperatures. 16SrRNA, and rpoS genes were constitutively expressed while expression of csp genes varied among strains and time points. Conclusions: Vibrio vulnificus culturability was reduced after oysters were subjected to shellstock refrigeration conditions. When V. vulnificus was allowed to acclimate to cold temperatures, its survival after cold shock was higher. None of the cold shock genes analysed behaved as csp type I genes. Significance and Impact of the Study: A model for artificially inoculated specific strains of V. vulnificus into oysters has been established. For the first time, V. vulnficus gene expression was assessed with the pathogen embedded in oysters.

Comparative Survival and the Cold-Induced Gene Expression of Pathogenic and Nonpathogenic Vibrio Parahaemolyticus from Tropical Eastern Oysters during Cold Storage

“…There is evidence that V. vulnificus survival and tolerance at cold temperature could be due to the expression of cold adaptive genes as the csp genes, encoding for putative cold shock proteins, which were differentially expressed in response to in vivo cold shock. Furthermore, in that study the V. vulnificus response to cold shock (15 to 4 • C) in oysters was similar to the response in vitro conditions [42].…”

“…To eliminate the natural Vibrio vulnificus cells that were present, Limthammahisorn et al [42] depurated oysters with autoclaved seawater at 25 • C prior to the inoculation of clinical and environmental V. vulnificus strains to determine the response to cold shock. Their results indicated that the V. vulnificus response to suboptimal temperatures in oysters was similar to that under in vitro conditions.…”

Managing the risk of Vibrio parahaemolyticus infections associated with oyster consumption: A review

“…(2017) reported that oyster samples that were immediately refrigerated (at a temperature of <7 °C) had a lower concentration of V. parahaemolyticus than the samples that were not refrigerated. Vibrio parahaemolyticus could not grow, was injured, or at least inactivated at temperatures of <10 °C (Cook & Ruple, 1989; Gooch et al., 2002; Limthammahisorn, Brady, & Arias, 2009). Other studies have shown that immediate refrigeration of oysters reduced the concentration of this pathogen by approximately one order of magnitude (Cook & Ruple, 1989, 1992; Jones et al., 2017; Limthammahisorn et al., 2009).…”

“…Vibrio parahaemolyticus could not grow, was injured, or at least inactivated at temperatures of <10 °C (Cook & Ruple, 1989; Gooch et al., 2002; Limthammahisorn, Brady, & Arias, 2009). Other studies have shown that immediate refrigeration of oysters reduced the concentration of this pathogen by approximately one order of magnitude (Cook & Ruple, 1989, 1992; Jones et al., 2017; Limthammahisorn et al., 2009). These results showed that refrigerating oysters as soon as possible after harvest is critical in preventing the rapid growth of V. parahaemolyticus in oysters.…”

Influence of oxyR on Growth, Biofilm Formation, and Mobility of Vibrio parahaemolyticus

“…The effect of oxyR on the survival of bacteria and on their viable but nonculturable state has been investigated in Vibrio vulnificus (20)(21)(22) and in Vibrio harveyi (23). The oxyR deletion mutant of Vibrio cholerae is sensitive to H 2 O 2 , causes defective growth in a rich medium, and weakens intestinal colonization in zebrafish (24).…”