Cross-protective effect of acid-adaptedSalmonella entericaon resistance to lethal acid and cold stress conditions

Abstract

Aims: To evaluate the cross‐protected Salmonella enterica cells under acid and cold stress conditions. Methods and Results: The acid‐adapted S. enterica cells were exposed to pH 4·0 at 4 and 20°C. Recovery of sublethally injured cells was estimated by the difference between the counts obtained on trypticase soy agar (TSA) and xylose lysine desoxycholate (XLD) agar. The survival curves of nonadapted and acid‐adapted S. enterica cells at pH 4·0 were fitted with Weibull distribution model. The recovery behaviour of injured S. enterica cells was estimated by the modified Gompertz parameters. Acid‐adapted S. enterica were more resistant to subsequent acid shock than the nonadapted cells. The numbers of nonadapted S. enterica cells were decreased by 4·57 and 7·55 log CFU ml−1 at 4 and 20°C after 12‐day acid challenge, respectively. The acid adaptation induced cross‐protection and viable nonculturable (VBNC) state against low acid and cold stresses. The 7‐h adaptation showed the least recovery of injured cells. Conclusion: The results suggest that acid‐adapted S. enterica cells induced acid tolerance response and VBNC state. Significance and Impact of the Study: These results provide useful information for understanding the induction of cross‐protected and VBNC pathogens under various stresses, which might be needed in designing new food preservation strategies.

Resistance and survival strategies of Salmonella enterica to environmental stresses

“…The development of acid tolerance/resistance in S. enterica is very complex and highly influenced by stage of growth (e.g., exponential-phase versus stationaryphase), growth temperature, the mode of environmental acidification (e.g., the presence of organic or fatty acids versus inorganic acids) and/or the presence of certain amino acids (e.g., arginine, lysine) (Álvarez-Ordóñez, Fernández, Bernardo & López, 2010a, 2010b; Audia, Webb, & Foster, 2001;Karatzas et al, 2008;Kieboom & Abee, 2006;Kwon & Ricke, 1998;Xu, Lee, & Ahn, 2008).…”

Growth and Virulence Properties of Biofilm-FormingSalmonellaentericaSerovar Typhimurium under Different Acidic Conditions

“…The viability of S. Typhimurium, which is initially adapted to mild acidic conditions (pH 4.5 to 5.8), can be subsequently enhanced under lethal acidic conditions (pH 3.0) by induction of acid shock proteins (ASPs) (3). Moreover, the acid-adapted cells can also provide multiple tolerance toward various stresses, such as heat, cold, osmotic, and oxidative stresses, known as the crossprotection phenomenon (22,36,57). Since organic acids such as acetic and lactic acids have been widely used as food preservatives for extending shelf life, many researchers have raised concerns over acid tolerance response (ATR) in the virulence of food-borne pathogens (24,48).…”

Acid and low temperature treatments on Salmonella Enteritidis inoculated in pork and its subsequent survival in simulated gastric fluid

“…In this research, prior acid treatment of pork did not affect the survival rate of both S. Enteritidis CCS3 and ATCC 13076 during storage at refrigeration or freezing temperatures, indicating that there was no cross-resistance. Conversely, cross-resistance was observed for S. Enteritidis previously exposed to acidic conditions in culture medium (XU et al, 2008) and for Salmonella Typhimurium in fermented dairy products (SHEN et al, 2007) at low temperatures. This phenomenon investigated food pathogens acquiring resistance to adverse conditions after moderate stress conditions during food processing.…”