title: Ethanol adaptation induces direct protection and cross-protection against freezing stress in Salmonella enterica serovar Enteritidis.
abstract: OBJECTIVE
  Salmonella enterica serovar Enteritidis (Salm. Enteritidis) encounters mild ethanol stress during its life cycle. However, adaptation to a stressful condition may affect bacterial resistance to subsequent stresses. Hence, this work was undertaken to investigate the influences of ethanol adaptation on stress tolerance of Salm. Enteritidis.
  
  
  RESULTS
  Salmonella Enteritidis was subjected to different ethanol adaptation treatments (2·5-10% ethanol for 1 h). Cellular morphology and tolerance to subsequent environmental stresses (15% ethanol, -20°C, 4°C, 50°C and 10% NaCl) were evaluated. It was found that 10% was the maximum ethanol concentration that allowed growth of the target bacteria. Ethanol adaptation did not cause cell-surface damage in Salm. Enteritidis as revealed by membrane permeability measurements and electron micrograph analysis. Salmonella Enteritidis adapted with 2·5-10% ethanol displayed an enhanced resistance to a 15%-ethanol challenge compared with an unchallenged control. The maximum ethanol resistance was observed when ethanol concentration used for ethanol adaptation was increased to 5·0%. Additionally, pre-adaptation to 5·0% ethanol cross-protected Salm. Enteritidis against -20°C, but not against 4°C, 50°C or 10% NaCl.
  
  
  CONCLUSIONS
  Ethanol adaptation provided Salm. Enteritidis direct protection from a high level ethanol challenge and cross-protection from freezing, but not other stresses tested (low temperature, high salinity or high temperature).
  
  
  CONCLUSIONS
  The results are valuable in developing adequate and efficient control measures for Salm. Enteritidis in foods.
authors.affiliation: MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: S
authors.initials: S
authors.lastname: He
authors.affiliation: MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: X
authors.initials: X
authors.lastname: Zhou
authors.affiliation: MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: C
authors.initials: C
authors.lastname: Shi
authors.affiliation: MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: X
authors.initials: X
authors.lastname: Shi
mesh_terms: D000064:Acclimatization / Q000187:drug effects; D000222:Adaptation, Physiological / Q000187:drug effects; D003080:Cold Temperature; D000431:Ethanol / Q000494:pharmacology*; D012477:Salmonella enteritidis / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*
chemical_list: D000431:Ethanol
keywords: Salmonella Enteritidis; cell membrane permeability; ethanol adaptation; ethanol tolerance; freezing tolerance