Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2005-12-26
pubmed:abstractText
Escherichia coli O157:H7 (HEC), E. coli O157:H7 rpoS mutant (HEC-RM), and nonpathogenic E. coli (NPEC) were step-wise adapted to trisodium phosphate (TSP) by incubation in broths of increasing concentration, from 0% to 0.6%, at 37 degrees C for 24 h. After incubation at each concentration, each population was examined for acid resistance (D value) in simulated gastric fluid of pH 1.5, cell envelope membrane lipid composition, and intracellular and extracellular verotoxin concentrations. The ratio of cis-vaccenic acid (18:1omega7c) to palmitic acid (16:0) increased, indicating increased membrane fluidity with increasing TSP concentration up to 0.4%, but decreased at 0.6%. HEC and HEC-RM adapted at 0.4% TSP had the highest verotoxin concentrations of 1805 and 1879 ng/ml, respectively. In addition, with HEC the ratio of extracellular to intracellular verotoxin concentration decreased at higher TSP concentrations. In contrast, the ratio for HEC-RM increased at 0.4% TSP. HEC adapted to 0.4% TSP had the greatest survival in gastric fluid (58 min D value) among all treatments. For HEC, the increase in membrane fluidity was associated with increased acid resistance and extracellular verotoxin concentration for cells adapted to 0.4% TSP. In contrast, the increase in membrane fluidity was associated with decreased acid resistance of TSP adapted HEC-RM although the extracellular verotoxin concentration increased. Therefore, the deletion of the rpoS gene appeared to affect the changes in verotoxin concentration and acid resistance of TSP adapted E. coli O157:H7.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0168-1605
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
106
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
39-44
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Effect of trisodium phosphate adaptation on changes in membrane lipid composition, verotoxin secretion, and acid resistance of Escherichia coli O157:H7 in simulated gastric fluid.
pubmed:affiliation
Department of Food Science, Nutrition, and Health Promotion, Mississippi Agricultural and Forestry Experiment Station, Mississippi State University, Box 9805, Mississippi State, MS 39762-9805, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't