Sub-lethal Ethanol Treatment Affects the Fatty Acids Composition and the Survival of Cronobacter sakazakii Exposure to Subsequent Lethal Stresses
Date Issued
2011
Date
2011
Author(s)
Huang, Yi-Ting
Abstract
In the present study, Cronobacter sakazakii was exposed to a sub-lethal dose of 5% ethanol for 60 min at room temperatue (ethanol shock). The effect of ethanol shock on the survival of C. sakazakii subjected to subsequent adverse conditions including high ethanol concentration (15%), high temperature (51℃), low temperature (4 and -20 ℃), acid (pH 3.3), high osmotic pressure (Tryptic soy broth + 75% sorbitol, Aw= 0.83) , air drying as well as in the presence of various organic acid (125 mM lactic acid, acetic acid, propionic acid, citric acid and tartaric acid) was investigated. Besides fatty acid profile of the cells of ethanol-shocked C. sakazakii were compared with those of the non-shocked cells. Results revealed that ethanol shock cells significantly (P<0.05) enhanced the resistance of C. sakazakii to all the lethal stresses examined. Although survival of ethanol-shocked and non-shocked cells showed no significantly difference (P>0.05) after freeze-drying, survival of the ethanol-chocked C. sakazakii was significantly higher (P<0.05) than that of non-shocked cells after spray-drying. Furthermore, ethanol shock caused a change in the proportions of the saturated and unsaturated fatty acids. The ratio of saturated to unsaturated fatty acid and the proportion of cyclopropaneoctanoic acid in the ethanol-shocked cells was significantly higher (P<0.05) than that observed in the non-shocked cells.
Subjects
sub-lethal ethanol
fatty acids composition
Type
thesis
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