Antagonism by salt addition on treatment with short chain fatty acids with one carboxylic acid against Escherichia coli 0157:H7

초록

In our previous study, combinations of organic acid and salt showed varying effects against E. coli 0157:H7 depending on the type of acid. Therefore, in order to determine whether chain length and acid structure could alter the combined effect with salt against E. con 0157:H7, the effectiveness of combining each of six types of short chain fatty acids (formic, acetic, oxalic, propionic, butyric, or 3-hydroxybutyric acid) with salt against E. coli 0157:H7 was tested in this study. In addition, to elucidate the antagonistic mechanism of some acids by the addition of salt, changes in the fatty acid composition of E. coli 0157:H7 cell membrane were determined. Treatment with a combination of oxalic acid and salts led to a greater reduction in E. coli 0157:H7 compared to the acid treatment alone. However, resistance to short chain fatty acids was observed when formic, acetic, propionic, butyric, and 3-hydroxybutyric acid were combined with salt. An enhanced antagonistic effect was observed for simple short chain fatty acids with only one carboxyl acid in their chemical structure. Treatment with salt significantly increased the percentage of SFAS and CFAs in E. coli 0157:H7. However, total fatty acid content of E. coli 0157:H7 treated with a combination of acid and salt did not differ significantly from that of E. coil 0157:H7 treated with acid alone; therefore, the protective mechanism of combining some short chain fatty acids and salt against E. coli 0157:H7 requires further study. (C) 2016 Published by Elsevier Ltd.

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