کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6394115 | 1330460 | 2012 | 8 صفحه PDF | دانلود رایگان |
The mechanism of the combined anti-bacterial effect of green tea extract (GTE) and NaCl against Staphylococcus aureus NBRC 13276 and Escherichia coli O157:H7 was investigated. After treatment for 1 h, GTE was more effective against S. aureus than E. coli O157:H7, and combined GTE/NaCl treatment caused greater cellular damage in S. aureus NBRC 13276, where it was bactericidal, than E. coli O157:H7. Compared to treatment with 1.0 mg/mL GTE, which had no effect on the survival rate of E. coli O157:H7 after 48 h, treatment with 4% NaCl alone caused greater cellular damage. Moreover, bacteria pretreated with NaCl showed delayed growth in the presence of GTE. It is therefore likely that susceptibility of E. coli O157:H7 to GTE was increased by exposure to NaCl. E. coli O157:H7 pretreated with GTE and NaCl did not multiply in the presence of GTE. Visualization of the catechin components of GTE-treated bacteria using an electron microscope and SDS-PAGE analysis of cell proteins showed that GTE attached to proteins on the surface of the bacteria to form high-molecular weight complexes, suggesting the possibility that GTE inhibits the uptake and secretion of substrates and inhibits enzyme activity. Notably, after the GTE treatment for 1 h, both bacterial strains suffered injury but recovered by cultivation in rich medium. The damage and aggregation of proteins caused by GTE treatment were repaired upon treatment with LP diluent.
⺠Green Tea Extract (GTE) was more effective against S. aureus than E. coli O157:H7. ⺠Combined GTE/NaCl treatment caused greater cellular damage in S. aureus NBRC 13276. ⺠GTE attached to proteins on the surface of the bacteria to form high-molecular weight complexes. ⺠Susceptibility of E. coli O157:H7 to GTE was increased by exposure to NaCl.
Journal: Food Control - Volume 25, Issue 1, May 2012, Pages 225-232