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AFM study of the differential inhibitory effects of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) against Gram-positive and Gram-negative bacteria

Title
AFM study of the differential inhibitory effects of the green tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) against Gram-positive and Gram-negative bacteria
Authors
Cui Y.Oh Y.J.Lim J.Youn M.Lee I.Pak H.K.Park W.Jo W.Park S.
Ewha Authors
조윌렴박성수
SCOPUS Author ID
조윌렴scopus
Issue Date
2012
Journal Title
Food Microbiology
ISSN
0740-0020JCR Link
Citation
vol. 29, no. 1, pp. 80 - 87
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
(-)-Epigallocatechin-3-gallate (EGCG), a main constituent of tea catechins, affects Gram-positive and Gram-negative bacteria differently; however, the underlying mechanisms are not clearly understood. Atomic force microscopy (AFM) was used to compare morphological alterations in Gram-positive and Gram-negative bacteria induced by EGCG and by H 2O 2 at sub-minimum inhibitory concentrations (MICs). EGCG initially induced aggregates in the cell envelopes of Staphylococcus aureus and eventually caused cell lysis, which was not observed in cells treated with H 2O 2. It initially induced nanoscale perforations or microscale grooves in the cell envelopes of Escherichia coli O157:H7 which eventually disappeared, similar to E. coli cells treated with H 2O 2. An E. coli O157:H7 tpx mutant, with a defect in thioredoxin-dependent thiol peroxidase (Tpx), was more severely damaged by EGCG when compared with its wild type. Similar differing effects were observed in other Gram-positive and Gram-negative bacteria when exposed to EGCG; it caused aggregated in Streptococcus mutans, while it caused grooves in Pseudomonas aeruginosa. AFM results suggest that the major morphological changes of Gram-negative bacterial cell walls induced by EGCG depend on H 2O 2 release. This is not the case for Gram-positive bacteria. Oxidative stress in Gram-negative bacteria induced by EGCG was confirmed by flow cytometry. © 2011 Elsevier Ltd.
DOI
10.1016/j.fm.2011.08.019
Appears in Collections:
자연과학대학 > 물리학전공 > Journal papers
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