Related Experiment Video
Updated: Dec 14, 2025
Improved Enzyme Protection Assay to Study Staphylococcus aureus Internalization and Intracellular Efficacy of Antimicrobial Compounds
Published on: September 8, 2021
Effect of epigallocatechin gallate on gene expression of Staphylococcus aureus
Apisada Kitichalermkiat1, Mao Katsuki1, Jun Sato2
1Division of Food Science and Biotechnology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan.
Objectives:
Staphylococcus aureus is an important nosocomial pathogen that produces various extracellular toxins. Epigallocatechin gallate (EGCg) is a polyphenol that is abundant in green tea. EGCg displays strong antibacterial activity against Gram-positive bacteria. The effect of EGCg on gene expression by S. aureus was investigated to clarify the mechanism underlying its antibacterial action.
Methods:
Microarray analysis was performed on S. aureus treated with or without 500mg/L EGCg. Differentially expressed genes were identified and their changes at the transcription level were confirmed using real-time quantitative polymerase chain reaction (qPCR). The membrane potential of cells treated with or without EGCg were observed under fluorescence microscopy.
Results:
Microarray analysis revealed that EGCg treatment of S. aureus resulted in increased and decreased transcription of 75 and 72 genes, respectively. Increased transcription exceeding 1-log2-fold change of genes related to membrane transport included gntP, gntK, rumA, SAOUHSC_02723, SAOUHSC_01311, and vraS. Decreased transcription was observed in genes involved in toxin production and stress response (hlgA, SAOUHSC_01110, hly, hlgB, efb, and hlgC). All changes in transcription were confirmed using real-time qPCR. The membrane potential of S. aureus treated with 500mg/L EGCg markedly decreased, indicating that EGCg damaged the cell membrane.
Conclusions:
S. aureus increases the transcription of genes involved in membrane transport to recover membrane function. EGCg can potentially serve as a natural antibacterial agent to control the growth and toxin production of S. aureus.
