Formation mechanism of injured bacteria after disinfection with epigallocatechin gallate (EGCG) as a disinfectant

This study explored the effects of epigallocatechin gallate (EGCG), the main antibacterial component of tea polyphenols, on Escherichia coli in terms of disinfection damage and the underlying mechanisms. The researchers assessed inactivation and injury rates, cell morphology, and antioxidant indicators of E. coli when subjected to different concentrations of EGCG. The results showed that varying EGCG concentrations produced damaged bacteria, with the extent of damage depending on EGCG dosage and treatment duration. The disinfection process involving EGCG resulted in oxidative damage in E. coli, evoking alterations in the antioxidant system of the affected bacteria. During disinfection-induced bacterial injury, E. coli showed the active regulation of metabolism and redox activities in response to EGCG-induced environmental stimuli. Transcriptomic analysis was conducted to investigate the damage mechanism at the gene level. The damaged E. coli countered oxidative stress by adjusting gene expression related to peroxidase and glutathione metabolism processes. In this way, E. coli adjusts its gene expression to alleviate the detrimental effects of EGCG-induced oxidative stress and maintain cellular homeostasis. These findings contribute to our understanding of tea polyphenols' disinfection effects and provide insights into EGCG's mechanisms of damaging bacteria such as E. coli.

• The dosage of EGCG affects the inactivation of E. coli and the formation of injured bacteria.

• High EGCG levels cause oxidative damage to the cell membranes of injured bacteria.

• Injured bacteria regulate redox and other activities to respond to EGCG stimuli.

• EGCG downregulates genes in injured bacteria to block outer membrane synthesis.