The green tea polyphenol EGCG inhibits E. coli biofilm formation by impairing amyloid curli fibre assembly and downregulating the biofilm regulator CsgD via the σ(E) -dependent sRNA RybB

Mol Microbiol. 2016 Jul;101(1):136-51. doi: 10.1111/mmi.13379. Epub 2016 May 6.


In bacterial biofilms, which are often involved in chronic infections, cells are surrounded by a self-produced extracellular matrix that contains amyloid fibres, exopolysaccharides and other biopolymers. The matrix contributes to the pronounced resistance of biofilms against antibiotics and host immune systems. Being highly inflammatory, matrix amyloids such as curli fibres of Escherichia coli can also play a role in pathogenicity. Using macrocolony biofilms of commensal and pathogenic E. coli as a model system, we demonstrate here that the green tea polyphenol epigallocatachin gallate (EGCG) is a potent antibiofilm agent. EGCG virtually eliminates the biofilm matrix by directly interfering with the assembly of curli subunits into amyloid fibres, and by triggering the σ(E) cell envelope stress response and thereby reducing the expression of CsgD - a crucial activator of curli and cellulose biosynthesis - due to csgD mRNA targeting by the σ(E) -dependent sRNA RybB. These findings highlight EGCG as a potential adjuvant for antibiotic therapy of biofilm-associated infections. Moreover, EGCG may support therapies against pathogenic E. coli that produce inflammatory curli fibres along with Shigatoxin.

MeSH terms

  • Amyloid / genetics
  • Amyloid / metabolism*
  • Anti-Infective Agents
  • Bacterial Adhesion / physiology
  • Bacterial Proteins / antagonists & inhibitors
  • Biofilms / drug effects*
  • Catechin / analogs & derivatives*
  • Catechin / metabolism
  • Catechin / pharmacology
  • Down-Regulation / drug effects
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli / physiology*
  • Escherichia coli Proteins / antagonists & inhibitors
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Promoter Regions, Genetic
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Untranslated / genetics
  • RNA, Small Untranslated / metabolism
  • Sigma Factor / metabolism*
  • Tea / chemistry
  • Trans-Activators / antagonists & inhibitors
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*


  • Amyloid
  • Anti-Infective Agents
  • Bacterial Proteins
  • CsgD protein, E coli
  • Escherichia coli Proteins
  • RNA, Messenger
  • RNA, Small Untranslated
  • Sigma Factor
  • Tea
  • Trans-Activators
  • sporulation-specific sigma factors
  • Crl protein, Bacteria
  • Catechin
  • epigallocatechin gallate