Table 2.

A summary of the mechanisms of actions of tannins (at sub-MIC level) against some of the bacteria responsible for poultry infections

Phytochemical	Bacteria	Target site	Mode of action	References
Tannins	E. coli	Biofilm formation and motility genes	Repression in the production of curli genes (csgB and csgD) and downregulation in the expression of motility genes (fimA, fimH, flhD, motB, qseB, qseC)	Yang et al. (2016)
Tannins	E. coli	Motility genes and quorum sensing	Downregulation in the expression of motility genes (fliA, fliY, fljB, flhC, fimD) and repression in the expression of quorum sensing genes (sdiA and srgE)	Li et al. (2014)
Tannins/phenolic compounds	Salmonella	Type III secretion system/pathogenicity genes	Downregulation in the expression of the type III secretion system-related genes (hilA, hilC, invA, invF, sirA and sirB)	Salaheen et al. (2016)
Condensed tannins (proanthocyanidins)	Salmonella	Pathogenicity island 1/virulence secretion system	Suppression in the secretion of the pathogenicity island SPI1	Morita et al. (2016)