Table 2.

Bacterial factors involved in biofilm formation and pathogenesis.

Bacteria	Factors	Function		Refs
		Biofilm Formation	Pathogenicity
Listeria monocytogenes	ActA (actin polymerization protein)	Bacterial sedimentation and aggregation	Rearrange host cytoskeletal structure and promote the cell-to-cell spread	[75]
	LAP (listeria adhesion protein)	Expression in recombinant Lactobacillus enhanced biofilm formation	Epithelial adhesion and translocation through the epithelial barrier	[50,51]
	PrfA (protein regulatory factor)	Regulate the expression of ActA that is necessary for biofilm formation	Regulatory protein that regulates the synthesis of multiple virulence factors	[71]
	WTA (wall teichoic acid)	Maintain cell wall (peptidoglycan) architecture and participate in biofilm formation	Induce inflammatory response	[77]
Staphylococcus aureus	Bap (biofilm-associated protein)	Adhesion to inert surfaces and intercellular adhesion in the development of biofilm formation	Establish persistent infection on a mouse infection model	[101,103]
	Protein A	Cell-to-cell adhesion in biofilm development; a major proteinaceous component in S. aureus biofilms	Help S. aureus to evade immune system in vivo	[99,100]
	PIA (polysaccharide intercellular adhesin)	Cell-to-cell binding in biofilm formation	Establish persistent in vivo infection	[91,93]
	Teichoic acid	Maintain cell wall (peptidoglycan) architecture and participate in biofilm formation	Induce inflammatory response	[76,77,111]
	FnBP (fibronectin-binding proteins)	Cell-to-cell adhesion through low-affinity homophilic interaction between neighboring cells	Promote bacterial attachment to host fibronectin for adhesion and colonization	[105,107]
	SasG (S. aureus surface protein G)	Zinc activated SasG-mediated biofilm formation	Adhesion to epithelial cells	[89,109]
Salmonella enterica	Fimbria (SEF17)	Cell-to-cell interaction in biofilm formation	Bind to human fibronectin and facilitate cell invasion	[144,145]
	Bap (biofilm-associated protein)	Bap and curli can help form strong biofilms in both biotic and abiotic surface	Colonization, intestinal persistence, invasion to liver and spleen and lethality in mice	[126]
	CsgD, BcsA	Curli and cellulose synthesis	Colonization, biofilm formation and vertical transmission to egg	[146]
Escherichia coli	Curli made with CsgA and CsgB	Adherence to abiotic surfaces	Adhere to epithelial cells when over expressed	[129,135]
	Fim (fimbriae)	Biofilm formation on polystyrol	Adhesion to epithelial cell lines	[136]
Enteroaggregative E. coli (EAEC)	Aggregative adherence fimbriae (AAF)	Mediate biofilm formation on abiotic surfaces	Bind to MUC1 on epithelial cells	[142,143]
Pseudomonas aeruginosa	PqsR	A key component of Pseudomonas quinolone signal system	Regulate the production of virulence factors, pyocyanin and hydrogen cyanide	[147]
	Flagellum	Swimming motility and biofilm formation	Flagella is an important virulence factor. The flagellum-deficient strain showed less invasion in the mouse burn wound model and less colonization in the murine intestine	[148,149]
	Type IV pili	Twitching motility, and adhesion to abiotic surfaces	Adhesion to eukaryotic cells and pathogenesis	[150]