Table 3.
Important characteristics of P. aeruginosa BF.
| Functions | Components | Sub Components |
Molecules | Function |
|---|---|---|---|---|
| Matrix Adhesive material Protective barrier |
ECMs | EPS | PsL * | Initiation and maintenance of BF Supplies cell surface attachment Supplies intercellular interactions |
| PeL *, ** | Essential for forming pellicles at the air–liquid interface and solid surface-associated BFs [98,102] Platform for BF structure Supplies protection against aminoglycosides [100,103] Binding with eDNA of the BF [104,105]. Compensates for a lack of PsL in the BF periphery [104] |
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| Alginate *** | Factor used to distinguish mucoid or non-mucoid P. aeruginosa BFs Retains water and nutrients Supplies antibiotic resistance and immune evasion [105,106,107] |
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| eDNA | Formation of cation gradients Antibiotic resistance Nutrient source Early BF development [99,108,109,110] Major proinflammatory factor for P. aeruginosa BFs [111] |
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| Proteins | Flagella | Act as an adhesin to help initial bacterial attachment to the surface [112] |
||
| Type IV pili | Contribute to the formation of mushroom-like BF cap structures [113,114] | |||
| CdrA adhesin | Interacts with PsL and increases BF stability [115]. | |||
| Cup fimbriae | Important roles in cell-to-cell interaction during the first stage of BF formation [115] | |||
| Intercellular communication system enabling bacteria to sense their own population density. | QS system | NAHSL AI-2 |
las | Regulate several hundred genes in P. aeruginosa [116,117] Regulate the bacterial phenotype, spatial differentiation in BFs, motility, and BF formation [118] |
| Rhl | ||||
| PQS | ||||
| Integrated QS (IQS) | ||||
* Psl and Pel production occurs through the c-di-GMP signaling pathway owing to environmental signals; ** the Pel production mechanism is implicated in the association of LPS. The complete biochemical composition of Pel has not yet been discovered. Currently, Pel is known to be made of cationic amino sugars; *** mainly produced by strains of P. aeruginosa isolated from patients affected by cystic fibrosis (CF); NAHSL = N-acyl-homoserine lactones; AI-2 = autoinducer 2.