Biomolecular Mechanisms of Pseudomonas aeruginosa and Escherichia coli Biofilm Formation

Abstract

Pseudomonas aeruginosa and Escherichia coli are the most prevalent Gram-negative biofilm forming medical device associated pathogens, particularly with respect to catheter associated urinary tract infections. In a similar manner to Gram-positive bacteria, Gram-negative biofilm formation is fundamentally determined by a series of steps outlined more fully in this review, namely adhesion, cellular aggregation, and the production of an extracellular polymeric matrix. More specifically this review will explore the biosynthesis and role of pili and flagella in Gram-negative adhesion and accumulation on surfaces in Pseudomonas aeruginosa and Escherichia coli. The process of biofilm maturation is compared and contrasted in both species, namely the production of the exopolysaccharides via the polysaccharide synthesis locus (Psl), pellicle Formation (Pel) and alginic acid synthesis in Pseudomonas aeruginosa, and UDP-4-amino-4-deoxy-l-arabinose and colonic acid synthesis in Escherichia coli. An emphasis is placed on the importance of the LuxR homologue sdiA; the luxS/autoinducer-II; an autoinducer-III/epinephrine/norepinephrine and indole mediated Quorum sensing systems in enabling Gram-negative bacteria to adapt to their environments. The majority of Gram-negative biofilms consist of polysaccharides of a simple sugar structure (either homo- or heteropolysaccharides) that provide an optimum environment for the survival and maturation of bacteria, allowing them to display increased resistance to antibiotics and predation.

Cells of Escherichia coli are protected against severe chemical stress by co-habiting cell aggregates formed by Pseudomonas aeruginosa

“…Thus, it is possible that this structural support might have been reinforced by DNA from lysed cells of strain MG1655[pSB536] thereby increasing the protective effect of the biofilm matrix. Additionally, extracellular polymers of strain MG1655[pSB536], such as curli fibers or cellulose (Laverty et al 2014;Serra and Hengge 2014), might have also interacted with those of strain PAO1. Earlier studies have shown that P. aeruginosa can facilitate biofilm formation of E. coli in a flow-cell capillary (Klayman et al 2009) and on silicone coupons in synthetic urine medium (Cerqueira et al 2013) indicating potential specific interactions between these two bacterial species during biofilm formation.…”

A Novel RNase 3/ECP Peptide for Pseudomonas aeruginosa Biofilm Eradication That Combines Antimicrobial, Lipopolysaccharide Binding, and Cell-Agglutinating Activities

“…Biofilm formation is induced by genotypic and phenotypic changes of the planktonic microorganisms which lead to an ensuing multilayered cell cluster structure coated by an external polysaccharide matrix composed of polysaccharides, proteins, and extracellular DNA (8). P. aeruginosa, once organized in a biofilm structure, becomes more resistant to antibiotic agents and immune system clearance and thus requires a more elaborate strategy for successful treatment of associated infections (9).…”

The Social Life of African Trypanosomes

“…Examples of social interactions include swarming motility, biofilm formation and quorum sensing; these are well studied in bacteria [1][2][3][4][5] and in the free-living amoeba Dictyostelium discoideum [6], but are not widely recognised in parasites.…”