Regulation of biofilm formation in Pseudomonas and Burkholderia species

Abstract

SummaryIn the present review, we describe and compare the molecular mechanisms that are involved in the regulation of biofilm formation by Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas aeruginosa and Burkholderia cenocepacia. Our current knowledge suggests that biofilm formation is regulated by cyclic diguanosine-5′-monophosphate (c-di-GMP), small RNAs (sRNA) and quorum sensing (QS) in all these bacterial species. The systems that employ c-di-GMP as a second messenger regulate the production of exopolysaccharides and surface proteins which function as extracellular matrix components in the biofilms formed by the bacteria. The systems that make use of sRNAs appear to regulate the production of exopolysaccharide biofilm matrix material in all these species. In the pseudomonads, QS regulates the production of extracellular DNA, lectins and biosurfactants which all play a role in biofilm formation. In B. cenocepacia QS regulates the expression of a large surface protein, lectins and extracellular DNA that all function as biofilm matrix components. Although the three regulatory systems all regulate the production of factors used for biofilm formation, the molecular mechanisms involved in transducing the signals into expression of the biofilm matrix components differ between the species. Under the conditions tested, exopolysaccharides appears to be the most important biofilm matrix components for P. aeruginosa, whereas large surface proteins appear to be the most important biofilm matrix components for P. putida, P. fluorescens, and B. cenocepacia.

The Cyclic AMP-Vfr Signaling Pathway in Pseudomonas aeruginosa Is Inhibited by Cyclic Di-GMP

“…The RSCV phenotype is most commonly caused by mutations that result in changed metabolism of the secondary messenger molecule cyclic di-GMP (c-di-GMP) (7,(16)(17)(18). c-di-GMP has been shown to positively regulate biofilm formation in various bacteria, including P. aeruginosa, at the transcriptional, translational, and posttranslational levels (19,20). The synthesis of c-di-GMP in bacteria is accomplished by diguanylate cyclases (DGCs), whereas degradation of c-di-GMP is catalyzed by specific phosphodiesterases (PDEs) (19)(20)(21).…”

“…c-di-GMP has been shown to positively regulate biofilm formation in various bacteria, including P. aeruginosa, at the transcriptional, translational, and posttranslational levels (19,20). The synthesis of c-di-GMP in bacteria is accomplished by diguanylate cyclases (DGCs), whereas degradation of c-di-GMP is catalyzed by specific phosphodiesterases (PDEs) (19)(20)(21). The DGCs and PDEs frequently harbor sensory domains that enable translation of diverse environmental cues into specific c-di-GMP levels.…”

Aquaporins in Infection and Inflammation

“…The bacteria will stay in a non-virulent, slow-growing state. When the population density has reached a certain threshold (quorum) the concentrations of QS molecules can change the transcriptional behaviour of the bacteria and the size of the bacteria population as a whole [136][137][138]. The QS thus enables the bacteria population to live as a community, almost as a multicellular organism.…”

Laboratory Evolution of Microbial Interactions in Bacterial Biofilms

“…Despite the increasing knowledge of the ecology (13,15,16), genetics (17)(18)(19), or physical mechanisms (20,21) of biofilm development and the mechanisms that stabilize cooperation during biofilm formation (7,9,10,22), we still know little about the long-term evolutionary dynamics within biofilm communities. It is unclear how social interactions shape biofilm evolution and how evolution in structured environments shift the balance between competition and mutualism.…”