Affiliation:
1. Department of Microbiology, University of Washington, School of Medicine, Seattle, Washington, USA
2. School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, Nevada, USA
3. Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
Abstract
ABSTRACT
Members of the genus
Burkholderia
are known to be adept at biofilm formation, which presumably assists in the survival of these organisms in the environment and the host. Biofilm formation has been linked to quorum sensing (QS) in several bacterial species. In this study, we characterized
Burkholderia thailandensis
biofilm development under flow conditions and sought to determine whether QS contributes to this process.
B. thailandensis
biofilm formation exhibited an unusual pattern: the cells formed small aggregates and then proceeded to produce mature biofilms characterized by “dome” structures filled with biofilm matrix material. We showed that this process was dependent on QS.
B. thailandensis
has three acyl-homoserine lactone (AHL) QS systems (QS-1, QS-2, and QS-3). An AHL-negative strain produced biofilms consisting of cell aggregates but lacking the matrix-filled dome structures. This phenotype was rescued via exogenous addition of the three AHL signals. Of the three
B. thailandensis
QS systems, we show that QS-1 is required for proper biofilm development, since a
btaR1
mutant, which is defective in QS-1 regulation, forms biofilms without these dome structures. Furthermore, our data show that the wild-type biofilm biomass, as well as the material inside the domes, stains with a fucose-binding lectin. The
btaR1
mutant biofilms, however, are negative for fucose staining. This suggests that the QS-1 system regulates the production of a fucose-containing exopolysaccharide in wild-type biofilms. Finally, we present data showing that QS ability during biofilm development produces a biofilm that is resistant to dispersion under stress conditions.
IMPORTANCE
The saprophyte
Burkholderia thailandensis
is a close relative of the pathogenic bacterium
Burkholderia pseudomallei
, the causative agent of melioidosis, which is contracted from its environmental reservoir. Since most bacteria in the environment reside in biofilms,
B. thailandensis
is an ideal model organism for investigating questions in
Burkholderia
physiology. In this study, we characterized
B. thailandensis
biofilm development and sought to determine if quorum sensing (QS) contributes to this process. Our work shows that
B. thailandensis
produces biofilms with unusual dome structures under flow conditions. Our findings suggest that these dome structures are filled with a QS-regulated, fucose-containing exopolysaccharide that may be involved in the resilience of
B. thailandensis
biofilms against changes in the nutritional environment.
Funder
HHS | National Institutes of Health
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
35 articles.
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