Dataset Information

Identification of a novel matrix protein that promotes biofilm maturation in Vibrio fischeri.

ABSTRACT: Bacteria form communities, termed biofilms, in which cells adhere to each other within a matrix, typically comprised of polysaccharides, proteins, and extracellular DNA. Biofilm formation by the marine bacterium Vibrio fischeri requires the Syp polysaccharide, but the involvement of matrix proteins is as yet unknown. Here we identified three genes, termed bmpA, -B, and -C (biofilm maturation protein), with overlapping functions in biofilm maturation. A triple bmpABC mutant, but not single or double mutants, was defective in producing wrinkled colonies, a form of biofilm. Surprisingly, the triple mutant was competent to form pellicles, another biofilm phenotype, but they generally lacked a three-dimensional architecture. Transmission electron microscopy revealed that the extracellular matrix of the bmp mutant contained electron-dense, thread-like structures that were also present in the wild type but lacking in syp mutant strains. We hypothesized that the bmp mutant produces the Syp polysaccharide but fails to produce/export a distinct matrix component. Indeed, a mixture of the bmp and syp mutants produced a wrinkled colony. Finally, BmpA could be detected in cell-free supernatants from disrupted pellicles. Thus, this work identifies a new matrix protein necessary for biofilm maturation by V. fischeri and, based on the conservation of bmp, potentially other microbes.

SUBMITTER: Ray VA

PROVIDER: S-EPMC4285995 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Identification of a novel matrix protein that promotes biofilm maturation in Vibrio fischeri.

Ray Valerie A VA Driks Adam A Visick Karen L KL

Journal of bacteriology 20141117 3

Bacteria form communities, termed biofilms, in which cells adhere to each other within a matrix, typically comprised of polysaccharides, proteins, and extracellular DNA. Biofilm formation by the marine bacterium Vibrio fischeri requires the Syp polysaccharide, but the involvement of matrix proteins is as yet unknown. Here we identified three genes, termed bmpA, -B, and -C (biofilm maturation protein), with overlapping functions in biofilm maturation. A triple bmpABC mutant, but not single or dou ...[more]

PMID: 25404700

Similar Datasets

Project description:BackgroundMany animals and plants acquire their coevolved symbiotic partners shortly post-embryonic development. Thus, during embryogenesis, cellular features must be developed that will promote both symbiont colonization of the appropriate tissues, as well as persistence at those sites. While variation in the degree of maturation occurs in newborn tissues, little is unknown about how this variation influences the establishment and persistence of host-microbe associations.ResultsThe binary symbiosis model, the squid-vibrio (Euprymna scolopes-Vibrio fischeri) system, offers a way to study how an environmental gram-negative bacterium establishes a beneficial, persistent, extracellular colonization of an animal host. Here, we show that bacterial symbionts occupy six different colonization sites in the light-emitting organ of the host that have both distinct morphologies and responses to antibiotic treatment. Vibrio fischeri was most resilient to antibiotic disturbance when contained within the smallest and least mature colonization sites. We show that this variability in crypt development at the time of hatching allows the immature sites to act as a symbiont reservoir that has the potential to reseed the more mature sites in the host organ when they have been cleared by antibiotic treatment. This strategy may produce an ecologically significant resiliency to the association.ConclusionsThe data presented here provide evidence that the evolution of the squid-vibrio association has been selected for a nascent organ with a range of host tissue maturity at the onset of symbiosis. The resulting variation in physical and chemical environments results in a spectrum of host-symbiont interactions, notably, variation in susceptibility to environmental disturbance. This "insurance policy" provides resiliency to the symbiosis during the critical period of its early development. While differences in tissue maturity at birth have been documented in other animals, such as along the infant gut tract of mammals, the impact of this variation on host-microbiome interactions has not been studied. Because a wide variety of symbiosis characters are highly conserved over animal evolution, studies of the squid-vibrio association have the promise of providing insights into basic strategies that ensure successful bacterial passage between hosts in horizontally transmitted symbioses. Video Abstract.

Project description:Beneficial microbial symbionts are often horizontally acquired by their animal hosts from environmental sources, requiring the symbionts to complete a lifestyle transition from free-living in the environment to association with host tissues. In the model symbiosis between the Hawaiian bobtail squid and its microbial symbiont Vibrio fischeri, one mechanism used to make this transition during host colonization is the formation of biofilm-like aggregates on host mucosa. Extensive work has previously been conducted to isolate the critical factors controlling V. fischeri biofilm formation, yet much remains unknown regarding the full breadth of the biofilm-associated regulon. Here, we probed in vitro models of biofilm formation using transcriptomics, to identify novel regulatory pathways active within biofilms of the V. fischeri type strain ES114. Through comparing the gene-sets which became differentially regulated in multiple biofilm models, we discovered a shared set of 232 genes which demonstrated similar patterns in expression relative to uninduced controls. These genes contained representatives of multiple exopolysaccharide loci, genes involved in flagellar motility, and a diverse collection of other genes. Follow-up analysis suggested that these transcriptomic changes reflected true phenotypic effects, including changes in motility and cyclic-di-GMP production in biofilm-induced backgrounds. Beyond characterizing the shared biofilm response, we additionally profiled the regulatory activity of the sensor kinase RscS. This sensor kinase has previously been characterized to function as a phospho-donor within an established biofilm-inducing phospho-relay, yet our data suggests that RscS moonlights in at least one other phospho-relay that integrates downstream signaling from a homolog of the Vibrio cholerae response regulator VpsR, without a need for its established signaling partners. Overall, this study adds to our understanding of the genes involved in V. fischeri biofilm regulation, while revealing new regulatory pathways branching from previously characterized signaling networks.

Project description:Biofilms, complex communities of microorganisms surrounded by a self-produced matrix, facilitate attachment and provide protection to bacteria. A natural model used to study biofilm formation is the symbiosis between Vibrio fischeri and its host, the Hawaiian bobtail squid, Euprymna scolopes Host-relevant biofilm formation is a tightly regulated process and is observed in vitro only with strains that have been genetically manipulated to overexpress or disrupt specific regulators, primarily two-component signaling (TCS) regulators. These regulators control biofilm formation by dictating the production of the symbiosis polysaccharide (Syp-PS), the major component of the biofilm matrix. Control occurs both at and below the level of transcription of the syp genes, which are responsible for Syp-PS production. Here, we probed the roles of the two known negative regulators of biofilm formation, BinK and SypE, by generating double mutants. We also mapped and evaluated a point mutation using natural transformation and linkage analysis. We examined traditional biofilm formation phenotypes and established a new assay for evaluating the start of biofilm formation in the form of microscopic aggregates in shaking liquid cultures, in the absence of the known biofilm-inducing signal calcium. We found that wrinkled colony formation is negatively controlled not only by BinK and SypE but also by SypF. SypF is both required for and inhibitory to biofilm formation. Together, these data reveal that these three regulators are sufficient to prevent wild-type V. fischeri from forming biofilms under these conditions.IMPORTANCE Bacterial biofilms promote attachment to a variety of surfaces and protect the constituent bacteria from environmental stresses, including antimicrobials. Understanding the mechanisms by which biofilms form will promote our ability to resolve them when they occur in the context of an infection. In this study, we found that Vibrio fischeri tightly controls biofilm formation using three negative regulators; the presence of a single one of these regulators was sufficient to prevent full biofilm development, while disruption of all three permitted robust biofilm formation. This work increases our understanding of the functions of specific regulators and demonstrates the substantial negative control that one benign microbe exerts over biofilm formation, potentially to ensure that it occurs only under the appropriate conditions.

Project description:The mutualistic symbiont Vibrio fischeri builds a symbiotic biofilm during colonization of squid hosts. Regulation of the exopolysaccharide component, termed Syp, has been examined in strain ES114, where production is controlled by a phosphorelay that includes the inner membrane hybrid histidine kinase RscS. Most strains that lack RscS or encode divergent RscS proteins cannot colonize a squid host unless RscS from a squid symbiont is heterologously expressed. In this study, we examine V. fischeri isolates worldwide to understand the landscape of biofilm regulation during beneficial colonization. We provide a detailed study of three distinct evolutionary groups of V. fischeri and find that while the RscS-Syp biofilm pathway is required in one of the groups, two other groups of squid symbionts require Syp independent of RscS. Mediterranean squid symbionts, including V. fischeri SR5, colonize without an RscS homolog encoded by their genome. Additionally, group A V. fischeri strains, which form a tightly related clade of Hawaii isolates, have a frameshift in rscS and do not require the gene for squid colonization or competitive fitness. These same strains have a frameshift in sypE, and we provide evidence that this group A sypE allele leads to an upregulation in biofilm activity. Thus, this work describes the central importance of Syp biofilm in colonization of diverse isolates and demonstrates that significant evolutionary transitions correspond to regulatory changes in the syp pathway.IMPORTANCE Biofilms are surface-associated, matrix-encased bacterial aggregates that exhibit enhanced protection to antimicrobial agents. Previous work has established the importance of biofilm formation by a strain of luminous Vibrio fischeri bacteria as the bacteria colonize their host, the Hawaiian bobtail squid. In this study, expansion of this work to many natural isolates revealed that biofilm genes are universally required, yet there has been a shuffling of the regulators of those genes. This work provides evidence that even when bacterial behaviors are conserved, dynamic regulation of those behaviors can underlie evolution of the host colonization phenotype. Furthermore, this work emphasizes the importance of investigating natural diversity as we seek to understand molecular mechanisms in bacteria.

Dataset Information

Identification of a novel matrix protein that promotes biofilm maturation in Vibrio fischeri.

Publications

Identification of a novel matrix protein that promotes biofilm maturation in Vibrio fischeri.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets