scholarly journals Arabinose Induces Pellicle Formation by Vibrio fischeri

2013 ◽  
Vol 79 (6) ◽  
pp. 2069-2080 ◽  
Author(s):  
Karen L. Visick ◽  
Kevin P. Quirke ◽  
Sheila M. McEwen
Keyword(s):  
Biofilm Formation ◽  
Sole Carbon Source ◽  
Marine Bacterium ◽  
Vibrio Fischeri ◽  
Luria Bertani ◽  
Phenol Red ◽  
Liquid Interfaces ◽  
Acid Base ◽  
Pellicle Formation ◽  
Content Type

ABSTRACTBiofilms are multicellular communities of bacteria attached to a surface and embedded in a protective matrix. In many cases, the signals that induce biofilm formation are unknown. Here, we report that biofilm formation by the marine bacteriumVibrio fischerican be induced by the addition of arabinose to LBS (Luria-Bertani-salt), a tryptone-based medium. Growth of cells in the presence of 0.2% arabinose, but not other sugars, induced the production of a pellicle at the air/liquid interfaces of static cultures.V. fischerifailed to grow on arabinose as the sole carbon source, suggesting that pellicle production did not occur as a result of increased growth, but experiments using the acid/base indicator phenol red suggested thatV. fischerimay partially metabolize arabinose. Pellicle production was independent of thesyppolysaccharide locus but was altered upon disruption of thebcscellulose locus. Through a screen for mutants defective for pellicle production, we found that loss of motility disrupted the formation of the arabinose-induced pellicle. Among the ∼20 mutants that retained motility were strains with insertions in a putativemshpilus locus and a strain with a defect inyidK, which is involved in galactose catabolism. Mutants with themshgene disrupted grew poorly in the presence of arabinose, while theyidKmutant appeared to be “blind” to the presence of arabinose. Finally, arabinose impaired symbiotic colonization byV. fischeri. This work thus identifies a novel signal and new pathways involved in control of biofilm formation byV. fischeri.

scholarly journals Identification of a Transcriptomic Network Underlying the Wrinkly and Smooth Phenotypes of Vibrio fischeri

2020 ◽  
Vol 203 (3) ◽  
Author(s):  
Alba Chavez-Dozal ◽  
William Soto ◽  
Michele K. Nishiguchi
Keyword(s):  
Biofilm Formation ◽  
Marine Bacterium ◽  
Vibrio Fischeri ◽  
Life History Strategy ◽  
Complex Form ◽  
Bacterial Colony ◽  
Content Type ◽  
Naturally Occurring ◽  
Light Organs ◽  
Genetic Mechanisms

ABSTRACT Vibrio fischeri is a cosmopolitan marine bacterium that oftentimes displays different colony morphologies, switching from a smooth to a wrinkly phenotype in order to adapt to changes in the environment. This wrinkly phenotype has also been associated with increased biofilm formation, an essential characteristic for V. fischeri to adhere to substrates, to suspended debris, and within the light organs of sepiolid squids. Elevated levels of biofilm formation are correlated with increased microbial survival of exposure to environmental stressors and the ability to expand niche breadth. Since V. fischeri has a biphasic life history strategy between its free-living and symbiotic states, we were interested in whether the wrinkly morphotype demonstrated differences in its expression profile in comparison to the naturally occurring and more common smooth variant. We show that genes involved in major biochemical cascades, including those involved in protein sorting, oxidative stress, and membrane transport, play a role in the wrinkly phenotype. Interestingly, only a few unique genes are specifically involved in macromolecule biosynthesis in the wrinkly phenotype, which underlies the importance of other pathways utilized for adaptation under the conditions in which Vibrio bacteria are producing this change in phenotype. These results provide the first comprehensive analysis of the complex form of genetic activation that underlies the diversity in morphologies of V. fischeri when switching between two different colony morphotypes, each representing a unique biofilm ecotype. IMPORTANCE The wrinkly bacterial colony phenotype has been associated with increased squid host colonization in V. fischeri. The significance of our research is in identifying the genetic mechanisms that are responsible for heightened biofilm formation in V. fischeri. This report also advances our understanding of gene regulation in V. fischeri and brings to the forefront a number of previously overlooked genetic networks. Several loci that were identified in this study were not previously known to be associated with biofilm formation in V. fischeri.

scholarly journals A Light-Regulated Type I Pilus Contributes toAcinetobacter baumanniiBiofilm, Motility, and Virulence Functions

2018 ◽  
Vol 86 (9) ◽  
Author(s):  
Cecily R. Wood ◽  
Emily J. Ohneck ◽  
Richard E. Edelmann ◽  
Luis A. Actis
Keyword(s):  
Biofilm Formation ◽  
Galleria Mellonella ◽  
Alveolar Epithelial Cells ◽  
Ecological Niches ◽  
Type I ◽  
Pellicle Formation ◽  
Content Type ◽  
Alveolar Epithelial ◽  
Abiotic Surfaces ◽  
Cells Cultured

ABSTRACTTranscriptional analyses ofAcinetobacter baumanniiATCC 17978 showed that the expression of A1S_2091 was enhanced in cells cultured in darkness at 24°C through a process that depended on the BlsA photoreceptor. Disruption of A1S_2091, a component of the A1S_2088-A1S_2091 polycistronic operon predicted to code for a type I chaperone/usher pilus assembly system, abolished surface motility and pellicle formation but significantly enhanced biofilm formation on plastic by bacteria cultured in darkness. Based on these observations, the A1S_2088-A1S_2091 operon was named thephotoregulatedpilus ABCD (prpABCD) operon, with A1S_2091 coding for the PrpA pilin subunit. Unexpectedly, comparative analyses of ATCC 17978 andprpAisogenic mutant cells cultured at 37°C showed the expression of light-regulated biofilm biogenesis and motility functions under a temperature condition that drastically affects BlsA production and its light-sensing activity. These assays also suggest that ATCC 17978 cells produce alternative light-regulated adhesins and/or pilus systems that enhance bacterial adhesion and biofilm formation at both 24°C and 37°C on plastic as well as on the surface of polarized A549 alveolar epithelial cells, where the formation of bacterial filaments and cell chains was significantly enhanced. The inactivation ofprpAalso resulted in a significant reduction in virulence when tested by using theGalleria mellonellavirulence model. All these observations provide strong evidence showing the capacity ofA. baumanniito sense light and interact with biotic and abiotic surfaces using undetermined alternative sensing and regulatory systems as well as alternative adherence and motility cellular functions that allow this pathogen to persist in different ecological niches.

scholarly journals Pumilacidin-Like Lipopeptides Derived from Marine Bacterium Bacillus sp. Strain 176 Suppress the Motility of Vibrio alginolyticus

2017 ◽  
Vol 83 (12) ◽  
Author(s):  
Pengyuan Xiu ◽  
Rui Liu ◽  
Dechao Zhang ◽  
Chaomin Sun
Keyword(s):  
Cell Death ◽  
Antibiotic Resistance ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Marine Bacterium ◽  
Vibrio Alginolyticus ◽  
Bacterial Motility ◽  
Great Promise ◽  
Content Type ◽  
Cyclic Lipopeptides

ABSTRACT Bacterial motility is a crucial factor during the invasion and colonization processes of pathogens, which makes it an attractive therapeutic drug target. Here, we isolated a marine bacterium (Vibrio alginolyticus strain 178) from a seamount in the tropical West Pacific that exhibits vigorous motility on agar plates and severe pathogenicity to zebrafish. We found that V. alginolyticus 178 motility was significantly suppressed by another marine bacterium, Bacillus sp. strain 176, isolated from the same niche. We isolated, purified, and characterized two different cyclic lipopeptides (CLPs) from Bacillus sp. 176 using high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The two related CLPs have a pumilacidin-like structure and were both effective inhibitors of V. alginolyticus 178 motility. The CLPs differ by only one methylene group in their fatty acid chains. In addition to motility suppression, the CLPs also induced cell aggregation in the medium and reduced adherence of V. alginolyticus 178 to glass substrates. Notably, upon CLP treatment, the expression levels of two V. alginolyticus flagellar assembly genes (flgA and flgP) dropped dramatically. Moreover, the CLPs inhibited biofilm formation in several other strains of pathogenic bacteria without inducing cell death. This study indicates that CLPs from Bacillus sp. 176 show promise as antimicrobial lead compounds targeting bacterial motility and biofilm formation with a low potential for eliciting antibiotic resistance. IMPORTANCE Pathogenic bacteria often require motility to establish infections and subsequently spread within host organisms. Thus, motility is an attractive therapeutic target for the development of novel antibiotics. We found that cyclic lipopeptides (CLPs) produced by marine bacterium Bacillus sp. strain 176 dramatically suppress the motility of the pathogenic bacterium Vibrio alginolyticus strain 178, reduce biofilm formation, and promote cellular aggregation without inducing cell death. These findings suggest that CLPs hold great promise as potential drug candidates targeting bacterial motility and biofilm formation with a low overall potential for triggering antibiotic resistance.

scholarly journals Tools for Rapid Genetic Engineering of Vibrio fischeri

2018 ◽  
Vol 84 (14) ◽  
Author(s):  
Karen L. Visick ◽  
Kelsey M. Hodge-Hanson ◽  
Alice H. Tischler ◽  
Allison K. Bennett ◽  
Vincent Mastrodomenico
Keyword(s):  
Antibiotic Resistance ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Single Step ◽  
Universal Primers ◽  
Resistance Marker ◽  
Content Type ◽  
Flp Recombinase ◽  
Overlap Extension

ABSTRACT Vibrio fischeri is used as a model for a number of processes, including symbiosis, quorum sensing, bioluminescence, and biofilm formation. Many of these studies depend on generating deletion mutants and complementing them. Engineering such strains, however, is a time-consuming, multistep process that relies on cloning and subcloning. Here, we describe a set of tools that can be used to rapidly engineer deletions and insertions in the V. fischeri chromosome without cloning. We developed a uniform approach for generating deletions using PCR splicing by overlap extension (SOEing) with antibiotic cassettes flanked by standardized linker sequences. PCR SOEing of the cassettes to sequences up- and downstream of the target gene generates a DNA product that can be directly introduced by natural transformation. Selection for the introduced antibiotic resistance marker yields the deletion of interest in a single step. Because these cassettes also contain FRT (FLP recognition target) sequences flanking the resistance marker, Flp recombinase can be used to generate an unmarked, in-frame deletion. We developed a similar methodology and tools for the rapid insertion of specific genes at a benign site in the chromosome for purposes such as complementation. Finally, we generated derivatives of these tools to facilitate different applications, such as inducible gene expression and assessing protein production. We demonstrated the utility of these tools by deleting and inserting genes known or predicted to be involved in motility. While developed for V. fischeri strain ES114, we anticipate that these tools can be adapted for use in other V. fischeri strains and, potentially, other microbes. IMPORTANCE Vibrio fischeri is a model organism for studying a variety of important processes, including symbiosis, biofilm formation, and quorum sensing. To facilitate investigation of these biological mechanisms, we developed approaches for rapidly generating deletions and insertions and demonstrated their utility using two genes of interest. The ease, consistency, and speed of the engineering is facilitated by a set of antibiotic resistance cassettes with common linker sequences that can be amplified by PCR with universal primers and fused to adjacent sequences using splicing by overlap extension and then introduced directly into V. fischeri , eliminating the need for cloning and plasmid conjugation. The antibiotic cassettes are flanked by FRT sequences, permitting their removal using Flp recombinase. We augmented these basic tools with a family of constructs for different applications. We anticipate that these tools will greatly accelerate mechanistic studies of biological processes in V. fischeri and potentially other Vibrio species.

scholarly journals Ambient pH Alters the Protein Content of Outer Membrane Vesicles, Driving Host Development in a Beneficial Symbiosis

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Jonathan B. Lynch ◽  
Julia A. Schwartzman ◽  
Brittany D. Bennett ◽  
Sarah J. McAnulty ◽  
Mirjam Knop ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Marine Bacterium ◽  
Vibrio Fischeri ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Dependent Manner ◽  
Acidic Ph ◽  
Content Type ◽  
Bacterial Physiology ◽  
Host Development

ABSTRACT Outer membrane vesicles (OMVs) are continuously produced by Gram-negative bacteria and are increasingly recognized as ubiquitous mediators of bacterial physiology. In particular, OMVs are powerful effectors in interorganismal interactions, driven largely by their molecular contents. These impacts have been studied extensively in bacterial pathogenesis but have not been well documented within the context of mutualism. Here, we examined the proteomic composition of OMVs from the marine bacterium Vibrio fischeri, which forms a specific mutualism with the Hawaiian bobtail squid, Euprymna scolopes. We found that V. fischeri upregulates transcription of its major outer membrane protein, OmpU, during growth at an acidic pH, which V. fischeri experiences when it transitions from its environmental reservoir to host tissues. We used comparative genomics and DNA pulldown analyses to search for regulators of ompU and found that differential expression of ompU is governed by the OmpR, H-NS, and ToxR proteins. This transcriptional control combines with nutritional conditions to govern OmpU levels in OMVs. Under a host-encountered acidic pH, V. fischeri OMVs become more potent stimulators of symbiotic host development in an OmpU-dependent manner. Finally, we found that symbiotic development could be stimulated by OMVs containing a homolog of OmpU from the pathogenic species Vibrio cholerae, connecting the role of a well-described virulence factor with a mutualistic element. This work explores the symbiotic effects of OMV variation, identifies regulatory machinery shared between pathogenic and mutualistic bacteria, and provides evidence of the role that OMVs play in animal-bacterium mutualism. IMPORTANCE Beneficial bacteria communicate with their hosts through a variety of means. These communications are often carried out by a combination of molecules that stimulate responses from the host and are necessary for development of the relationship between these organisms. Naturally produced bacterial outer membrane vesicles (OMVs) contain many of those molecules and can stimulate a wide range of responses from recipient organisms. Here, we describe how a marine bacterium, Vibrio fischeri, changes the makeup of its OMVs under conditions that it experiences as it goes from its free-living lifestyle to associating with its natural host, the Hawaiian bobtail squid. This work improves our understanding of how bacteria change their signaling profile as they begin to associate with their beneficial partner animals.

scholarly journals LitR Is a Repressor of syp Genes and Has a Temperature-Sensitive Regulatory Effect on Biofilm Formation and Colony Morphology in Vibrio (Aliivibrio) salmonicida

2014 ◽  
Vol 80 (17) ◽  
pp. 5530-5541 ◽  
Author(s):  
Hilde Hansen ◽  
Ane Mohn Bjelland ◽  
Maria Ronessen ◽  
Espen Robertsen ◽  
Nils Peder Willassen
Keyword(s):  
Biofilm Formation ◽  
Cold Water ◽  
Vibrio Fischeri ◽  
Seawater Temperature ◽  
Colony Morphology ◽  
Effective Vaccine ◽  
Temperature Sensitive ◽  
Regulatory Effect ◽  
Content Type ◽  
Fish Model

ABSTRACTVibrio(Aliivibrio)salmonicidais the etiological agent of cold water vibriosis, a disease in farmed Atlantic salmon (Salmo salar) that is kept under control due to an effective vaccine. A seawater temperature below 12°C is normally required for disease development. Quorum sensing (QS) is a cell density-regulated communication system that bacteria use to coordinate activities involved in colonization and pathogenesis, and we have previously shown that inactivation of the QS master regulator LitR attenuates theV. salmonicidastrain LFI1238 in a fish model. We show here that strain LFI1238 and a panel of naturally occurringV. salmonicidastrains are poor biofilm producers. Inactivation oflitRin the LFI1238 strain enhances medium- and temperature-dependent adhesion, rugose colony morphology, and biofilm formation. Chemical treatment and electron microscopy of the biofilm identified an extracellular matrix consisting mainly of a fibrous network, proteins, and polysaccharides. Further, by microarray analysis of planktonic and biofilm cells, we identified a number of genes regulated by LitR and, among these, were homologues of theVibrio fischerisymbiosis polysaccharide (syp) genes. Thesypgenes were regulated by LitR in both planktonic and biofilm lifestyle analyses. Disruption ofsypgenes in theV. salmonicidaΔlitRmutant alleviated adhesion, rugose colony morphology, and biofilm formation. Hence, LitR is a repressor ofsyptranscription that is necessary for expression of the phenotypes examined. The regulatory effect of LitR on colony morphology and biofilm formation is temperature sensitive and weak or absent at temperatures above the bacterium's upper threshold for pathogenicity.

scholarly journals Calcium-Responsive Diguanylate Cyclase CasA Drives Cellulose-Dependent Biofilm Formation and Inhibits Motility in Vibrio fischeri

mBio ◽  
2021 ◽  
Author(s):  
Alice H. Tischler ◽  
Michael E. Vanek ◽  
Natasha Peterson ◽  
Karen L. Visick
Keyword(s):  
Simple Model ◽  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Diguanylate Cyclase ◽  
Host Organism ◽  
Signaling Molecule ◽  
Content Type ◽  
Environmental Signal ◽  
Successful Colonization

Biofilm formation and motility are often critical behaviors for bacteria to colonize a host organism. Vibrio fischeri is the exclusive colonizer of its host’s symbiotic organ and requires both biofilm formation and motility to initiate successful colonization, providing a relatively simple model to explore complex behaviors. In this study, we determined how the environmental signal calcium alters bacterial behavior through production of the signaling molecule c-di-GMP.

scholarly journals CysK Plays a Role in Biofilm Formation and Colonization by Vibrio fischeri

2015 ◽  
Vol 81 (15) ◽  
pp. 5223-5234 ◽  
Author(s):  
Priyanka Singh ◽  
John F. Brooks ◽  
Valerie A. Ray ◽  
Mark J. Mandel ◽  
Karen L. Visick
Keyword(s):  
Colony Formation ◽  
Biofilm Formation ◽  
Parent Strain ◽  
Vibrio Fischeri ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Biosynthetic Genes ◽  
Content Type ◽  
Agar Surface ◽  
Control Activation

ABSTRACTA biofilm, or a matrix-embedded community of cells, promotes the ability of the bacteriumVibrio fischerito colonize its symbiotic host, the Hawaiian squidEuprymna scolopes. Biofilm formation and colonization depend onsyp, an 18-gene polysaccharide locus. To identify other genes necessary for biofilm formation, we screened for mutants that failed to form wrinkled colonies, a type of biofilm. We obtained several with defects in genes required for cysteine metabolism, includingcysH,cysJ,cysK, andcysN. ThecysKmutant exhibited the most severe wrinkling defect. It could be complemented with a wild-type copy of thecysKgene, which encodesO-acetylserine sulfhydrolase, or by supplementing the medium with additional cysteine. None of a number of other mutants defective for biosynthetic genes negatively impacted wrinkled colony formation, suggesting a specific role for CysK. CysK did not appear to control activation of Syp regulators or transcription of thesyplocus, but it did influence production of the Syp polysaccharide. Under biofilm-inducing conditions, thecysKmutant retained the same ability as that of the parent strain to adhere to the agar surface. ThecysKmutant also exhibited a defect in pellicle production that could be complemented by thecysKgene but not by cysteine, suggesting that, under these conditions, CysK is important for more than the production of cysteine. Finally, our data reveal a role forcysKin symbiotic colonization byV. fischeri. Although many questions remain, this work provides insights into additional factors required for biofilm formation and colonization byV. fischeri.

scholarly journals The Hybrid Sensor Kinase RscS Integrates Positive and Negative Signals To Modulate Biofilm Formation in Vibrio fischeri

2008 ◽  
Vol 190 (13) ◽  
pp. 4437-4446 ◽  
Author(s):  
Kati Geszvain ◽  
Karen L. Visick
Keyword(s):  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Transmembrane Helix ◽  
Bioinformatic Analysis ◽  
Colony Morphology ◽  
Sensor Kinase ◽  
Pas Domain ◽  
Transmembrane Helices ◽  
Pellicle Formation ◽  
Carboxy Terminal

ABSTRACT Overexpression of the Vibrio fischeri sensor kinase RscS induces expression of the syp (symbiosis polysaccharide) gene cluster and promotes biofilm phenotypes such as wrinkled colony morphology, pellicle formation, and surface adherence. RscS is predicted to be a hybrid sensor kinase with a histidine kinase/ATPase (HATPase) domain, a receiver (Rec) domain, and a histidine phosphotransferase (Hpt) domain. Bioinformatic analysis also revealed the following three potential signal detection domains within RscS: two transmembrane helices forming a transmembrane region (TMR), a large periplasmic (PP) domain, and a cytoplasmic PAS domain. In this work, we genetically dissected the contributions of these domains to RscS function. Substitutions within the carboxy-terminal domain supported identification of RscS as a hybrid sensor kinase; disruption of both the HATPase and Rec domains eliminated induction of syp transcription, wrinkled colony morphology, pellicle formation, and surface adherence, while disruption of Hpt resulted in decreased activity. The PAS domain was also critical for RscS activity; substitutions in PAS resulted in a loss of activity. Generation of a cytoplasmic, N-terminal deletion derivative of RscS resulted in a partial loss of activity, suggesting a role for localization to the membrane and/or sequences within the TMR and PP domain. Finally, substitutions within the first transmembrane helix of the TMR and deletions within the PP domain both resulted in increased activity. Thus, RscS integrates both inhibitory and stimulatory signals from the environment to regulate biofilm formation by V. fischeri.

scholarly journals Vibrio fischeri Biofilm Formation Prevented by a Trio of Regulators

2018 ◽  
Vol 84 (19) ◽  
Author(s):  
Cecilia M. Thompson ◽  
Anne E. Marsden ◽  
Alice H. Tischler ◽  
Jovanka Koo ◽  
Karen L. Visick
Keyword(s):  
Biofilm Formation ◽  
Vibrio Fischeri ◽  
Negative Control ◽  
Negative Regulators ◽  
Content Type ◽  
Genetically Manipulated ◽  
Biofilm Development ◽  
Matrix Control ◽  
Symbiosis Polysaccharide

ABSTRACT 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.

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