scholarly journals Population Dynamics of Vibrio fischeri during Infection of Euprymna scolopes

2003 ◽  
Vol 69 (10) ◽  
pp. 5928-5934 ◽  
Author(s):  
Jessica McCann ◽  
Eric V. Stabb ◽  
Deborah S. Millikan ◽  
Edward G. Ruby
Keyword(s):  
Population Dynamics ◽  
Vibrio Fischeri ◽  
Single Copy ◽  
Bacterial Cells ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Luminous Bacterium ◽  
Ambient Seawater ◽  
Light Emitting ◽  
Low Concentrations

ABSTRACT The luminous bacterium Vibrio fischeri colonizes a specialized light-emitting organ within its squid host, Euprymna scolopes. Newly hatched juvenile squid must acquire their symbiont from ambient seawater, where the bacteria are present at low concentrations. To understand the population dynamics of V. fischeri during colonization more fully, we used mini-Tn7 transposons to mark bacteria with antibiotic resistance so that the growth of their progeny could be monitored. When grown in culture, there was no detectable metabolic burden on V. fischeri cells carrying the transposon, which inserts in single copy in a specific intergenic region of the V. fischeri genome. Strains marked with mini-Tn7 also appeared to be equivalent to the wild type in their ability to infect and multiply within the host during coinoculation experiments. Studies of the early stages of colonization suggested that only a few bacteria became associated with symbiotic tissue when animals were exposed for a discrete period (3 h) to an inoculum of V. fischeri cells equivalent to natural population levels; nevertheless, all these hosts became infected. When three differentially marked strains of V. fischeri were coincubated with juvenile squid, the number of strains recovered from an individual symbiotic organ was directly dependent on the size of the inoculum. Further, these results indicated that, when exposed to low numbers of V. fischeri, the host may become colonized by only one or a few bacterial cells, suggesting that symbiotic infection is highly efficient.

scholarly journals Squid-Derived Chitin Oligosaccharides Are a Chemotactic Signal during Colonization by Vibrio fischeri

2012 ◽  
Vol 78 (13) ◽  
pp. 4620-4626 ◽  
Author(s):  
Mark J. Mandel ◽  
Amy L. Schaefer ◽  
Caitlin A. Brennan ◽  
Elizabeth A. C. Heath-Heckman ◽  
Cindy R. DeLoney-Marino ◽  
...  
Keyword(s):  
Vibrio Fischeri ◽  
Attachment Site ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Luminous Bacterium ◽  
Content Type ◽  
Light Emitting ◽  
Marine Luminous Bacterium ◽  
The Family ◽  
Host Generation

ABSTRACTChitin, a polymer ofN-acetylglucosamine (GlcNAc), is noted as the second most abundant biopolymer in nature. Chitin serves many functions for marine bacteria in the familyVibrionaceae(“vibrios”), in some instances providing a physical attachment site, inducing natural genetic competence, and serving as an attractant for chemotaxis. The marine luminous bacteriumVibrio fischeriis the specific symbiont in the light-emitting organ of the Hawaiian bobtail squid,Euprymna scolopes. The bacterium provides the squid with luminescence that the animal uses in an antipredatory defense, while the squid supports the symbiont's nutritional requirements.V. fischericells are harvested from seawater during each host generation, andV. fischeriis the only species that can complete this process in nature. Furthermore, chitin is located in squid hemocytes and plays a nutritional role in the symbiosis. We demonstrate here that chitin oligosaccharides produced by the squid host serve as a chemotactic signal for colonizing bacteria.V. fischeriuses the gradient of host chitin to enter the squid light organ duct and colonize the animal. We provide evidence that chitin serves a novel function in an animal-bacterial mutualism, as an animal-produced bacterium-attracting synomone.

scholarly journals FlrA, a σ54-Dependent Transcriptional Activator in Vibrio fischeri, Is Required for Motility and Symbiotic Light-Organ Colonization

2003 ◽  
Vol 185 (12) ◽  
pp. 3547-3557 ◽  
Author(s):  
Deborah S. Millikan ◽  
Edward G. Ruby
Keyword(s):  
Vibrio Fischeri ◽  
Transcriptional Activator ◽  
Pcr Analysis ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Flagellar Regulon ◽  
Colonization Factors ◽  
Recognition Motifs ◽  
Arbitrarily Primed Pcr ◽  
Organ Colonization

ABSTRACT Flagellum-mediated motility of Vibrio fischeri is an essential factor in the bacterium's ability to colonize its host, the Hawaiian squid Euprymna scolopes. To begin characterizing the nature of the flagellar regulon, we have cloned a gene, designated flrA, from V. fischeri that encodes a putative σ54-dependent transcriptional activator. Genetic arrangement of the flrA locus in V. fischeri is similar to motility master-regulator operons of Vibrio cholerae and Vibrio parahaemolyticus. In addition, examination of regulatory regions of a number of flagellar operons in V. fischeri revealed apparent σ54 recognition motifs, suggesting that the flagellar regulatory hierarchy is controlled by a similar mechanism to that described in V. cholerae. However, in contrast to its closest known relatives, flrA mutant strains of V. fischeri ES114 were completely abolished in swimming capability. Although flrA provided in trans restored motility to the flrA mutant, the complemented strain was unable to reach wild-type levels of symbiotic colonization in juvenile squid, suggesting a possible role for the proper expression of FlrA in regulating symbiotic colonization factors in addition to those required for motility. Comparative RNA arbitrarily primed PCR analysis of the flrA mutant and its wild-type parent revealed several differentially expressed transcripts. These results define a regulon that includes both flagellar structural genes and other genes apparently not involved in flagellum elaboration or function. Thus, the transcriptional activator FlrA plays an essential role in regulating motility, and apparently in modulating other symbiotic functions, in V. fischeri.

scholarly journals Dominance of Vibrio fischeri in Secreted Mucus outside the Light Organ of Euprymna scolopes: the First Site of Symbiont Specificity

2003 ◽  
Vol 69 (7) ◽  
pp. 3932-3937 ◽  
Author(s):  
Spencer V. Nyholm ◽  
Margaret J. McFall-Ngai
Keyword(s):  
Fluorescent Protein ◽  
Vibrio Fischeri ◽  
Signal Molecules ◽  
Natural Seawater ◽  
Gram Negative Bacteria ◽  
Light Organ ◽  
Bacterial Cells ◽  
Euprymna Scolopes ◽  
Gram Negative ◽  
Green Fluorescent

ABSTRACT Previous studies of the Euprymna scolopes-Vibrio fischeri symbiosis have demonstrated that, during colonization, the hatchling host secretes mucus in which gram-negative environmental bacteria amass in dense aggregations outside the sites of infection. In this study, experiments with green fluorescent protein-labeled symbiotic and nonsymbiotic species of gram-negative bacteria were used to characterize the behavior of cells in the aggregates. When hatchling animals were exposed to 103 to 106 V. fischeri cells/ml added to natural seawater, which contains a mix of approximately 106 nonspecific bacterial cells/ml, V. fischeri cells were the principal bacterial cells present in the aggregations. Furthermore, when animals were exposed to equal cell numbers of V. fischeri (either a motile or a nonmotile strain) and either Vibrio parahaemolyticus or Photobacterium leiognathi, phylogenetically related gram-negative bacteria that also occur in the host's habitat, the symbiont cells were dominant in the aggregations. The presence of V. fischeri did not compromise the viability of these other species in the aggregations, and no significant growth of V. fischeri cells was detected. These findings suggested that dominance results from the ability of V. fischeri either to accumulate or to be retained more effectively within the mucus. Viability of the V. fischeri cells was required for both the formation of tight aggregates and their dominance in the mucus. Neither of the V. fischeri quorum-sensing compounds accumulated in the aggregations, which suggested that the effects of these small signal molecules are not critical to V. fischeri dominance. Taken together, these data provide evidence that the specificity of the squid-vibrio symbiosis begins early in the interaction, in the mucus where the symbionts aggregate outside of the light organ.

scholarly journals Vibrio fischeri Flagellin A Is Essential for Normal Motility and for Symbiotic Competence during Initial Squid Light Organ Colonization

2004 ◽  
Vol 186 (13) ◽  
pp. 4315-4325 ◽  
Author(s):  
Deborah S. Millikan ◽  
Edward G. Ruby
Keyword(s):  
Vibrio Fischeri ◽  
Complex Structure ◽  
Immunoblot Analysis ◽  
Soft Agar ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Mixed Inoculum ◽  
Mutant Cells ◽  
Organ Colonization

ABSTRACT The motile bacterium Vibrio fischeri is the specific bacterial symbiont of the Hawaiian squid Euprymna scolopes. Because motility is essential for initiating colonization, we have begun to identify stage-specific motility requirements by creating flagellar mutants that have symbiotic defects. V. fischeri has six flagellin genes that are uniquely arranged in two chromosomal loci, flaABCDE and flaF. With the exception of the flaA product, the predicted gene products are more similar to each other than to flagellins of other Vibrio species. Immunoblot analysis indicated that only five of the six predicted proteins were present in purified flagella, suggesting that one protein, FlaF, is unique with respect to either its regulation or its function. We created mutations in two genes, flaA and flaC. Compared to a flaC mutant, which has wild-type flagellation, a strain having a mutation in the flaA gene has fewer flagella per cell and exhibits a 60% decrease in its rate of migration in soft agar. During induction of light organ symbiosis, colonization by the flaA mutant is impaired, and this mutant is severely outcompeted when it is presented to the animal as a mixed inoculum with the wild-type strain. Furthermore, flaA mutant cells are preferentially expelled from the animal, suggesting either that FlaA plays a role in adhesion or that normal motility is an advantage for retention within the host. Taken together, these results show that the flagellum of V. fischeri is a complex structure consisting of multiple flagellin subunits, including FlaA, which is essential both for normal flagellation and for motility, as well as for effective symbiotic colonization.

scholarly journals RscS Functions Upstream of SypG To Control the syp Locus and Biofilm Formation in Vibrio fischeri

2008 ◽  
Vol 190 (13) ◽  
pp. 4576-4583 ◽  
Author(s):  
Elizabeth A. Hussa ◽  
Cynthia L. Darnell ◽  
Karen L. Visick
Keyword(s):  
Biofilm Formation ◽  
Large Scale ◽  
Vibrio Fischeri ◽  
Response Regulator ◽  
Bacterial Cells ◽  
Euprymna Scolopes ◽  
Regulatory Pathways ◽  
Two Component ◽  
Two Component Signal Transduction ◽  
Symbiosis Polysaccharide

ABSTRACTTwo-component signal transduction systems, composed of sensor kinase (SK) and response regulator (RR) proteins, allow bacterial cells to adapt to changes such as environmental flux or the presence of a host. RscS is an SK required forVibrio fischerito initiate a symbiotic partnership with the Hawaiian squidEuprymna scolopes, likely due to its role in controlling the symbiosis polysaccharide (syp) genes and thus biofilm formation. To determine which RR(s) functions downstream of RscS, we performed epistasis experiments with a library of 35 RR mutants. We found that several RRs contributed to RscS-mediated biofilm formation inV. fischeri. However, only thesyp-encoded symbiosis regulator SypG was required for both biofilm phenotypes andsyptranscription induced by RscS. These data support the hypothesis that RscS functions upstream of SypG to induce biofilm formation. In addition, this work also revealed a role for thesyp-encoded RR SypE in biofilm formation. To our knowledge, no other study has used a large-scale epistasis approach to elucidate two-component signaling pathways. Therefore, this work both contributes to our understanding of regulatory pathways important for symbiotic colonization byV. fischeriand establishes a paradigm for evaluating two-component pathways in the genomics era.

scholarly journals Independent host- and bacterium-based determinants protect a model symbiosis from phage predation

2021 ◽  
Author(s):  
Jonathan B Lynch ◽  
Brittany D Bennett ◽  
Bryan D Merrill ◽  
Edward G Ruby ◽  
Andrew J Hryckowian
Keyword(s):  
Extracellular Matrix ◽  
Microbial Communities ◽  
Marine Bacterium ◽  
Vibrio Fischeri ◽  
Euprymna Scolopes ◽  
Ambient Seawater ◽  
Bacterial Populations ◽  
Microbial Ecosystems ◽  
Shed Light

Bacteriophages (phages) are diverse and abundant constituents of microbial communities worldwide, and are capable of modulating bacterial populations in diverse ways. Here we describe a novel phage, ϕHNL01, which infects the marine bacterium Vibrio fischeri. We use culture-based approaches to demonstrate that mutations in the exopolysaccharide locus of V. fischeri render this bacterium resistant to infection by ϕHNL01, highlighting the extracellular matrix as a key determinant of phage tropism in this interaction. Additionally, using the natural symbiosis between V. fischeri and the squid Euprymna scolopes, we show that during colonization, V. fischeri is protected from phage present in the ambient seawater. Taken together, these findings shed light on independent yet synergistic host- and bacterium-based strategies for resisting symbiosis-disrupting phage predation, and present important implications for understanding these strategies in the context of host-associated microbial ecosystems.

scholarly journals Role for cheR of Vibrio fischeri in the Vibrio–squid symbiosis

2012 ◽  
Vol 58 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Cindy R. DeLoney-Marino ◽  
Karen L. Visick
Keyword(s):  
Marine Bacterium ◽  
Wild Type Strain ◽  
Vibrio Fischeri ◽  
Bacterial Motility ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Acetylneuraminic Acid ◽  
Symbiotic Partner ◽  
Fourfold Excess

Upon hatching, the Hawaiian squid Euprymna scolopes is rapidly colonized by its symbiotic partner, the bioluminescent marine bacterium Vibrio fischeri . Vibrio fischeri cells present in the seawater enter the light organ of juvenile squid in a process that requires bacterial motility. In this study, we investigated the role chemotaxis may play in establishing this symbiotic colonization. Previously, we reported that V. fischeri migrates toward numerous attractants, including N-acetylneuraminic acid (NANA), a component of squid mucus. However, whether or not migration toward an attractant such as squid-derived NANA helps the bacterium to localize toward the light organ is unknown. When tested for the ability to colonize juvenile squid, a V. fischeri chemotaxis mutant defective for the methyltransferase CheR was outcompeted by the wild-type strain in co-inoculation experiments, even when the mutant was present in fourfold excess. Our results suggest that the ability to perform chemotaxis is an advantage during colonization, but not essential.

scholarly journals Bactericidal Permeability-Increasing Proteins Shape Host-Microbe Interactions

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Fangmin Chen ◽  
Benjamin C. Krasity ◽  
Suzanne M. Peyer ◽  
Sabrina Koehler ◽  
Edward G. Ruby ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Vibrio Fischeri ◽  
Molecular Characteristics ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Lipopolysaccharide Binding Protein ◽  
Ambient Seawater ◽  
Microbe Interactions ◽  
Acidic Conditions ◽  
Host Microbe Interactions

ABSTRACT We characterized bactericidal permeability-increasing proteins (BPIs) of the squid Euprymna scolopes , EsBPI2 and EsBPI4. They have molecular characteristics typical of other animal BPIs, are closely related to one another, and nest phylogenetically among invertebrate BPIs. Purified EsBPIs had antimicrobial activity against the squid’s symbiont, Vibrio fischeri , which colonizes light organ crypt epithelia. Activity of both proteins was abrogated by heat treatment and coincubation with specific antibodies. Pretreatment under acidic conditions similar to those during symbiosis initiation rendered V. fischeri more resistant to the antimicrobial activity of the proteins. Immunocytochemistry localized EsBPIs to the symbiotic organ and other epithelial surfaces interacting with ambient seawater. The proteins differed in intracellular distribution. Further, whereas EsBPI4 was restricted to epithelia, EsBPI2 also occurred in blood and in a transient juvenile organ that mediates hatching. The data provide evidence that these BPIs play different defensive roles early in the life of E. scolopes , modulating interactions with the symbiont. IMPORTANCE This study describes new functions for bactericidal permeability-increasing proteins (BPIs), members of the lipopolysaccharide-binding protein (LBP)/BPI protein family. The data provide evidence that these proteins play a dual role in the modulation of symbiotic bacteria. In the squid-vibrio model, these proteins both control the symbiont populations in the light organ tissues where symbiont cells occur in dense monoculture and, concomitantly, inhibit the symbiont from colonizing other epithelial surfaces of the animal.

scholarly journals Role for Phosphoglucomutase in Vibrio fischeri-Euprymna scolopes Symbiosis

2002 ◽  
Vol 184 (18) ◽  
pp. 5121-5129 ◽  
Author(s):  
Cindy R. DeLoney ◽  
Therese M. Bartley ◽  
Karen L. Visick
Keyword(s):  
Vibrio Fischeri ◽  
Euprymna Scolopes ◽  
Wild Type ◽  
Galactose Metabolism ◽  
High Sequence Identity ◽  
E Coli ◽  
New Gene ◽  
Increased Sensitivity ◽  
Colonization Ability ◽  
Galactose Utilization

ABSTRACT Vibrio fischeri, a luminescent marine bacterium, specifically colonizes the light organ of its symbiotic partner, the Hawaiian squid Euprymna scolopes. In a screen for V. fischeri colonization mutants, we identified a strain that exhibited on average a 10-fold decrease in colonization levels relative to that achieved by wild-type V. fischeri. Further characterization revealed that this defect did not result from reduced luminescence or motility, two processes required for normal colonization. We determined that the transposon in this mutant disrupted a gene with high sequence identity to the pgm (phosphoglucomutase) gene of Escherichia coli, which encodes an enzyme that functions in both galactose metabolism and the synthesis of UDP-glucose. The V. fischeri mutant grew poorly with galactose as a sole carbon source and was defective for phosphoglucomutase activity, suggesting functional identity between E. coli Pgm and the product of the V. fischeri gene, which was therefore designated pgm. In addition, lipopolysaccharide profiles of the mutant were distinct from that of the parent strain and the mutant exhibited increased sensitivity to various cationic agents and detergents. Chromosomal complementation with the wild-type pgm allele restored the colonization ability to the mutant and also complemented the other noted defects. Unlike the pgm mutant, a galactose-utilization mutant (galK) of V. fischeri colonized juvenile squid to wild-type levels, indicating that the symbiotic defect of the pgm mutant is not due to an inability to catabolize galactose. Thus, pgm represents a new gene required for promoting colonization of E. scolopes by V. fischeri.

scholarly journals Vibrio fischeri lux Genes Play an Important Role in Colonization and Development of the Host Light Organ

2000 ◽  
Vol 182 (16) ◽  
pp. 4578-4586 ◽  
Author(s):  
Karen L. Visick ◽  
Jamie Foster ◽  
Judith Doino ◽  
Margaret McFall-Ngai ◽  
Edward G. Ruby
Keyword(s):  
Epithelial Cells ◽  
Light Emission ◽  
Vibrio Fischeri ◽  
Regulatory Proteins ◽  
Light Organ ◽  
Euprymna Scolopes ◽  
Light Emitting ◽  
Bioluminescent Bacterium ◽  
Lux Genes

ABSTRACT The bioluminescent bacterium Vibrio fischeri and juveniles of the squid Euprymna scolopes specifically recognize and respond to one another during the formation of a persistent colonization within the host's nascent light-emitting organ. The resulting fully developed light organ contains brightly luminescing bacteria and has undergone a bacterium-induced program of tissue differentiation, one component of which is a swelling of the epithelial cells that line the symbiont-containing crypts. While the luminescence (lux) genes of symbiotic V. fischeri have been shown to be highly induced within the crypts, the role of these genes in the initiation and persistence of the symbiosis has not been rigorously examined. We have constructed and examined three mutants (luxA, luxI, andluxR), defective in either luciferase enzymatic or regulatory proteins. All three are unable to induce normal luminescence levels in the host and, 2 days after initiating the association, had a three- to fourfold defect in the extent of colonization. Surprisingly, these lux mutants also were unable to induce swelling in the crypt epithelial cells. Complementing, in trans, the defect in light emission restored both normal colonization capability and induction of swelling. We hypothesize that a diminished level of oxygen consumption by a luciferase-deficient symbiotic population is responsible for the reduced fitness of lux mutants in the light organ crypts. This study is the first to show that the capacity for bioluminescence is critical for normal cell-cell interactions between a bacterium and its animal host and presents the first examples of V. fischeri genes that affect normal host tissue development.

Sign in / Sign up

Export Citation Format

Share Document