Significance Competition among cooccurring bacteria can change the structure and function of a microbial community. However, little is known about molecular mechanisms that impact such interactions in vivo. We used association between bioluminescent their squid host to study how environmentally transmitted compete for limited number colonization sites. Our work suggests Vibrio fischeri use type VI secretion system, acting as contact-dependent interbacterial “weapon,” eliminate competing...

ABSTRACT Swarming colonies of the bacterium Proteus mirabilis are capable self-recognition and territorial behavior. Swarms independent P. isolates can recognize each other as foreign establish a visible boundary where they meet; in contrast, genetically identical swarms merge. The ids genes, which encode self-identity proteins, necessary but not sufficient for this Here we have identified two new gene clusters: one ( idr ) encodes rhs -related products, another tss putative type VI...

In response to the in vivo environment, Salmonella enterica serovar Typhimurium lipopolysaccharide (LPS) is modified. These modifications are controlled part by two-component regulatory system PmrA-PmrB, with addition of 4-aminoarabinose (Ara4N) lipid A and phosphoethanolamine (pEtN) core. Here we demonstrate that PmrA-regulated STM4118 (cptA) gene necessary for pEtN LPS pmrC, a A, did not affect core addition. Although imparting similar surface charge modification as Ara4N, which greatly...

Symbiotic bacteria use diverse strategies to compete for host colonization sites. However, little is known about the environmental cues that modulate interbacterial competition as they transition between free-living and host-associated lifestyles. We used mutualistic relationship Eupyrmna scolopes squid Vibrio fischeri investigate how intraspecific regulated symbionts move from seawater a host-like environment. recently reported V. uses type VI secretion system (T6SS) during colonization....

Abstract Background The Salmonella PreA/PreB two-component system (TCS) is an ortholog of the QseBC TCS Escherichia coli . In both and E. , this has been shown to affect motility virulence in response quorum-sensing hormonal signals, transcription enterica serovar Typhimurium ( S Typhimurium) pmrAB operon, which encodes important virulence-associated TCS. Results To determine regulon Typhimurium, we performed DNA microarrays comparing wild type strain various preA and/or preB mutants...

The protein YfeX from Escherichia coli has been proposed to be essential for the process of iron removal heme by carrying out a dechelation without cleavage porphyrin macrocycle. Since this reaction is unique and would represent first instance biological heme, we undertook characterize YfeX. Our data reveal that effectively decolorizes dyes alizarin red Cibacron blue F3GA peroxidase activity with pyrogallal but not guiacol. oxidizes protoporphyrinogen protoporphyrin in vitro. However, were...

Photosynthetic carbon (C) fixation by phytoplankton in the Southern Ocean (SO) plays a critical role regulating air–sea exchange of dioxide and thus global climate. In SO, photosynthesis (PS) is often constrained low iron, temperatures, but highly variable light intensities. Recently, proton-pumping rhodopsins (PPRs) were identified marine phytoplankton, providing an alternate iron-free, light-driven source cellular energy. These proteins pump protons across membranes through absorption...

Bacteria employ antagonistic strategies to eliminate competitors of an ecological niche. Contact-dependent mechanisms, such as the type VI secretion system (T6SS), are prevalent in host-associated bacteria, yet we know relatively little about how T6SS+ strains make contact with highly viscous environments, host mucus. To better understand cells respond and one another performed a genome-wide transposon mutant screen T6SS-wielding beneficial bacterial symbiont,

ABSTRACT Functional studies of host-microbe interactions benefit from natural model systems that enable exploration molecular mechanisms at the interface. Bioluminescent Vibrio fischeri colonize light organ Hawaiian bobtail squid, Euprymna scolopes , and this binary has enabled advances in understanding communication, colonization specificity, vivo biofilms, intraspecific competition, quorum sensing. The hummingbird berryi, can be generationally bred maintained lab settings had multiple...

Abstract The type VI secretion system (T6SS) is a broadly distributed interbacterial weapon found in both beneficial and pathogenic bacteria can enhance microbe’s ability to colonize host. Vibrio fischeri symbiont of fish squid model organism for T6SS function, which activated high-viscosity conditions. Previously, we isolated an hns mutant transposon screen identify regulators the V. MJ11. gene encodes DNA-binding protein, H-NS, conserved global regulator expression that aids adaptation...

ABSTRACT What makes a bacterium pathogenic? Since the early days of germ theory, researchers have categorized bacteria as pathogens or non-pathogens, those that cause harm and do not, but this binary view is not always accurate. Vibrio fischeri an exclusive mutualistic symbiont found within light organs Hawaiian bobtail squid. This symbiotic interaction requires V. to utilize range behaviors produce molecules are often associated with pathogenicity. juxtaposition employing “pathogenic” for...

The experimental model of high-dose Leishmania mexicana infection is used frequently to study molecular mechanisms regulating Th2 response since most inbred mice regardless their genetic background display cytokine-dependent susceptibility L. unlike major. Here, we analyzed the course in BALB/c, C57BL/6 and CBA/J mouse strains using low-dose ear that mimics natural transmission. Although all three were equally susceptible back rump infection, they displayed marked differences ability control...

Summary Although it is accepted that bacteria‐colonizing host tissues are commonly faced with iron‐limiting conditions and pathogenic bacteria often utilize iron from host‐derived haem‐based compounds, the mechanisms of acquisition by beneficial symbiotic less clear. The bacterium Vibrio fischeri mutualistically colonizes light organ squid Euprymna scolopes . Genome sequence analysis V. revealed a putative haem‐uptake gene cluster, through mutant we confirmed this cluster important for...

Interbacterial competition is prevalent in host-associated microbiota, where it can shape community structure and function, impacting host health both positive negative ways. However, the factors that permit bacteria to discriminate among their various neighbors for targeted elimination of competitors remain elusive. We identified a putative lipoprotein (TasL) Vibrio species mediates cell-cell attachment with subset target strains, allowing inhibitors specific elimination. Here, we describe...

Vibrio fischeri serves as a valuable model of bacterial bioluminescence, its regulation, and functional significance. Light output varies more than 10,000-fold in wild-type isolates from different environments, yet dim bright strains have similar organization the light-producing lux genes, with activator-encoding luxR divergently transcribed luxICDABEG. By comparing genomes strain MJ11 dimmer ES114, we found that region has diverged most shared orthologs, including those flanking lux....

We announce the complete genome sequence for Proteus mirabilis strain BB2000, a model system self recognition. This opportunistic pathogen contains single, circular chromosome (3,846,754 bp). Comparisons between this and that of HI4320 reveal genetic variations corresponding to previously unknown physiological self-recognition differences.

The marine bacterium Vibrio fischeri efficiently colonizes its symbiotic squid host, Euprymna scolopes, by producing a transient biofilm dependent on the symbiosis polysaccharide (SYP). In vitro, however, wild-type strain ES114 fails to form SYP-dependent biofilms. Instead, genetically engineered strains, such as those lacking negative regulator BinK, have been developed study this phenomenon. Historically, V. has grown using LBS, complex medium containing tryptone and yeast extract;...

Abstract The type VI secretion system (T6SS) is an interbacterial weapon composed of thousands protein subunits and predicted to require significant cellular energy deploy, yet a fitness cost from T6SS use rarely observed. Here, we identify host-like conditions where the incurs using beneficial symbiont, Vibrio fischeri , which uses its eliminate competitors in natural squid host. We hypothesized that for could be dependent on energetic state used theoretical ATP estimates predict when...

Bacterial pheromone signaling is often governed both by environmentally responsive regulators and positive feedback. This regulatory combination has the potential to coordinate a group response among distinct subpopulations that perceive key environmental stimuli differently. We have explored interplay between an regulator pheromone-mediated feedback in intercellular Vibrio fischeri ES114, bioluminescent bacterium colonizes squid Euprymna scolopes. Bioluminescence ES114 controlled part...

The PmrA/PmrB two-component system encoded by the pmrCAB operon regulates modification of Salmonella enterica serovar Typhimurium lipopolysaccharide leading to polymyxin B resistance. PmrA and PhoP are only known activators pmrCAB. A transposon mutagenesis screen for additional regulators a pmrC::MudJ fusion led identification system, termed PreA/PreB (pmrCAB B), that controls transcription in response unknown signals. initial observations indicated insertions in, or deletion of, preB...

Bacteria employ diverse competitive strategies to enhance fitness and promote their own propagation. However, little is known about how symbiotic bacteria modulate mechanisms as they compete for a host niche. The bacterium Vibrio fischeri forms relationship with marine animals encodes type VI secretion system (T6SS), which contact-dependent killing mechanism used eliminate competitors during colonization of the Euprymna scolopes squid light organ. Like other horizontally acquired symbionts,...

The type VI secretion system (T6SS) is widely distributed in diverse bacterial species and habitats where it required for interbacterial competition interactions with eukaryotic cells. Previous work described the role of a T6SS beneficial symbiont, Vibrio fischeri, during colonization light organ Euprymna scolopes squid. However, prevalence diversity T6SSs found within distinct symbiotic structures this model host have not yet been determined. Here, we analyzed 73 genomes isolates from squid...

ABSTRACT Bacteria often use pheromones to coordinate group behaviors in specific environments. While high cell density is required for achieve stimulatory levels, environmental cues can also influence pheromone accumulation and signaling. For the squid symbiont Vibrio fischeri ES114, bioluminescence requires pheromone-mediated regulation, this signaling induced host a greater extent than culture, even at an equivalent density. Our goal better understand environment-specific control over...

The Gac/Csr regulatory system is conserved throughout the γ-proteobacteria and controls key pathways in central carbon metabolism, quorum sensing, biofilm formation virulence important plant animal pathogens. Here we show that elevated intracellular citrate levels a Vibrio fischeri aconitase mutant correlate with activation of cascade induction bright luminescence. Spontaneous or directed mutations gene encodes synthase reversed luminescence mutants, eliminated their accumulation expression...