Vibrio fischeri Metabolism

Dunn, Anne K.

doi:10.1016/b978-0-12-394423-8.00002-0

Cited by 32 publications

(30 citation statements)

References 128 publications

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“…The remaining symbiont cells repopulate the light organ within hours, by growing on substrates including amino acids and glycerophospholipids (23,24), eventually providing the squid's nocturnal bioluminescence. Light emission, which requires oxygen (32), is highest during the night (33). In the fully developed light organ, where the symbionts are oxygen limited (24,33), the diel bioluminescent rhythm is potentiated by an acidic crypt environment, which creates a Bohr effect that releases oxygen from the carrier protein, hemocyanin (34).…”

Section: Significancementioning

confidence: 99%

The chemistry of negotiation: Rhythmic, glycan-driven acidification in a symbiotic conversation

Schwartzman

Koch

Heath‐Heckman

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

113

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Glycans have emerged as critical determinants of immune maturation, microbial nutrition, and host health in diverse symbioses. In this study, we asked how cyclic delivery of a single host-derived glycan contributes to the dynamic stability of the mutualism between the squid Euprymna scolopes and its specific, bioluminescent symbiont, Vibrio fischeri. V. fischeri colonizes the crypts of a host organ that is used for behavioral light production. E. scolopes synthesizes the polymeric glycan chitin in macrophage-like immune cells called hemocytes. We show here that, just before dusk, hemocytes migrate from the vasculature into the symbiotic crypts, where they lyse and release particulate chitin, a behavior that is established only in the mature symbiosis. Diel transcriptional rhythms in both partners further indicate that the chitin is provided and metabolized only at night. A V. fischeri mutant defective in chitin catabolism was able to maintain a normal symbiont population level, but only until the symbiotic organ reached maturity (∼4 wk after colonization); this result provided a direct link between chitin utilization and symbiont persistence. Finally, catabolism of chitin by the symbionts was also specifically required for a periodic acidification of the adult crypts each night. This acidification, which increases the level of oxygen available to the symbionts, enhances their capacity to produce bioluminescence at night. We propose that other animal hosts may similarly regulate the activities of epithelium-associated microbial communities through the strategic provision of specific nutrients, whose catabolism modulates conditions like pH or anoxia in their symbionts' habitat.symbiosis | squid-vibrio | metabolism | chitin

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Section: Significancementioning

confidence: 99%

The chemistry of negotiation: Rhythmic, glycan-driven acidification in a symbiotic conversation

Schwartzman

Koch

Heath‐Heckman

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

113

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“…An effort is under way to generate a defined mutant library for Vibrio fischeri (11), a genetically tractable organism studied for its bioluminescence (12,13), cell-cell signaling (14)(15)(16), interesting physiology (17,18), biofilm formation (19)(20)(21)(22), and light organ symbiosis with the Hawaiian bobtail squid Euprymna scolopes (23)(24)(25)(26). Both this insertion mutant library, which is based on a mini-Tn5 transposon (27), and a recent complementary mariner-based InSeq study with V. fischeri (28) involve selection on LBS medium (29), which is a Tris-buffered high-NaCl derivative of LB (containing [per liter] 10 g of tryptone, 5 g of yeast extract, 20 g of NaCl, and 50 mM Tris [pH 7.5]).…”

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confidence: 99%

An Expanded Transposon Mutant Library Reveals that Vibrio fischeri δ-Aminolevulinate Auxotrophs Can Colonize Euprymna scolopes

Lyell

Septer

Dunn

et al. 2017

Appl Environ Microbiol

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Libraries of defined mutants are valuable research tools but necessarily lack gene knockouts that are lethal under the conditions used in library construction. In this study, we augmented a Vibrio fischeri mutant library generated on a rich medium (LBS, which contains [per liter] 10 g of tryptone, 5 g of yeast extract, 20 g of NaCl, and 50 mM Tris [pH 7.5]) by selecting transposon insertion mutants on supplemented LBS and screening for those unable to grow on LBS. We isolated strains with insertions in alr, glr (murI), glmS, several heme biosynthesis genes, and ftsA, as well as a mutant disrupted 14 bp upstream of ftsQ. Mutants with insertions in ftsA or upstream of ftsQ were recovered by addition of Mg 2ϩ to LBS, but their cell morphology and motility were affected. The ftsA mutant was more strongly affected and formed cells or chains of cells that appeared to wind back on themselves helically. Growth of mutants with insertions in glmS, alr, or glr was recovered with N-acetylglucosamine (NAG), D-alanine, or D-glutamate, respectively. We hypothesized that NAG, D-alanine, or D-glutamate might be available to V. fischeri in the Euprymna scolopes light organ; however, none of these mutants colonized the host effectively. In contrast, hemA and hemL mutants, which are auxotrophic for ␦-aminolevulinate (ALA), colonized at wild-type levels, although mutants later in the heme biosynthetic pathway were severely impaired or unable to colonize. Our findings parallel observations that legume hosts provide Bradyrhizobium symbionts with ALA, but they contrast with virulence phenotypes of hemA mutants in some pathogens. The results further inform our understanding of the symbiotic light organ environment.IMPORTANCE By supplementing a rich yeast-based medium, we were able to recover V. fischeri mutants with insertions in conditionally essential genes, and further characterization of these mutants provided new insights into this bacterium's symbiotic environment. Most notably, we show evidence that the squid host can provide V. fischeri with enough ALA to support its growth in the light organ, paralleling the finding that legumes provide Bradyrhizobium ALA in symbiotic nodules. Taken together, our results show how a simple method of augmenting already rich media can expand the reach and utility of defined mutant libraries.KEYWORDS Photobacterium, Aliivibrio, symbiosis, aminolevulinic acid, hemin, photobacteria D efined knockout mutant libraries are useful resources that have been generated to promote research in several bacterial experimental models and pathogens (1-10). In such studies, researchers have often listed essential genes, the knockouts of which were apparently lethal under the conditions of library construction and therefore not represented by mutants in the library. In order to recover insertion mutants collectively

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“…Frequently, AHL QS allows opportunistic pathogens and symbionts to sense and respond to lifestyle shifts that occur as a bacterium cycles between a free-living (low-population-density) state and a host-associated (high-population-density) state (12)(13)(14)(15). In fact, QS is important for the virulence of many species (16).…”

mentioning

confidence: 99%

Cross-Species Comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei Quorum-Sensing Regulons

et al. 2014

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c Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei (the Bptm group) are close relatives with very different lifestyles: B. pseudomallei is an opportunistic pathogen, B. thailandensis is a nonpathogenic saprophyte, and B. mallei is a host-restricted pathogen. The acyl-homoserine lactone quorum-sensing (QS) systems of these three species show a high level of conservation. We used transcriptome sequencing (RNA-seq) to define the quorum-sensing regulon in each species, and we performed a cross-species analysis of the QS-controlled orthologs. Our analysis revealed a core set of QS-regulated genes in all three species, as well as QS-controlled factors shared by only two species or unique to a given species. This global survey of the QS regulons of B. pseudomallei, B. thailandensis, and B. mallei serves as a platform for predicting which QS-controlled processes might be important in different bacterial niches and contribute to the pathogenesis of B. pseudomallei and B. mallei.

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Vibrio fischeri Metabolism

Cited by 32 publications

References 128 publications

The chemistry of negotiation: Rhythmic, glycan-driven acidification in a symbiotic conversation

The chemistry of negotiation: Rhythmic, glycan-driven acidification in a symbiotic conversation

An Expanded Transposon Mutant Library Reveals that Vibrio fischeri δ-Aminolevulinate Auxotrophs Can Colonize Euprymna scolopes

Cross-Species Comparison of the Burkholderia pseudomallei, Burkholderia thailandensis, and Burkholderia mallei Quorum-Sensing Regulons

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