Journal articles: 'Pseudoalteromonas tunicata'

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Mai-Prochnow, Anne, Flavia Evans, Doralyn Dalisay-Saludes, Sacha Stelzer, Suhelen Egan, Sally James, Jeremy S. Webb, and Staffan Kjelleberg. "Biofilm Development and Cell Death in the Marine Bacterium Pseudoalteromonas tunicata." Applied and Environmental Microbiology 70, no. 6 (June 2004): 3232–38. http://dx.doi.org/10.1128/aem.70.6.3232-3238.2004.

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ABSTRACT The newly described green-pigmented bacterium Pseudoalteromonas tunicata (D2) produces target-specific inhibitory compounds against bacteria, algae, fungi, and invertebrate larvae and is frequently found in association with living surfaces in the marine environment. As part of our studies on the ecology of P. tunicata and its interaction with marine surfaces, we examined the ability of P. tunicata to form biofilms under continuous culture conditions within the laboratory. P. tunicata biofilms exhibited a characteristic architecture consisting of differentiated microcolonies surrounded by water channels. Remarkably, we observed a repeatable pattern of cell death during biofilm development of P. tunicata, similar to that recently reported for biofilms of Pseudomonas aeruginosa (J. S. Webb et al., J. Bacteriol. 185:4585-4595, 2003). Killing and lysis occurred inside microcolonies, apparently resulting in the formation of voids within these structures. A subpopulation of viable cells was always observed within the regions of killing in the biofilm. Moreover, extensive killing in mature biofilms appeared to result in detachment of the biofilm from the substratum. A novel 190-kDa autotoxic protein produced by P. tunicata, designated AlpP, was found to be involved in this biofilm killing and detachment. A ΔalpP mutant derivative of P. tunicata was generated, and this mutant did not show cell death during biofilm development. We propose that AlpP-mediated cell death plays an important role in the multicellular biofilm development of P. tunicata and subsequent dispersal of surviving cells within the marine environment.

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Rao, Dhana, Jeremy S. Webb, and Staffan Kjelleberg. "Competitive Interactions in Mixed-Species Biofilms Containing the Marine Bacterium Pseudoalteromonas tunicata." Applied and Environmental Microbiology 71, no. 4 (April 2005): 1729–36. http://dx.doi.org/10.1128/aem.71.4.1729-1736.2005.

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ABSTRACT Pseudoalteromonas tunicata is a biofilm-forming marine bacterium that is often found in association with the surface of eukaryotic organisms. It produces a range of extracellular inhibitory compounds, including an antibacterial protein (AlpP) thought to be beneficial for P. tunicata during competition for space and nutrients on surfaces. As part of our studies on the interactions between P. tunicata and the epiphytic bacterial community on the marine plant Ulva lactuca, we investigated the hypothesis that P. tunicata is a superior competitor compared with other bacteria isolated from the plant. A number of U. lactuca bacterial isolates were (i) identified by 16S rRNA gene sequencing, (ii) characterized for the production of or sensitivity to extracellular antibacterial proteins, and (iii) labeled with a fluorescent color tag (either the red fluorescent protein DsRed or green fluorescent protein). We then grew single- and mixed-species bacterial biofilms containing P. tunicata in glass flow cell reactors. In pure culture, all the marine isolates formed biofilms containing microcolony structures within 72 h. However, in mixed-species biofilms, P. tunicata removed the competing strain unless its competitor was relatively insensitive to AlpP (Pseudoalteromonas gracilis) or produced strong inhibitory activity against P. tunicata (Roseobacter gallaeciensis). Moreover, biofilm studies conducted with an AlpP− mutant of P. tunicata indicated that the mutant was less competitive when it was introduced into preestablished biofilms, suggesting that AlpP has a role during competitive biofilm formation. When single-species biofilms were allowed to form microcolonies before the introduction of a competitor, these microcolonies coexisted with P. tunicata for extended periods of time before they were removed. Two marine bacteria (R. gallaeciensis and P. tunicata) were superior competitors in this study. Our data suggest that this dominance can be attributed to the ability of these organisms to rapidly form microcolonies and their ability to produce extracellular antibacterial compounds.

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Franks, A., S. Egan, C. Holmstrï¿½m, S. James, H. Lappin-Scott, and S. Kjelleberg. "Inhibition of Fungal Colonization by Pseudoalteromonas tunicata Provides a Competitive Advantage during Surface Colonization." Applied and Environmental Microbiology 72, no. 9 (September 2006): 6079–87. http://dx.doi.org/10.1128/aem.00559-06.

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ABSTRACT The marine epiphytic bacterium Pseudoalteromonas tunicata produces a range of extracellular secondary metabolites that inhibit an array of common fouling organisms, including fungi. In this study, we test the hypothesis that the ability to inhibit fungi provides P. tunicata with an advantage during colonization of a surface. Studies on a transposon-generated antifungal-deficient mutant of P. tunicata, FM3, indicated that a long-chain fatty acid-coenzyme A ligase is involved in the production of a broad-range antifungal compound by P. tunicata. Flow cell experiments demonstrated that production of an antifungal compound provided P. tunicata with a competitive advantage against a marine yeast isolate during surface colonization. This compound enabled P. tunicata to disrupt an already established fungal biofilm by decreasing the number of yeast cells attached to the surface by 66% ï¿½ 9%. For in vivo experiments, the wild-type and FM3 strains of P. tunicata were used to inoculate the surface of the green alga Ulva australis. Double-gradient denaturing gradient gel electrophoresis analysis revealed that after 48 h, the wild-type P. tunicata had outcompeted the surface-associated fungal community, whereas the antifungal-deficient mutant had no effect on the fungal community. Our data suggest that P. tunicata is an effective competitor against fungal surface communities in the marine environment.

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Rao, Dhana, Jeremy S. Webb, Carola Holmström, Rebecca Case, Adrian Low, Peter Steinberg, and Staffan Kjelleberg. "Low Densities of Epiphytic Bacteria from the Marine Alga Ulva australis Inhibit Settlement of Fouling Organisms." Applied and Environmental Microbiology 73, no. 24 (October 26, 2007): 7844–52. http://dx.doi.org/10.1128/aem.01543-07.

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ABSTRACT Bacteria that produce inhibitory compounds on the surface of marine algae are thought to contribute to the defense of the host plant against colonization of fouling organisms. However, the number of bacterial cells necessary to defend against fouling on the plant surface is not known. Pseudoalteromonas tunicata and Phaeobacter sp. strain 2.10 (formerly Roseobacter gallaeciensis) are marine bacteria often found in association with the alga Ulva australis and produce a range of extracellular inhibitory compounds against common fouling organisms. P. tunicata and Phaeobacter sp. strain 2.10 biofilms with cell densities ranging from 102 to 108 cells cm−2 were established on polystyrene petri dishes. Attachment and settlement assays were performed with marine fungi (uncharacterized isolates from U. australis), marine bacteria (Pseudoalteromonas gracilis, Alteromonas sp., and Cellulophaga fucicola), invertebrate larvae (Bugula neritina), and algal spores (Polysiphonia sp.) and gametes (U. australis). Remarkably low cell densities (102 to 103 cells cm−2) of P. tunicata were effective in preventing settlement of algal spores and marine fungi in petri dishes. P. tunicata also prevented settlement of invertebrate larvae at densities of 104 to 105 cells cm−2. Similarly, low cell densities (103 to 104cells cm−2) of Phaeobacter sp. strain 2.10 had antilarval and antibacterial activity. Previously, it has been shown that abundance of P. tunicata on marine eukaryotic hosts is low (<1 × 103 cells cm−2) (T. L. Skovhus et al., Appl. Environ. Microbiol. 70:2373-2382, 2004). Despite such low numbers of P. tunicata on U. australis in situ, our data suggest that P. tunicata and Phaeobacter sp. strain 2.10 are present in sufficient quantities on the plant to inhibit fouling organisms. This strongly supports the hypothesis that P. tunicata and Phaeobacter sp. strain 2.10 can play a role in defense against fouling on U. australis at cell densities that commonly occur in situ.

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Dalisay, Doralyn S., Jeremy S. Webb, André Scheffel, Charles Svenson, Sally James, Carola Holmström, Suhelen Egan, and Staffan Kjelleberg. "A mannose-sensitive haemagglutinin (MSHA)-like pilus promotes attachment of Pseudoalteromonas tunicata cells to the surface of the green alga Ulva australis." Microbiology 152, no. 10 (October 1, 2006): 2875–83. http://dx.doi.org/10.1099/mic.0.29158-0.

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This study demonstrates that attachment of the marine bacterium Pseudoalteromonas tunicata to the cellulose-containing surface of the green alga Ulva australis is mediated by a mannose-sensitive haemagglutinin (MSHA-like) pilus. We have identified an MSHA pilus biogenesis gene locus in P. tunicata, termed mshI1I2JKLMNEGFBACDOPQ, which shows significant homology, with respect to its genetic characteristics and organization, to the MSHA pilus biogenesis gene locus of Vibrio cholerae. Electron microscopy studies revealed that P. tunicata wild-type cells express flexible pili peritrichously arranged on the cell surface. A P. tunicata mutant (SM5) with a transposon insertion in the mshJ region displayed a non-piliated phenotype. Using SM5, it has been demonstrated that the MSHA pilus promotes attachment of P. tunicata wild-type cells in polystyrene microtitre plates, as well as to microcrystalline cellulose and to the living surface of U. australis. P. tunicata also demonstrated increased pilus production in response to cellulose and its monomer constituent cellobiose. The MSHA pilus thus functions as a determinant of attachment in P. tunicata, and it is proposed that an understanding of surface sensing mechanisms displayed by P. tunicata will provide insight into specific ecological interactions that occur between this bacterium and higher marine organisms.

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Zhao, Chang-Hui, Jing-Jing Luo, Ting Gong, Xiang-Ling Huang, De-Zan Ye, and Zhu-Hua Luo. "Pseudoalteromonas xiamenensis sp. nov., a marine bacterium isolated from coastal surface seawater." International Journal of Systematic and Evolutionary Microbiology 64, Pt_2 (February 1, 2014): 444–48. http://dx.doi.org/10.1099/ijs.0.050229-0.

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A Gram-negative, oxidase- and catalase-positive, rod-shaped, non-spore-forming, motile, aerobic bacterium, designated Y2T, was isolated from surface seawater of Yundang Lake, Xiamen, China. The strain was able to grow in the presence of 0.5–6.0 % NaCl (optimum 1.0–1.5 %), at pH 5–10 (optimum pH 8) and at 10–40 °C (optimum 25 °C). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain Y2T belongs to the genus Pseudoalteromonas , with the highest sequence similarity of 94.9 % to Pseudoalteromonas tunicata D2T; within the genus Pseudoalteromonas , it showed the lowest similarity of 92.8 % to Pseudoalteromonas denitrificans ATCC 43337T. The G+C content of the chromosomal DNA of strain Y2T was 45.1 mol%. The predominant fatty acids were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0, C12 : 0 3-OH and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The only respiratory quinone detected was Q-8. Based on the phylogenetic and phenotypic characteristics, strain Y2T represents a novel species of the genus Pseudoalteromonas , for which the name Pseudoalteromonas xiamenensis sp. nov. is proposed; the type strain is Y2T ( = CGMCC 1.12157T = JCM 18779T).

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Egan, Suhelen, Sally James, Carola Holmstrom, and Staffan Kjelleberg. "Correlation between pigmentation and antifouling compounds produced by Pseudoalteromonas tunicata." Environmental Microbiology 4, no. 8 (August 2002): 433–42. http://dx.doi.org/10.1046/j.1462-2920.2002.00322.x.

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HOLMSTROM, C., S. JAMES, B. A. NEILAN, D. C. WHITE, and S. KJELLEBERG. "Pseudoalteromonas tunicata sp. nov., a bacterium that produces antifouling agents." International Journal of Systematic Bacteriology 48, no. 4 (October 1, 1998): 1205–12. http://dx.doi.org/10.1099/00207713-48-4-1205.

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Mai-Prochnow, Anne, Jeremy S. Webb, Belinda C. Ferrari, and Staffan Kjelleberg. "Ecological Advantages of Autolysis during the Development and Dispersal of Pseudoalteromonas tunicata Biofilms." Applied and Environmental Microbiology 72, no. 8 (August 2006): 5414–20. http://dx.doi.org/10.1128/aem.00546-06.

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ABSTRACT In the ubiquitous marine bacterium Pseudoalteromonas tunicata, subpopulations of cells are killed by the production of an autocidal protein, AlpP, during biofilm development. Our data demonstrate an involvement of this process in two parameters, dispersal and phenotypic diversification, which are of importance for the ecology of this organism and for its survival within the environment. Cell death in P. tunicata wild-type biofilms led to a major reproducible dispersal event after 192 h of biofilm development. The dispersal was not observed with a ΔAlpP mutant strain. Using flow cytometry and the fluorescent dye DiBAC4(3), we also show that P. tunicata wild-type cells that disperse from biofilms have enhanced metabolic activity compared to those cells that disperse from ΔAlpP mutant biofilms, possibly due to nutrients released from dead cells. Furthermore, we report that there was considerable phenotypic variation among cells dispersing from wild-type biofilms but not from the ΔAlpP mutant. Wild-type cells that dispersed from biofilms showed significantly increased variations in growth, motility, and biofilm formation, which may be important for successful colonization of new surfaces. These findings suggest for the first time that the autocidal events mediated by an antibacterial protein can confer ecological advantages to the species by generating a metabolically active and phenotypically diverse subpopulation of dispersal cells.

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Egan, Suhelen, Sally James, and Staffan Kjelleberg. "Identification and Characterization of a Putative Transcriptional Regulator Controlling the Expression of Fouling Inhibitors in Pseudoalteromonas tunicata." Applied and Environmental Microbiology 68, no. 1 (January 2002): 372–78. http://dx.doi.org/10.1128/aem.68.1.372-378.2002.

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ABSTRACT The dark green pigmented marine bacterium Pseudoalteromonas tunicata colonizes living surfaces and produces a range of extracellular compounds that inhibit common fouling organisms, including marine invertebrate larvae, algae, bacteria, and fungi. We have observed a positive correlation between the antifouling activity of P. tunicata strain D2 and the expression of pigmentation. To address the hypothesis that pigmentation and antifouling may be jointly regulated in this organism and to begin to identify potential regulatory elements, we used transposon mutagenesis to generate a strain of P. tunicata deficient in antifouling activity. The data presented here describe the phenotypic and molecular characterization of a nonpigmented transposon mutant strain of P. tunicata (D2W2). Analyses of the antifouling capabilities of D2W2 demonstrate that this strain is deficient in the ability to inhibit each of the target fouling organisms. Genetic analysis of D2W2 identified a gene, designated wmpR (white mutant phenotype), with high sequence similarity to transcriptional regulators ToxR from Vibrio cholerae and CadC from Escherichia coli. Two-dimensional polyacrylamide gel electrophoresis analysis revealed that WmpR is essential for the expression of a significant subset of stationary-phase-induced proteins likely to be important for the synthesis of fouling inhibitors. The identification of a gene involved in the regulation of expression of antifouling phenotypes will contribute to the understanding of the interactions between bacteria and other surface-colonizing organisms in the marine environment.

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Egan, Suhelen, Sally James, Carola HolmstrÃ¶m, and Staffan Kjelleberg. "Inhibition of algal spore germination by the marine bacterium Pseudoalteromonas tunicata." FEMS Microbiology Ecology 35, no. 1 (March 2001): 67–73. http://dx.doi.org/10.1111/j.1574-6941.2001.tb00789.x.

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Hoke, David E., Suhelen Egan, Paul A. Cullen, and Ben Adler. "LipL32 Is an Extracellular Matrix-Interacting Protein of Leptospira spp. and Pseudoalteromonas tunicata." Infection and Immunity 76, no. 5 (February 19, 2008): 2063–69. http://dx.doi.org/10.1128/iai.01643-07.

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ABSTRACT LipL32 is the major outer membrane protein in pathogenic Leptospira. It is highly conserved throughout pathogenic species and is expressed in vivo during human infection. While these data suggest a role in pathogenesis, a function for LipL32 has not been defined. Outer membrane proteins of gram-negative bacteria are the first line of molecular interaction with the host, and many have been shown to bind host extracellular matrix (ECM). A search for leptospiral ECM-interacting proteins identified the major outer membrane protein, LipL32. To verify this finding, recombinant LipL32 was expressed in Escherichia coli and was found to bind Matrigel ECM and individual components of ECM, including laminin, collagen I, and collagen V. Likewise, an orthologous protein found in the genome of Pseudoalteromonas tunicata strain D2 was expressed and found to be functionally similar and immunologically cross-reactive. Lastly, binding activity was mapped to the C-terminal 72 amino acids. These studies show that LipL32 and an orthologous protein in P. tunicata are immunologically cross-reactive and function as ECM-interacting proteins via a conserved C-terminal region.

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Higgins, Brian P., Adam C. Popkowski, Peter R. Caruana, and Anna C. Karls. "Site-Specific Insertion of IS492 in Pseudoalteromonas atlantica." Journal of Bacteriology 191, no. 20 (August 14, 2009): 6408–14. http://dx.doi.org/10.1128/jb.00771-09.

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ABSTRACT Reversible insertion of IS492 at a site within epsG on the Pseudoalteromonas atlantica chromosome controls peripheral extracellular polysaccharide production and biofilm formation by P. atlantica. High-frequency precise excision of IS492 from epsG requires 5 and 7 bp of flanking DNA, suggesting that IS492 transposition involves a site-specific recombination mechanism. The site specificity of IS492 insertion was examined in P. atlantica and shown to be specific for a 7-bp target, 5′-CTTGTTA-3′. Characterization of numerous insertion events at the target site in epsG indicated that insertion is also orientation specific. The frequency of IS492 insertion at the epsG target site (2.7 × 10−7/cell/generation), determined by quantitative PCR, is 4 to 5 orders of magnitude lower than the frequency of IS492 precise excision from the same site. Comparison of insertion sites for IS492 and the highly related ISPtu2 from Pseudoalteromonas tunicata suggests DNA sequence and/or structural features that may contribute to site recognition and recombination by the transposase of IS492.

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Stelzer, Sacha, Suhelen Egan, Martin R. Larsen, Douglas H. Bartlett, and Staffan Kjelleberg. "Unravelling the role of the ToxR-like transcriptional regulator WmpR in the marine antifouling bacterium Pseudoalteromonas tunicata." Microbiology 152, no. 5 (May 1, 2006): 1385–94. http://dx.doi.org/10.1099/mic.0.28740-0.

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The dark-green-pigmented marine bacterium Pseudoalteromonas tunicata produces several target-specific compounds that act against a range of common fouling organisms, including bacteria, fungi, protozoa, invertebrate larvae and algal spores. The ToxR-like regulator WmpR has previously been shown to regulate expression of bioactive compounds, type IV pili and biofilm formation phenotypes which all appear at the onset of stationary phase. In this study a comparison of survival under starvation or stress between the wild-type P. tunicata strain and a wmpR mutant (D2W2) does not suggest a role for WmpR in regulating starvation- and stress-resistant phenotypes such as those that may be required in stationary phase. Both proteomic [2-dimensional PAGE (2D-PAGE)] and transcriptomic (RNA arbitrarily primed PCR) studies were used to discover members of the WmpR regulon. 2D-PAGE identified 11 proteins that were differentially expressed by WmpR. Peptide sequence data were obtained for six of these proteins and identified using the draft P. tunicata genome as being involved in protein synthesis, amino acid transamination and ubiquinone biosynthesis, as well as hypothetical proteins. The transcriptomic analysis identified three genes significantly up-regulated by WmpR, including a TonB-dependent outer-membrane protein, a non-ribosomal peptide synthetase and a hypothetical protein. Under iron-limitation the wild-type showed greater survival than D2W2, indicating the importance of WmpR under these conditions. Results from these studies show that WmpR controls the expression of genes encoding proteins involved in iron acquisition and uptake, amino acid metabolism and ubiquinone biosynthesis in addition to a number of proteins with as yet unknown functions.

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Hoke, D. E., K. Zhang, S. Egan, and B. Adler. "The Marine Bacterium Pseudoalteromonas Tunicata Alters its Proteome Upon Adhesion to Extracellular Matrix." Journal of Proteomics & Bioinformatics S2, no. 01 (July 2008): 256. http://dx.doi.org/10.4172/jpb.s1000185.

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Bernbom, Nete, Yoke Yin Ng, Staffan Kjelleberg, Tilmann Harder, and Lone Gram. "Marine Bacteria from Danish Coastal Waters Show Antifouling Activity against the Marine Fouling Bacterium Pseudoalteromonas sp. Strain S91 and Zoospores of the Green Alga Ulva australis Independent of Bacteriocidal Activity." Applied and Environmental Microbiology 77, no. 24 (October 14, 2011): 8557–67. http://dx.doi.org/10.1128/aem.06038-11.

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ABSTRACTThe aims of this study were to determine if marine bacteria from Danish coastal waters produce antifouling compounds and if antifouling bacteria could be ascribed to specific niches or seasons. We further assess if antibacterial effect is a good proxy for antifouling activity. We isolated 110 bacteria with anti-Vibrioactivity from different sample types and locations during a 1-year sampling from Danish coastal waters. The strains were identified asPseudoalteromonas,Phaeobacter, andVibrionaceaebased on phenotypic tests and partial 16S rRNA gene sequence similarity. The numbers of bioactive bacteria were significantly higher in warmer than in colder months. While some species were isolated at all sampling locations, others were niche specific. We repeatedly isolatedPhaeobacter gallaeciensisat surfaces from one site andPseudoalteromonas tunicataat two others. Twenty-two strains, representing the major taxonomic groups, different seasons, and isolation strategies, were tested for antiadhesive effect against the marine biofilm-forming bacteriumPseudoalteromonassp. strain S91 and zoospores of the green algaUlva australis. The antiadhesive effects were assessed by quantifying the number of strain S91 orUlvaspores attaching to a preformed biofilm of each of the 22 strains. The strongest antifouling activity was found inPseudoalteromonasstrains. Biofilms ofPseudoalteromonas piscicida,Pseudoalteromonas tunicata, andPseudoalteromonas ulvaepreventedPseudoalteromonasS91 from attaching to steel surfaces.P. piscicidakilled S91 bacteria in the suspension cultures, whereasP. tunicataandP. ulvaedid not; however, they did prevent adhesion by nonbactericidal mechanism(s). SevenPseudoalteromonasspecies, includingP. piscicidaandP. tunicata, reduced the number of settlingUlvazoospores to less than 10% of the number settling on control surfaces. The antifoulingalpPgene was detected only inP. tunicatastrains (with purple and yellow pigmentation), so other compounds/mechanisms must be present in the otherPseudoalteromonasstrains with antifouling activity.

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Franks, A., P. Haywood, C. Holmström, S. Egan, S. Kjelleberg, and N. Kumar. "Isolation and Structure Elucidation of a Novel Yellow Pigment from the Marine Bacterium Pseudoalteromonas tunicata." Molecules 10, no. 10 (October 31, 2005): 1286–91. http://dx.doi.org/10.3390/10101286.

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Mai-Prochnow, Anne, Patricia Lucas-Elio, Suhelen Egan, Torsten Thomas, Jeremy S. Webb, Antonio Sanchez-Amat, and Staffan Kjelleberg. "Hydrogen Peroxide Linked to Lysine Oxidase Activity Facilitates Biofilm Differentiation and Dispersal in Several Gram-Negative Bacteria." Journal of Bacteriology 190, no. 15 (May 23, 2008): 5493–501. http://dx.doi.org/10.1128/jb.00549-08.

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ABSTRACT The marine bacterium Pseudoalteromonas tunicata produces an antibacterial and autolytic protein, AlpP, which causes death of a subpopulation of cells during biofilm formation and mediates differentiation, dispersal, and phenotypic variation among dispersal cells. The AlpP homologue (LodA) in the marine bacterium Marinomonas mediterranea was recently identified as a lysine oxidase which mediates cell death through the production of hydrogen peroxide. Here we show that AlpP in P. tunicata also acts as a lysine oxidase and that the hydrogen peroxide generated is responsible for cell death within microcolonies during biofilm development in both M. mediterranea and P. tunicata. LodA-mediated biofilm cell death is shown to be linked to the generation of phenotypic variation in growth and biofilm formation among M. mediterranea biofilm dispersal cells. Moreover, AlpP homologues also occur in several other gram-negative bacteria from diverse environments. Our results show that subpopulations of cells in microcolonies also die during biofilm formation in two of these organisms, Chromobacterium violaceum and Caulobacter crescentus. In all organisms, hydrogen peroxide was implicated in biofilm cell death, because it could be detected at the same time as the killing occurred, and the addition of catalase significantly reduced biofilm killing. In C. violaceum the AlpP-homologue was clearly linked to biofilm cell death events since an isogenic mutant (CVMUR1) does not undergo biofilm cell death. We propose that biofilm killing through hydrogen peroxide can be linked to AlpP homologue activity and plays an important role in dispersal and colonization across a range of gram-negative bacteria.

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Ballestriero, Francesco, Torsten Thomas, Catherine Burke, Suhelen Egan, and Staffan Kjelleberg. "Identification of Compounds with Bioactivity against the Nematode Caenorhabditis elegans by a Screen Based on the Functional Genomics of the Marine Bacterium Pseudoalteromonas tunicata D2." Applied and Environmental Microbiology 76, no. 17 (July 2, 2010): 5710–17. http://dx.doi.org/10.1128/aem.00695-10.

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ABSTRACT Marine bacteria are a rich, yet underexplored, resource of compounds with inhibitory bioactivity against a range of eukaryotic target organisms. Identification of those inhibitors, however, requires a culturable or genetically tractable producer strain, a prerequisite that is not often fulfilled. This study describes a novel functional genomic screen that is based on expression of inhibitors in a heterogeneous recombinant host (i.e., Escherichia coli). Functional libraries were screened by selective grazing by the nematode Caenorhabditis elegans, in a simple, rapid, high-throughput manner. We applied our approach to discover inhibitors of C. elegans produced by the marine bacterium Pseudoalteromonas tunicata D2, a model organism for exploring a range of antagonistic activities between bacteria and eukaryotes and a known producer of several toxic compounds. Expression of P. tunicata DNA in E. coli and grazing selection by the nematode Caenorhabditis elegans identified two clones, with slow- and fast-killing modes of action. Genomic analysis of the slow-killing clone revealed that the activity was due to a small molecule, tambjamine, while the fast-killing activity involved a gene encoding for a novel protein. Microscopic analysis showed substantial colonization of the intestinal lumen, or rapid death of the nematode without colonization, for the two activities, respectively. The novel functional genomic screen presented here therefore detects new eukaryotic inhibitors with different chemical structures, kinetics, and predicted modes of actions.

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Thomas, Torsten, Flavia F. Evans, David Schleheck, Anne Mai-Prochnow, Catherine Burke, Anahit Penesyan, Doralyn S. Dalisay, et al. "Analysis of the Pseudoalteromonas tunicata Genome Reveals Properties of a Surface-Associated Life Style in the Marine Environment." PLoS ONE 3, no. 9 (September 24, 2008): e3252. http://dx.doi.org/10.1371/journal.pone.0003252.

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García-Fraga, Belén, Abigail F. da Silva, Jacobo López-Seijas, and Carmen Sieiro. "A novel family 19 chitinase from the marine-derived Pseudoalteromonas tunicata CCUG 44952T: Heterologous expression, characterization and antifungal activity." Biochemical Engineering Journal 93 (January 2015): 84–93. http://dx.doi.org/10.1016/j.bej.2014.09.014.

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Faria, Sara I., Rita Teixeira-Santos, Luciana C. Gomes, Elisabete R. Silva, João Morais, Vítor Vasconcelos, and Filipe J. M. Mergulhão. "Experimental Assessment of the Performance of Two Marine Coatings to Curb Biofilm Formation of Microfoulers." Coatings 10, no. 9 (September 18, 2020): 893. http://dx.doi.org/10.3390/coatings10090893.

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Biofilms formed on submerged marine surfaces play a critical role in the fouling process, causing increased fuel consumption, corrosion, and high maintenance costs. Thus, marine biofouling is a major issue and motivates the development of antifouling coatings. In this study, the performance of two commercial marine coatings, a foul-release silicone-based paint (SilRef) and an epoxy resin (EpoRef), was evaluated regarding their abilities to prevent biofilm formation by Cyanobium sp. and Pseudoalteromonas tunicata (common microfoulers). Biofilms were developed under defined hydrodynamic conditions to simulate marine settings, and the number of biofilm cells, wet weight, and thickness were monitored for 7 weeks. The biofilm structure was analyzed by confocal laser scanning microscopy (CLSM) at the end-point. Results demonstrated that EpoRef surfaces were effective in inhibiting biofilm formation at initial stages (until day 28), while SilRef surfaces showed high efficacy in decreasing biofilm formation during maturation (from day 35 onwards). Wet weight and thickness analysis, as well as CLSM data, indicate that SilRef surfaces were less prone to biofilm formation than EpoRef surfaces. Furthermore, the efficacy of SilRef surfaces may be dependent on the fouling microorganism, while the performance of EpoRef was strongly influenced by a combined effect of surface and microorganism.

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Lucas-Elío, Patricia, Daniel Gómez, Francisco Solano, and Antonio Sanchez-Amat. "The Antimicrobial Activity of Marinocine, Synthesized by Marinomonas mediterranea, Is Due to Hydrogen Peroxide Generated by Its Lysine Oxidase Activity." Journal of Bacteriology 188, no. 7 (April 1, 2006): 2493–501. http://dx.doi.org/10.1128/jb.188.7.2493-2501.2006.

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ABSTRACT Marinocine is a broad-spectrum antibacterial protein synthesized by the melanogenic marine bacterium Marinomonas mediterranea. This work describes the basis for the antibacterial activity of marinocine and the identification of the gene coding for this protein. The antibacterial activity is inhibited under anaerobic conditions and by the presence of catalase under aerobic conditions. Marinocine is active only in culture media containing l-lysine. In the presence of this amino acid, marinocine generates hydrogen peroxide, which causes cell death as confirmed by the increased sensitivity to marinocine of Escherichia coli strains mutated in catalase activity. The gene coding for this novel enzyme was cloned using degenerate PCR with primers designed based on conserved regions in the antimicrobial protein AlpP, synthesized by Pseudoalteromonas tunicata, and some hypothetical proteins. The gene coding for marinocine has been named lodA, standing for lysine oxidase, and it seems to form part of an operon with a second gene, lodB, that codes for a putative dehydrogenase flavoprotein. The identity of marinocine as LodA has been demonstrated by N-terminal sequencing of purified marinocine and generation of lodA mutants that lose their antimicrobial activity. This is the first report on a bacterial lysine oxidase activity and the first time that a gene encoding this activity has been cloned.

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Pinkerton, David M, Martin G Banwell, Mary J Garson, Naresh Kumar, Manoel Odorico de Moraes, Bruno C Cavalcanti, Francisco W A. Barros, and Cláudia Pessoa. "Antimicrobial and Cytotoxic Activities of Synthetically Derived Tambjamines C and E - J, BE-18591, and a Related Alkaloid from the Marine Bacterium Pseudoalteromonas tunicata." Chemistry & Biodiversity 7, no. 5 (May 2010): 1311–24. http://dx.doi.org/10.1002/cbdv.201000030.

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Burmï¿½lle, Mette, Jeremy S. Webb, Dhana Rao, Lars H. Hansen, Sï¿½ren J. Sï¿½rensen, and Staffan Kjelleberg. "Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms." Applied and Environmental Microbiology 72, no. 6 (June 2006): 3916–23. http://dx.doi.org/10.1128/aem.03022-05.

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ABSTRACT Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated from the surface of the marine alga Ulva australis, were screened for synergistic interactions within biofilms when present together in different combinations. Four isolates, Microbacterium phyllosphaerae, Shewanella japonica, Dokdonia donghaensis, and Acinetobacter lwoffii, were found to interact synergistically in biofilms formed in 96-well microtiter plates: biofilm biomass was observed to increase by >167% in biofilms formed by the four strains compared to biofilms composed of single strains. When exposed to the antibacterial agent hydrogen peroxide or tetracycline, the relative activity (exposed versus nonexposed biofilms) of the four-species biofilm was markedly higher than that in any of the single-species biofilms. Moreover, in biofilms established on glass surfaces in flow cells and subjected to invasion by the antibacterial protein-producing Pseudoalteromonas tunicata, the four-species biofilms resisted invasion to a greater extent than did the biofilms formed by the single species. Replacement of each strain by its cell-free culture supernatant suggested that synergy was dependent both on species-specific physical interactions between cells and on extracellular secreted factors or less specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms.

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Burke, Catherine, Torsten Thomas, Suhelen Egan, and Staffan Kjelleberg. "The use of functional genomics for the identification of a gene cluster encoding for the biosynthesis of an antifungal tambjamine in the marine bacterium Pseudoalteromonas tunicata." Environmental Microbiology 9, no. 3 (March 2007): 814–18. http://dx.doi.org/10.1111/j.1462-2920.2006.01177.x.

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Skovhus, Torben L., Niels B. Ramsing, Carola Holmström, Staffan Kjelleberg, and Ingela Dahllöf. "Real-Time Quantitative PCR for Assessment of Abundance of Pseudoalteromonas Species in Marine Samples." Applied and Environmental Microbiology 70, no. 4 (April 2004): 2373–82. http://dx.doi.org/10.1128/aem.70.4.2373-2382.2004.

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ABSTRACT A real-time quantitative PCR (RTQ-PCR) method for measuring the abundance of Pseudoalteromonas species in marine samples is presented. PCR primers targeting a Pseudoalteromonas-specific region of the 16S rRNA gene were tested at three different levels using database searches (in silico), a selection of pure cultures (in vitro), and a combined denaturing gradient gel electrophoresis and cloning approach on environmental DNA (in situ). The RTQ-PCR method allowed for the detection of SYBR Green fluorescence from double-stranded DNA over a linear range spanning six orders of magnitude. The detection limit was determined as 1.4 fg of target DNA (1,000 gene copies) measured in the presence of 20 ng of nontarget DNA from salmon testes. In this study, we discuss the importance of robust post-PCR analyses to overcome pitfalls in RTQ-PCR when samples from different complex marine habitats are analyzed and compared on a nonroutine basis. Representatives of the genus Pseudoalteromonas were detected in samples from all investigated habitats, suggesting a widespread distribution of this genus across many marine habitats (e.g., seawater, rocks, macroalgae, and marine animals). Three sample types were analyzed by RTQ-PCR to determine the relative abundance of Pseudoalteromonas ribosomal DNA (rDNA) compared to the total abundance of eubacterial rDNA. The rDNA fractions of Pseudoalteromonas compared to all Eubacteria were 1.55% on the green alga Ulva lactuca, 0.10% on the tunicate Ciona intestinalis, and 0.06% on the green alga Ulvaria fusca.

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Rao, Dhana, Torben Skovhus, Niina Tujula, Carola Holmström, Ingela Dahllöf, Jeremy S. Webb, and Staffan Kjelleberg. "Ability of Pseudoalteromonas tunicata to colonize natural biofilms and its effect on microbial community structure." FEMS Microbiology Ecology, June 23, 2010, no. http://dx.doi.org/10.1111/j.1574-6941.2010.00917.x.

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Gardiner, Melissa, David E. Hoke, and Suhelen Egan. "An ortholog of the Leptospira interrogans lipoprotein LipL32 aids in the colonization of Pseudoalteromonas tunicata to host surfaces." Frontiers in Microbiology 5 (July 3, 2014). http://dx.doi.org/10.3389/fmicb.2014.00323.

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Pinkerton, David M., Martin G. Banwell, and Anthony C. Willis. "ChemInform Abstract: Total Syntheses of Tambjamines C, E, F, G, H, I and J, BE-18591, and a Related Alkaloid from the Marine Bacterium Pseudoalteromonas tunicata." ChemInform 39, no. 17 (April 22, 2008). http://dx.doi.org/10.1002/chin.200817203.

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Journal articles on the topic 'Pseudoalteromonas tunicata'

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