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Chiaki Kato - One of the best experts on this subject based on the ideXlab platform.
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Draft Genome Sequence of the Deep-Sea Bacterium Moritella sp. JT01 and Identification of Biotechnologically Relevant Genes
Marine Biotechnology, 2017Co-Authors: Robert Cardoso De Freitas, Chiaki Kato, Estácio Jussie Odisi, Marcus Adonai Castro Silva, André Oliveira De Souza LimaAbstract:Deep-sea bacteria can produce various biotechnologically relevant enzymes due to their adaptations to high pressures and low temperatures. To identify such enzymes, we have sequenced the genome of the polycaprolactone-degrading bacterium Moritella sp. JT01, isolated from sediment samples from Japan Trench (6957 m depth), using a Illumina HiSeq2000 sequencer (12.1 million paired-end reads) and CLC Genomics Workbench (version 6.5.1) for the assembly, resulting in a 4.83-Mb genome (42 scaffolds). The genome was annotated using Rapid Annotation using Subsystem Technology (RAST), Protein Homology/analogY Recognition Engine V 2.0 (PHYRE2), and BLAST2Go, revealing 4439 protein coding sequences and 101 RNAs. Gene products with industrial relevance, such as lipases (three) and esterases (four), were identified and are related to bacterium’s ability to degrade polycaprolactone. The annotation revealed proteins related to deep-sea survival, such as cold-shock proteins (six) and desaturases (three). The presence of secondary metabolite biosynthetic gene clusters suggests that this bacterium could produce nonribosomal peptides, polyunsaturated fatty acids, and bacteriocins. To demonstrate the potential of this genome, a lipase was cloned an introduced into Escherichia coli . The lipase was purified and characterized, showing activity over a wide temperature range (over 50% at 20–60 °C) and pH range (over 80% at pH 6.3 to 9). This enzyme has tolerance to the surfactant action of sodium dodecyl sulfate and shows 30% increased activity when subjected to a working pressure of 200 MPa. The genomic characterization of Moritella sp. JT01 reveals traits associated with survival in the deep-sea and their potential uses in biotechnology, as exemplified by the characterized lipase.
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Hydrogen isotope fractionation in lipid biosynthesis by the piezophilic bacterium Moritella japonica DSK1
Chemical Geology, 2014Co-Authors: Jiasong Fang, Chiaki Kato, Li Zhang, Tara C. Davis, Douglas H. BartlettAbstract:Abstract The δD of fatty acids is emerging as an important marine biogeochemical proxy, but the microbiological and environmental factors controlling the variations of δD of the lipids are not fully constrained. We report here the first measurement of D/H ratios of fatty acids in a piezophilic bacterium and show that hydrostatic pressure and the lipid biosynthetic pathway probably exerts dominant control over the δD of fatty acids. Piezophilic bacterium Moritella japonica DSK1 was grown at a pressure of 30 MPa with glucose as substrate. Fatty acids in DSK1 showed vastly varied δD, ranging from + 44.4 to − 171‰. Short-chain fatty acids (SCFA), which are synthesized by the fatty acid synthase (FAS) pathway, had positive δD (average + 3‰), whereas long-chain polyunsaturated fatty acid (LC-PUFA) synthesized via the polyketide pathway exhibited much depleted δD (− 171‰). Our results suggest that the lipid biosynthetic pathways can exert first-order control on the hydrogen isotope signature of bacterial membrane lipids under elevated pressure. Our findings have important implications in marine biogeochemistry. D-depleted fatty acids in marine sediments and in the water column may be derived from piezophilic bacterial reworking and resynthesis of organic matter at high pressure condition. Thus, caution must be exercised in the interpretation of hydrogen isotope signatures of lipids in, e.g., deducing sources of organic matter and tracing microbial biogeochemical processes in the deep ocean and the deep biosphere.
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Isolation and characterization of biodegradable plastic degrading bacteria from deep-sea environments
JAMSTEC Report of Research and Development, 2011Co-Authors: Takayoshi Sekiguchi, Takako Sato, Makiko Enoki, Haruyuki Kanehiro, Katsuyuki Uematsu, Chiaki KatoAbstract:We have isolated thirteen different bacterial strains as poly e-caprolactone (PCL)-degrading bacteria from the Kurile and Japan Trenches at a depth of 5,000-7,000 m (deeper ocean bottoms). The isolates belong to the Shewanella, Moritella, Psychrobacter and Pseudomonas genera. This is the first record of PCL degrading bacteria isolated from deep-sea environments at depth of over 5,000 m. Six strains of the isolates, numbered CT01 in genus Shewanella, CT12, JT01 and JT04 in genus Moritella, JT05 in genus Psychrobacter, and JT08 in genus Pseudomonas were selected for investigation of their cell shapes, degrading abilities for several aliphatic polyesters, and growth profiles. The cell shapes of the strains, except JT05, were rod-shaped, non-spore-forming and motile by means of a single or multi polar flagella. The cell shapes of JT05 were coccal with no visible flagella. From the results of degradation tests on six different alihphatic polyesters, all strains could degrade only PCL. Strains CT01, CT12, JT01 and JT04 are psychrophilic and pressure tolerant bacteria and three strains except JT04 showed typical piezophilic growth profiles. Therefore, it is possible that these strains might play a role in degrading aliphatic polyesters under deep-sea conditions, ie., low-temperatures and high hydrostatic pressures.
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Cloning and characterization of dihydrofolate reductases from deep-sea bacteria.
Journal of biochemistry, 2009Co-Authors: Chiho Murakami, Kaoru Nakasone, Eiji Ohmae, Shin-ichi Tate, Kunihiko Gekko, Chiaki KatoAbstract:Enzymes from organisms living in deep-sea are thought to have characteristic pressure-adaptation mechanisms in structure and function. To better understand these mechanisms in dihydrofolate reductase (DHFR), an essential enzyme in living cells, we cloned, overexpressed and purified four new DHFRs from the deep-sea bacteria Shewanella violacea (svDHFR), Photobacterium profundum (ppDHFR), Moritella yayanosii (myDHFR) and Moritella japonica (mjDHFR), and compared their structure and function with those of Escherichia coli DHFR (ecDHFR). These deep-sea DHFRs showed 33−56% primary structure identity to ecDHFR while far-ultraviolet circular dichroism and fluorescence spectra suggested that their secondary and tertiary structures were not largely different. The optimal temperature and pH for deep-sea DHFRs activity were lower than those of ecDHFR and different from each other. Deep-sea DHFRs kinetic parameters K m and k cat were larger than those of ecDHFR, resulting in 1.5-2.8-fold increase of k cat /K m except for mjDHFR which had a 28-fold decrease. The enzyme activity of ppDHFR and mjDHFR (moderate piezophilic bacteria) as well as ecDHFR decreased as pressure increased, while svDHFR and myDHFR (piezophilic bacteria) showed a significant tolerance to pressure. These results suggest that DHFRs from deep-sea bacteria possess specific enzymatic properties adapted to their life under high pressure.
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Isolation, Cultivation, and Diversity of Deep-Sea Piezophiles
High-Pressure Microbiology, 2008Co-Authors: Chiaki Kato, Yuichi Nogi, Shizuka ArakawaAbstract:This chapter focuses on the isolation, taxonomy, and diversity of piezophilic microorganisms and their habitats. Based upon several studies the authors have indicated that cultivated psychrophilic and piezophilic deep-sea bacteria could be affiliated with one of five genera within the Gammaproteobacteria subgroup: Shewanella, Photobacterium, Colwellia, Moritella, and Psychromonas, which was formally classified as ‘’an unidentified genus’’. The chapter describes taxonomic features of the piezophilic genera. For handling piezophiles for further study, JAMSTEC developed a deep-sea baropiezophile and thermophile isolation and cultivation system, referred to as the DEEPBATH system. The DEEPBATH system consists of four separate devices: (1) a pressure-retaining sampling device, (2) a dilution device under pressure conditions, (3) an isolation device, and (4) a cultivation device. From the analyses of 16S rRNA gene sequences after cultivation at 65 MPa, two groups of the bacterial genera Shewanella and Moritella were identified. The authors have analyzed the microbial community structures by the terminal restriction fragment length polymorphism for the bacterial 16S rRNA gene and determined that the community is drastically changed at different pressure conditions of cultivation using the DEEPBATH system. Piezophiles are characterized by high levels of unsaturated fatty acids in their cell membrane layers, but long-chain polyunsaturated fatty acid (PUFA) like EPA and DHA are not necessarily required for high-pressure growth. The diversity of piezophilic bacteria is closely linked with the global deep-sea ocean circulation, but some of the closed oceans, like the Japan Sea, also contain piezophilic bacteria taxonomically similar to deep-sea microbes in the open oceans.
Yuichi Nogi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature. The production of poly(hydroxyalkanoate)s (PHAs) as ecofriendly bioplastics by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon was examined at atmospheric pressure. Some of the deep-sea bacteria successfully accumulated PHAs that had a wide range of molecular weights and contained 3-hydroxybutyrate, 3-hydroxyvalerate, and the other hydroxyalkanoate units. Furthermore, with a plant oil as its sole source of carbon, Shewanella surugensis produced low-molecular weight oligomeric PHAs. These results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
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Isolation, Cultivation, and Diversity of Deep-Sea Piezophiles
High-Pressure Microbiology, 2008Co-Authors: Chiaki Kato, Yuichi Nogi, Shizuka ArakawaAbstract:This chapter focuses on the isolation, taxonomy, and diversity of piezophilic microorganisms and their habitats. Based upon several studies the authors have indicated that cultivated psychrophilic and piezophilic deep-sea bacteria could be affiliated with one of five genera within the Gammaproteobacteria subgroup: Shewanella, Photobacterium, Colwellia, Moritella, and Psychromonas, which was formally classified as ‘’an unidentified genus’’. The chapter describes taxonomic features of the piezophilic genera. For handling piezophiles for further study, JAMSTEC developed a deep-sea baropiezophile and thermophile isolation and cultivation system, referred to as the DEEPBATH system. The DEEPBATH system consists of four separate devices: (1) a pressure-retaining sampling device, (2) a dilution device under pressure conditions, (3) an isolation device, and (4) a cultivation device. From the analyses of 16S rRNA gene sequences after cultivation at 65 MPa, two groups of the bacterial genera Shewanella and Moritella were identified. The authors have analyzed the microbial community structures by the terminal restriction fragment length polymorphism for the bacterial 16S rRNA gene and determined that the community is drastically changed at different pressure conditions of cultivation using the DEEPBATH system. Piezophiles are characterized by high levels of unsaturated fatty acids in their cell membrane layers, but long-chain polyunsaturated fatty acid (PUFA) like EPA and DHA are not necessarily required for high-pressure growth. The diversity of piezophilic bacteria is closely linked with the global deep-sea ocean circulation, but some of the closed oceans, like the Japan Sea, also contain piezophilic bacteria taxonomically similar to deep-sea microbes in the open oceans.
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Isolation, Cultivation, and Diversity of Deep-Sea Piezophiles
High-Pressure Microbiology, 2008Co-Authors: Chiaki Kato, Yuichi Nogi, Shizuka ArakawaAbstract:This chapter focuses on the isolation, taxonomy, and diversity of piezophilic microorganisms and their habitats. Based upon several studies the authors have indicated that cultivated psychrophilic and piezophilic deep-sea bacteria could be affiliated with one of five genera within the Gammaproteobacteria subgroup: Shewanella, Photobacterium, Colwellia, Moritella, and Psychromonas, which was formally classified as ‘’an unidentified genus’’. The chapter describes taxonomic features of the piezophilic genera. For handling piezophiles for further study, JAMSTEC developed a deep-sea baropiezophile and thermophile isolation and cultivation system, referred to as the DEEPBATH system. The DEEPBATH system consists of four separate devices: (1) a pressure-retaining sampling device, (2) a dilution device under pressure conditions, (3) an isolation device, and (4) a cultivation device. From the analyses of 16S rRNA gene sequences after cultivation at 65 MPa, two groups of the bacterial genera Shewanella and Moritella were identified. The authors have analyzed the microbial community structures by the terminal restriction fragment length polymorphism for the bacterial 16S rRNA gene and determined that the community is drastically changed at different pressure conditions of cultivation using the DEEPBATH system. Piezophiles are characterized by high levels of unsaturated fatty acids in their cell membrane layers, but long-chain polyunsaturated fatty acid (PUFA) like EPA and DHA are not necessarily required for high-pressure growth. The diversity of piezophilic bacteria is closely linked with the global deep-sea ocean circulation, but some of the closed oceans, like the Japan Sea, also contain piezophilic bacteria taxonomically similar to deep-sea microbes in the open oceans.
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Moritella profunda sp. nov. and Moritella abyssi sp. nov., two psychropiezophilic organisms isolated from deep Atlantic sediments.
International journal of systematic and evolutionary microbiology, 2003Co-Authors: Yuichi Nogi, Chiaki Kato, Ziyuan Liang, Hans-jürgen Rüger, Daniel De Kegel, Nicolas GlansdorffAbstract:Strains 2674T (=LMG 21259T =JCM 11435T) and 2693T (=LMG 21258T =JCM 11436T) were isolated from Atlantic sediments at a temperature of 2 degrees C and a depth of 2815 m off the West African coast. Polyphasic evidence indicates that the two strains belong to the genus Moritella and represent distinct species, for which the names Moritella profunda sp. nov. (for strain 2674T) and Moritella abyssi sp. nov. (for strain 2693T) are proposed. The moderate piezophily of the two organisms is intermediate between that of the type species, Moritella marina, which is not piezophilic, and Moritella yayanosii, an obligate piezophile. Both are strict psychrophiles with slightly different cardinal temperatures: at 0.1 MPa, maximal growth rates are observed at 2 degrees C (M. profunda) and 4 degrees C (M. abyssi) with maximum temperatures of 12 degrees C (M. profunda) or 14 degrees C (M. abyssi). The optimal pressure is lower than that at the site of isolation, and raising the temperature to 10 degrees C makes the organisms more piezophilic.
Yoshiharu Doi - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature. The production of poly(hydroxyalkanoate)s (PHAs) as ecofriendly bioplastics by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon was examined at atmospheric pressure. Some of the deep-sea bacteria successfully accumulated PHAs that had a wide range of molecular weights and contained 3-hydroxybutyrate, 3-hydroxyvalerate, and the other hydroxyalkanoate units. Furthermore, with a plant oil as its sole source of carbon, Shewanella surugensis produced low-molecular weight oligomeric PHAs. These results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
Keiji Numata - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature. The production of poly(hydroxyalkanoate)s (PHAs) as ecofriendly bioplastics by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon was examined at atmospheric pressure. Some of the deep-sea bacteria successfully accumulated PHAs that had a wide range of molecular weights and contained 3-hydroxybutyrate, 3-hydroxyvalerate, and the other hydroxyalkanoate units. Furthermore, with a plant oil as its sole source of carbon, Shewanella surugensis produced low-molecular weight oligomeric PHAs. These results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
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Synthesis of poly- and oligo(hydroxyalkanoate)s by deep-sea bacteria, Colwellia spp., Moritella spp., and Shewanella spp
Polymer Journal, 2013Co-Authors: Keiji Numata, Yuichi Nogi, Kumiko Morisaki, Satoshi Tomizawa, Misato Ohtani, Taku Demura, Masayuki Miyazaki, Shigeru Deguchi, Yoshiharu DoiAbstract:This is the first report on synthesis of poly(hydroxyalkanoate)s (PHAs) by various deep-sea bacteria (4 types of Colwellia spp., 11 types of Moritella spp., and 18 types of Shewanella spp.) from glucose, fructose, gluconate, or from one of the several plant oils as the sole source of carbon. The overall results provide important and basic information regarding the production of PHAs by deep-sea bacteria and on the diversity of PHA synthase enzymes in nature.
Bryndis Bjornsdottir - One of the best experts on this subject based on the ideXlab platform.
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Identification of type VI secretion systems in Moritella viscosa.
Veterinary microbiology, 2012Co-Authors: Bryndis Bjornsdottir, Erik Hjerde, Birkir Th Bragason, Thorunn Gudmundsdottir, Nils P Willassen, Bjarnheidur K GudmundsdottirAbstract:The study describes the identification of type VI secretion systems (T6SSs) in Moritella viscosa, the aetiological agent of winter ulcer disease. Despite the availability of commercial vaccines, M. viscosa causes significant financial losses in salmonid farming. The T6SS transports bacterial proteins from the cell into the environment or directly into host cells, and has been implicated with bacterial virulence. The aim of the study was to identify potential T6SSs in M. viscosa and to determine whether it possesses active T6S, providing further insight into the biology of the bacterium. The genome of M. viscosa 06/09/139 was screened for homology with known T6SS encoding genes. Two genetically distinct loci, termed Moritella Type Six Secretion 1 and 2 (mts1 and mts2), were identified as encoding putative T6SSs. Each locus contained known T6S core genes. The mts2 locus contained species specific genes, some of which have not previously been connected with T6S. The mts1 locus showed sequence homology and synteny to T6SSs of the fish pathogen Aliivibrio salmonicida and a non-pathogenic Moritella sp. PE36. The mts2 locus was more similar to a Vibrio parahaemolyticus T6SS. A functional T6SS was confirmed through identification of secreted Mts1-M, a hemolysin coregulated protein (Hcp) which is a part of the secretion system. Both virulent and avirulent M. viscosa isolates expressed two genes encoding Hcp, mts1-M and mts2-M. The results show that M. viscosa has a functional T6S, but the role of the secretion system and possible connections with virulence need further examination.
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Moritella viscosa Virulence. Extracellular Products and Host-Pathogen Interaction
2011Co-Authors: Bryndis BjornsdottirAbstract:Moritella viscosa is the causative agent of winter ulcer disease of marine fish. Knowledge of its pathogenicity is limited and there are no reports comparing the virulence properties of a collection of bacterial isolates. The in vivo and in vitro virulence of the extracellular products (ECP) of 22 M. viscosa isolates was screened. Two non-virulent Canadian isolates and a Norwegian isolate with reduced vir- ulence produced non-lethal ECP. Correlation was obtained between cytotoxin and haemolysin pro- duction of M. viscosa. Isolates from salmon pro- duced ECP with lower cytotoxic and haemolytic activities than ECP of isolates originating from other hosts. Correlation was not found between lethality of ECPs in salmon and cytotoxic or hae- molytic activities. All isolates secreted esterases and a metallopeptidase (MvP1), degraded starch and produced siderophores. Variable levels of ECP protein concentration, different enzymatic activities and siderophore production could not explain dif- ferences in virulence. The results show that virulent M. viscosa isolates secrete a lethal toxic factor of unknown nature and that cytotoxin production may reflect host adaptation. Cell-culture models may not be optimal for determining the virulence of M. viscosa, as no association between cytotoxicity and bacterial virulence was obtained. Non-virulent strains may be useful in future research on M. vis- cosa virulence, as construction of mutants has not been successful.
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Virulence properties of Moritella viscosa extracellular products.
Journal of fish diseases, 2011Co-Authors: Bryndis Bjornsdottir, Thorunn Björg Gudmundsdóttir, B.k. GudmundsdottirAbstract:Moritella viscosa is the causative agent of winter ulcer disease of marine fish. Knowledge of its pathogenicity is limited and there are no reports comparing the virulence properties of a collection of bacterial isolates. The in vivo and in vitro virulence of the extracellular products (ECP) of 22 M. viscosa isolates was screened. Two non-virulent Canadian isolates and a Norwegian isolate with reduced virulence produced non-lethal ECP. Correlation was obtained between cytotoxin and haemolysin production of M. viscosa. Isolates from salmon produced ECP with lower cytotoxic and haemolytic activities than ECP of isolates originating from other hosts. Correlation was not found between lethality of ECPs in salmon and cytotoxic or haemolytic activities. All isolates secreted esterases and a metallopeptidase (MvP1), degraded starch and produced siderophores. Variable levels of ECP protein concentration, different enzymatic activities and siderophore production could not explain differences in virulence. The results show that virulent M. viscosa isolates secrete a lethal toxic factor of unknown nature and that cytotoxin production may reflect host adaptation. Cell-culture models may not be optimal for determining the virulence of M. viscosa, as no association between cytotoxicity and bacterial virulence was obtained. Non-virulent strains may be useful in future research on M. viscosa virulence, as construction of mutants has not been successful.
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Characterisation of an extracellular vibriolysin of the fish pathogen Moritella viscosa.
Veterinary microbiology, 2008Co-Authors: Bryndis Bjornsdottir, Olafur H Fridjonsson, Steinunn Magnusdottir, Valgerdur Andresdottir, Gudmundur O Hreggvidsson, Bjarnheidur K GudmundsdottirAbstract:Moritella viscosa causes winter ulcer disease in salmonids. The aim of the present work was to isolate and partially characterise an extracellular peptidase from M. viscosa, and to study its role in virulence. The peptidase, termed MvP1, was a 38-kDa metallopeptidase produced in late exponential growth. The optimum temperature for MvP1 was 40 degrees C, but the enzyme was active over a broad range of temperatures. MvP1 was non-lethal to salmon at concentrations up to 0.22microg/g fish, but extracellular products were lethal to salmon. MvP1 degraded casein, gelatin and collagen from lumpfish skin. It caused considerable tissue necrosis and hemorrhages at the site of injection, and affected cell-cell adhesions in EPC and BF-2 cell lines, but was not highly cytotoxic. The peptidase partially degraded fish IgM heavy chain but was non-hemolytic. The mvp1 gene was sequenced and encoded a 734-aa polypeptide containing a signal sequence, an N-terminal propeptide, a mature peptidase domain and a C-terminal propeptide. The MvP1 propeptide undergoes both N-terminal and C-terminal processing and different C-terminal processing results in the formation of several active isoforms of the mature peptidase. The catalytic domain showed highest sequence similarity with several vibriolysins (EC 3.4.24.25) originating from Pseudoalteromonas strains, showing up to 80% aa identity. The results indicate that MvP1 is a previously unknown vibriolysin that might affect M. viscosa virulence by aiding in the invasion and dissemination of the bacterium in its host, by causing tissue destruction.
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Characterisation of an extracellular vibriolysin of the fish pathogen Moritella viscosa.
Veterinary Microbiology, 2008Co-Authors: Bryndis Bjornsdottir, Olafur H Fridjonsson, Steinunn Magnusdottir, Valgerdur Andresdottir, Gudmundur O Hreggvidsson, B.k. GudmundsdottirAbstract:Abstract Moritella viscosa causes winter ulcer disease in salmonids. The aim of the present work was to isolate and partially characterise an extracellular peptidase from M. viscosa , and to study its role in virulence. The peptidase, termed MvP1, was a 38-kDa metallopeptidase produced in late exponential growth. The optimum temperature for MvP1 was 40 °C, but the enzyme was active over a broad range of temperatures. MvP1 was non-lethal to salmon at concentrations up to 0.22 μg/g fish, but extracellular products were lethal to salmon. MvP1 degraded casein, gelatin and collagen from lumpfish skin. It caused considerable tissue necrosis and hemorrhages at the site of injection, and affected cell–cell adhesions in EPC and BF-2 cell lines, but was not highly cytotoxic. The peptidase partially degraded fish IgM heavy chain but was non-hemolytic. The mvp1 gene was sequenced and encoded a 734-aa polypeptide containing a signal sequence, an N-terminal propeptide, a mature peptidase domain and a C-terminal propeptide. The MvP1 propeptide undergoes both N-terminal and C-terminal processing and different C-terminal processing results in the formation of several active isoforms of the mature peptidase. The catalytic domain showed highest sequence similarity with several vibriolysins (EC 3.4.24.25) originating from Pseudoalteromonas strains, showing up to 80% aa identity. The results indicate that MvP1 is a previously unknown vibriolysin that might affect M. viscosa virulence by aiding in the invasion and dissemination of the bacterium in its host, by causing tissue destruction.