Examinando por Autor "Poblete-Morales, M."

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    Arthrobacter ulcerisalmonis sp. Nov., isolated from an ulcer of a farmed atlantic salmon (salmo salar), and emended description of the genus arthrobacter sensu lato
    (Microbiology Society, 2020) Kämpfer, P.; Busse, H.; Schumann, P.; Criscuolo, A.; Clermont, D.; Irgang, R.; Poblete-Morales, M.; Glaeser, S.; Avendaño-Herrera, R.
    A Gram-stain positive, pleomorphic, oxidase-negative, non-motile isolate from the ulcer of a farmed Atlantic salmon (Salmo salar), designated strain T11bT, was subjected to a comprehensive taxonomic investigation. A comparative analysis of the 16S rRNA gene sequence showed highest similarities to the type strains of Pseudarthrobacter siccitolerans (98.1%) and Arthro-bacter methylotrophus and Pseudarthrobacter phenanthrenivorans (both 98.0 %). The highest ANI value observed between the assembled genome of T11bT and the publicly available Pseudarthrobacter and Arthrobacter type strain genomes were 81.15 and 80.99 %, respectively. The major respiratory quinone was menaquinone MK-9(H2). The polyamine pattern contained pre-dominantly spermidine. The polar lipid profile consisted of the major lipids diphosphatidylglycerol, phosphatidylglycerol, monogalactosyl-diacylglycerol and dimannosylglyceride. Minor amouts of trimannosyldiacylglycerol and phosphatidylinositol were also detected. The peptidoglycan was of the type A3α l-Lys–l-Ser–l-Thr–l-Ala (A11.23). In the fatty acid profile, anteiso and iso branched fatty acids predominated (anteiso C15: 0, iso C16: 0, anteiso C17: 0). Moderate to low DNA–DNA similarities, physiological traits as well as unique traits in the fatty acid pattern distinguished strain T11bT from the next related species. All these data point to the fact that strain T11bT represents a novel species of the genus Arthrobacter for which we propose the name Arthrobacter ulcerisalmonis sp. nov. The type strain is T11bT (=CIP 111621T=CCM 8854T=LMG 30632T=DSM 107127T).
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    Biochemical, serological, and genetic characterisation of Renibacterium salmoninarum isolates recovered from salmonids in Chile
    (FRS Marine Laboratory, 2017) Bethke, J.; Quezada, J.; Poblete-Morales, M.; Irgang, R.; Yáňez, A.
    The Gram-positive Renibacterium salmoninarum causes bacterial kidney disease, a serious threat to Chilean salmon farming. To aid in vaccine development, this study used biochemical, antigenic, and genetic techniques to characterise 39 R. salmoninarum isolates from diseased Salmo salar and Oncorhynchus kisutch. Regardless of host, R. salmoninarum isolates were highly homogeneous pheno-typically. However, the isolates presented varied hydrophobicity (10-90%), as found by hydrocarbon adhesions, and distinct siderophores production, as evaluated on chrome azurol S agar. Serological assays established antigenic homogeneity among isolates, which can facilitate vaccine development. While western-blot profiles (using antiserum against iron-limited R. salmoninarum) differed, all isolates belonged to the same serogroup. Finally, RAPD, ERIC-PCR, and REP-PCR supported genetic R. salmoninarum homogeneity, suggesting clonal relationships. In conclusion, high homogeneity might facilitate vaccine development, but in vivo studies are needed to clarify the relationship of R. salmoninarum virulence with hydrophobicity/siderophores synthesis.
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    Isolation, characterization and virulence potential of tenacibaculum dicentrarchi in salmonid cultures in Chile
    (Blackwell Publishing Ltd, 2016-04) Avendaño-Herrera, R.; Irgang, R.; Sandoval, C.; Moreno-Lira, P.; Houel, A.; Duchaud, E.; Poblete-Morales, M.; Nicolas, P.; Ilardi, P.
    In this study, we isolated, identified and characterized isolates of Tenacibaculum dicentrarchi in Atlantic salmon (Salmo salar) farmed in Chile for the first time. In 2010 and 2014, mortalities were observed in Atlantic salmon (average weight 25–30 and 480–520 g, respectively) at an aquaculture centre in Puerto Montt, Chile. Severe tail rots, frayed fins and, in some cases, damaged gills were detected. Wet smear analyses of these lesions revealed a high occurrence of Gram-negative, filamentous bacteria. Microbiological analysis of infected gill and tail tissues yielded six bacterial isolates. All were identified as T. dicentrarchi through polyphasic taxonomy, which included phenotypic characterization, 16S rRNA sequencing and multilocus sequence typing. The latter method revealed a close relationship of the Chilean genotype with the T. dicentrarchi type strain and two Norwegian Atlantic cod (Gadus morhua) isolates. The pathogenic potential of the TdChD05 isolate was assessed by challenging Atlantic salmon and rainbow trout (Oncorhynchus mykiss) for one hour, which resulted in mean cumulative mortal ity rates of 65% and 93%, respectively, as well as clinical signs 14 days post-chal lenge. However, challenged Coho salmon (Oncorhynchus kisutch) presented no mortalities or clinical signs of infection. These findings indicate that the geo graphical and host distribution of T. dicentrarchi is wider than previously estab lished and that this bacterium may have negative impacts on salmonid cultures.
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    Psychrobacter pygoscelis sp. Nov. isolated from the penguin pygoscelis papua
    (Microbiology Society, 2020) Kämpfer, P.; Glaeser, S.; Irgang, R.; Fernández-Negrete, G.; Poblete-Morales, M.; Fuentes-Messina, D.; Martín, M.; Avendaño-Herrera, R.
    One slightly beige-white pigmented, Gram-stain-negative, rod-shaped bacterium, strain I-STPP5bT, was isolated from the trachea of a Gentoo penguin chick individual (Pygoscelin papua) investigated in Fildes Bay, Chilean Antarctic (62° 12′ S, 58° 57′ W). I-STPP5bT consists of a 3.4 Mb chromosome with a DNA G+C content of 44.4 mol%. Of the 3056 predicted genes, 1206 were annotated as hypothetical proteins and 51 were tRNAs. Phylogenetic analysis based on nearly full-length 16S rRNA gene sequences showed that the isolate shared a 16S rRNA gene sequence identity to the type strains of Psychrobacter phenylpyruvicus (98.8%), Psychrobacter arenosus and Psychrobacter pasteurii (both 98.3%), Psychrobacter piechaudii (98.2%) and Psychrobacter sanguinis (98.1%), but 16S rRNA gene sequence similarities to all other Psychrobacter species were ≤98.0%. Partial gyrB nucleotide and amino acid sequence similarities among strain STPP5bT and the next related type strains were all below 81.8 and 92.9%, respectively. DNA–DNA hybridisation (DDH) with P. phenylpyruvicus LMG 5372T, P. arenosus DSM 15389T and P. sanguinis DSM 23635T also showed low values (all below 30%). The main cellular fatty acids of the strain were C18:1 ω9c and C16:1 ω7c and/or C16:1 ω6c. Based on phylogenetic, chemotaxonomic, genomic and phenotypic analyses we propose a new species of the genus Psychrobacter, with the name Psychrobacter pygoscelis sp. nov. and strain I-STPP5bT (=CIP 111410T= CCM 8799T=LMG 30301T) as type strain.