Rubén Araya

Potential probiotic strains in the culture of the Chilean scallop Argopecten purpuratus (Lamarck, 1819)

Abstract This study reports on the search for naturally occurring bacteria which are able to promote the growth and survival of Argopecten purpuratus larvae by inhibiting the activity of other deleterious bacteria that flourish in hatchery cultures. A total of 506 bacterial isolates, obtained from laboratory and hatchery sources, were evaluated for the production of substances inhibitory to a Vibrio anguillarum -related (VAR) larval pathogen, of which 11 (2.2%) were found positive. One of these strains ( Vibrio sp.), when used as a pre-treatment, protected the scallop larvae against subsequent experimental infection with the VAR pathogen.

Selective incorporation of bacteria by Argopecten purpuratus larvae: implications for the use of probiotics in culturing systems of the Chilean scallop.

Abstract Experiments on ingestion rates, colonization and impact of inhibitory producer substances bacteria (IPB) on larvae of Argopecten purpuratus , were carried out to evaluate potential use of bacteria as probiotics in cultures of this Chilean scallop. Three selected strains, named as 11, C33 and 77, obtained from larval cultures of A. purpuratus were tested at different concentrations and incubation times. After 6 h of incubation at a concentration of 10 6 cells ml −1 , A. purpuratus larvae ingested cells of strains 11 and 77, but not those of C33. When comparing bacterial incorporation among these strains, the 77 became the dominant bacteria of the larval microflora, causing no differences in larval survival at different bacterial concentrations. Our results suggest that strain 77 appears as a potential probiotic for scallop larvae and hence, as a promising method to control and prevent infections in hatcheries systems.

Utilización de una biopelícula microalgal multiespecífica para optimizar la fijación larval y el crecimiento de abalón (Haliotis rufescens) en un criadero comercial

This study evaluates the use of a microalgal biofilm composed by a mixture of benthic diatoms such as Amphora cf. capitellata (NV), Nitzschia ovalis arnott (...

Jellyfish Life Stages Shape Associated Microbial Communities, While a Core Microbiome Is Maintained Across All

The key to 650 million years of evolutionary success in jellyfish is adaptability: with alternating benthic and pelagic generations, sexual and asexual reproductive modes, multitudes of body forms and a cosmopolitan distribution, jellyfish are likely to have established a plenitude of microbial associations. Here we explored bacterial assemblages in the scyphozoan jellyfish Chrysaora plocamia (Lesson 1832). Life stages involved in propagation through cyst formation, i.e., the mother polyp, its dormant cysts (podocysts), and polyps recently excysted (excysts) from podocysts – were investigated. Associated bacterial assemblages were assessed using MiSeq Illumina paired-end tag sequencing of the V1V2 region of the 16S rRNA gene. A microbial core-community was identified as present through all investigated life stages, including bacteria with closest relatives known to be key drivers of carbon, nitrogen, phosphorus, and sulfur cycling. Moreover, the fact that half of C. plocamia’s core bacteria were also present in life stages of the jellyfish Aurelia aurita, suggests that this bacterial community might represent an intrinsic characteristic of scyphozoan jellyfish, contributing to their evolutionary success.

The complete genome sequence and analysis of vB_VorS-PVo5, a Vibrio phage infectious to the pathogenic bacterium Vibrio ordalii ATCC-33509

The bacterium Vibrio ordalii is best known as the causative agent of vibriosis outbreaks in fish and thus recognized for generating serious production losses in aquaculture systems. Here we report for the first time on the isolation and the genome sequencing of phage vB_VorS-PVo5, infectious to Vibrio ordalii ATCC 33509. The features as well as the complete genome sequence and annotation of the Vibrio phage are described; vB_VorS-PVo5 consists of a lineal double stranded DNA totaling ~ 80.6 Kb in length. Considering its ability to lyse Vibrio ordalii ATCC 33509, the phage is likely to gain importance in future aquaculture applications by controlling the pathogen and as such replacing antibiotics as the treatment of choice.

Bacterial assemblages associated with coral species of the Mexican Central Pacific

espanolEl papel funcional de las bacterias asociadas a corales y su contribucion a la salud del coral es aun desconocido en gran medida. Es necesario que primero se caracterice el ensamblaje microbiano del coral y sus cambios en la diversidad a traves de las especies de coral, el espacio y tiempo. Los corales ramificados (e.g., genero Pocillopora) son los principales constructores arrecifales a nivel mundial. Este estudio evaluo la estructura bacteriana asociada al mucus y tejidos de Pocillopora damicornis y Pocillopora verrucosa, asi como del agua de mar y sedimentos circundantes en 6 sitios del Pacifico central mexicano. Se emplearon las tecnicas DGGE y RFLP del ADNr 16S para generar los perfiles de bandeo o evaluar la diversidad. Ademas, se evaluo la relacion del ensamblaje bacteriano-coral con variables ambientales y espaciales del entorno arrecifal (de cada sitio), utilizando analisis multivariados. Se obtuvieron 20 Unidades Taxonomicas Operacionales (OTU) diferentes, siendo los sedimentos los que presentaron mayor numero. Se encontro una especificidad de grupos bacterianos para cada especie de coral, asi como entre el tejido y mucus de cada especie. Los resultados mostraron que los grupos de bacterias dominantes variaron entre sustratos y entre sitios, encontrando, solo una variacion espacial significativa. Las variables ambientales que explican la variacion de los grupos bacterianos dominantes en corales y agua de mar fueron las coberturas de macroalgas carnosas, coral vivo y esponja. En cambio, la variacion en los sedimentos fue explicada por las coberturas de arena, escombro y roca. EnglishThe functional role of coral-associated bacteria and their contribution to coral health is still largely unknown. The first necessary step to address this gap in the knowledge is based on characterization of the microbial assemblage of the coral and the species-specific, temporal and spatial variation in its diversity. Branched corals (e.g., genus Pocillopora), are the main builders of coral reefs worldwide. This study evaluated the bacteria associated with the mucus and tissues of Pocillopora damicornis and Pocillopora verrucosa, as well as that of the seawater and surrounding sediments, in 6 sites of the Mexican Central Pacific during summer and winter seasons. The molecular techniques DGGE and RFLP were used with the 16S rDNA to assess the most abundant bacterial OTUs. The relationships between the bacterial-coral assemblage and environmental and spatial variables of the reef surroundings were also evaluated, using the multivariate analyses. Twenty different Operational Taxonomic Units (OTU) were obtained, with the highest number presented by the sediments. Specificity of bacterial groups was found for each coral species, as well as between the tissue and mucus of each species. The results showed that the bacterial dominant groups were similar between seasons, but these showed significant spatial variations among substrates within sites, as well as per substrate across all sites. The environmental variables that explained the variation of the dominant bacterial groups in corals and sea water were the coverages of fleshy macroalgae, live coral and sponge. In contrast, variation in the sediments was explained by the coverages of sand, rubble and rock.

Composición de la comunidad procariota involucrada en la producción de nitrógeno en sedimentos de la bahía Mejillones

Resumen es: La desnitrificacion convencional y la oxidacion anaerobica del amonio (anammox), son procesos que contribuyen a la perdida de N en los sistemas deficient...

Caracterización molecular de las comunidades bacterianas asociadas a sedimentos de un sistema costero del norte de la corriente de Humboldt, bahía de Mejillones del Sur, Chile

To assess the structure of bacterial communities associated to coastal marine sediments of the Humboldt Current System of Mejillones bay (23oS), Chile, we ex...