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Artículo Composición y abundancia de comunidades microbianas asociadas al biofloc en un cultivo de tilapiaMicrobiology community composition and abundance associated to biofloc in tilapia aquaculture Abstract.-The goal of this study was to identify and estimate the abundance of microorganisms associated to biofloc culture system, developed from a 'macrocosm-microcosm' system type. In first section (cylinder 1000 L), 75 juveniles tilapias were inoculated with 5.0 ± 0.95 cm mean length and 4.2 ± 1.08 g mean weight were placed. Daily, the fishes were fed with commercial diet, maintaining a C/N = 15:1 ratio, carbon (molasses and rice dust) and nitrogen (from commercial feed) supply was controlled. This culture condition was maintained during 14 weeks. Several microorganisms associated to the flocs were identified using conventional microbiological tests. To estimate the abundance of organisms associated to flocs, a stereoscopic and optical microscopes were used. Both microscopes were connected to an interphase program for images counting (Image ProPlus v.7.0). The results shown changes in abundance of different microorganisms communities associated to flocs during 14 weeks of experiment. The main groups found in flocs were: bacteria, algae, ciliates, rotifers and nematodes. The results confirm that the bioflocs contributes significantly as in situ natural food source, because a great number of organisms may be associated to them including heterotrophic microbial communities like genus Sphingomonas, Pseudomonas, Bacillus, Nitrospira, Nitrobacter and yeast Rhodotorula sp. The literature show that these microorganisms favoring water quality and physiological good health at organisms in culture. Key words: Bacteria, ciliates, flocs, nematodes, rotifersResumen.-El objetivo de este trabajo fue identificar y estimar la abundancia de microrganismos asociados a un sistema de cultivo biofloc desarrollado a partir de un sistema del tipo 'macrocosmo-microcosmo'. En la primera sección (cilindro de 1000 L), se colocaron 75 tilapias con una longitud aproximada de 5,0 ± 0,95 cm y un peso promedio de 4,2 ± 1,08 g. Los peces fueron alimentados diariamente con una dieta comercial, manteniendo una relación C/N= 15:1, mediante el aporte controlado de carbono (melaza y pulido de arroz) y nitrógeno (proveniente del alimento comercial). Esta condición fue mantenida durante 14 semanas. Se identificaron los diversos microrganismos asociados a los flóculos, utilizando pruebas microbiológicas convencionales. Se determinó la abundancia de los organismos asociados a los flóculos utilizando microscopio óptico y estereoscópico, ambos conectados con el programa de imágenes y de conteo (Image ProPlus v.7.0). Los resultados obtenidos indican cambios en la abundancia de las diversas comunidades de organismos asociados a los flóculos durante las 14 semanas del experimento. Los principales grupos encontrados fueron: bacterias, microalgas, ciliados, rotíferos y nematodos. Los resultados confirman que los flóculos contribuyen como fuente de alimento natur...

The accelerated growth of aquaculture has caused environmental impacts in many countries. Examples include the use of large volumes of water, discharge of effluents with high nutrient content, the occupation of large areas, natural habitat alternation and the escape of exotic species. Biofloc technology (BFT) is an aquaculture tool that requires minimal water exchange, promotes the nutrient recycling optimizing resources and produces natural food in situ by forming suspended microbial aggregates in the water (bioflocs). These microorganisms provide multiple benefits such as water quality control, pathogen resistance and nutritional supplementation. Species such as Litopenaeus vannamei and tilapia have been successfully applied in BFT. In addition, there are also an increasing number of studies focused on alternative species with promising results. This paper describes essential aspects of biofloc technology, its application in aquaculture and the potential to extend its benefits to new aquaculture species such as Chilean river shrimp Cryphiops caementarius. This paper describes the future challenges of this technology as well as opportunities for its application.

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The bee pollen is considered an excellent source of flavonoids, carotenoids, phenolic compounds, sterols and minerals; and possesses the ability to boost the immune system, antioxidant action and other interesting therapeutic effects. This study was carried out aiming to evaluate the inclusion of bee pollen in extruded commercial diets of Nile tilapia fingerlings and its effects on the hepatic‐intestinal histomorphometry and zootechnical performance. A total of 225 tilapia fingerlings (1.25 ± 0.05 g) were distributed in a completely randomized design in 15 tanks (30 L) maintained in a recirculation water system with three treatments (0% or control, 1.5% and 2.5% of bee pollen inclusion) and five replicates. Feeding rates were defined from the weekly biometrics and periodic monitoring of the physical–chemical water quality parameters. The water quality variables remained within the appropriate range for the species throughout the experiment. There was no significant difference for the somatic indexes and zootechnical parameters in this experiment. However, the inclusion of bee pollen in Nile tilapia fingerlings diets showed a linear increase in hepatocyte morphology (p = .0098). For the intestinal variables of villus height a significant linear increase was observed (p < .05) as the pollen inclusion increased. In fish that received 2.5%, the number of goblet cells was significantly higher (p < .001) than control group and 1.5%. In this sense, the inclusion up to 2.5% bee pollen in extruded commercial diets of Nile tilapia fingerlings had a positive impact on hepato‐intestinal histomorphometry without causing negative effects on the zootechnical performance.

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Perfil taxonómico de comunidades bacterianas detectadas con 16S-ARNr en biopelículas marinas autotróficas y heterotróficas utilizadas en la acuaculturaA . Bacterial diversity of phototrophic (PAb) and heterotrophic (Hb) biofilms was studied over time (0, 15 and 30 days of culture)using high throughput sequencing and considering the V3 and V4 hypervariable regions of the 16S rRNA gene. Bacterial composition in terms of relative abundance and diversity showed slight changes during the trial. Proteobacteria was the most abundant phylum in both biofilms during the experimental period. Chlamidiae-Verrucomicrobia, Bacteriodetes, and Planctomycetes were also abundant phyla in the PAb, whereas Planctomycetes, Bacteriodetes, Actinobacteria, and Chlamydiae were the abundant phyla in the Hb. Of the reads assigned up to species level, a total of 27 heterotrophic and autotrophic species were detected in both biofilms, most of them associated with the metabolism of nitrogenous and sulfurous metabolites and organic matter, and the rest with the structural functions in the biofilm. This is the first time some of these species have been reportedly detected in these biofilms or in the marine environment. Results suggest complex interaction networks in microbial conglomerates formed in biofilms, in which bacterial populations seem to play important metabolic and physiological roles. R. Se estudió la diversidad de bacterias de biopelículas fototróficas (PAb) y heterotróficas (Hb) a través del tiempo (0, 15 y 30 días de cultivo) por medio de secuenciación masiva, considerando las regiones hipervariables V3 y V4 del gen 16S ARNr. La composición bacteriana mostró pequeños cambios durante el ensayo en términos de abundancia relativa y diversidad. Proteobacteria fue el filo más abundante en ambas biopelículas durante el experimento. Chlamidiae-Verrucomicrobia, Bacteriodetes y Planctomycetes también fueron filos abundantes en PAb, mientras que Planctomycetes, Bacteriodetes, Actinobacteria y Chlamydiae se registraron en Hb. De las lecturas asignadas a nivel de especie, un total de 27 especies autrotróficas y heterotróficas fueron detectadas en ambas biopelículas, la mayoría de ellas asociadas al metabolismo de compuestos nitrogenados y azufrados y a materia orgánica, y las restantes asociadas a las funciones estructurales en las biopelículas. Esta es la primera vez que se reporta la detección de algunas de estas especies en estas biopelículas e incluso en el ambiente marino. Los resultados sugieren la existencia de complejas redes de interacción en los conglomerados microbianos formados en las bipelículas, en las cuales las poblaciones bacterianas parecen jugar papeles metabólicos y fisiológicos importantes.