in vitro selection of autochthonous lactic acid bacterium from clownfish Amphiprion ocellaris.

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Enterococcus faecium as potential probiotic for ornamental neotropical cichlid fish, Pterophyllum scalare (Schultze, 1823).

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Dietary supplementation of Probiotic Enterococcus faecium improve resistance in Arapaima gigas against Aeromonas hydrophila.

This study evaluated the mortality rate, histopathology and haematological param-eters of Arapaima gigas against Aeromonas hydrophila after 68 days of dietary probiotic supplementation with autochthonous bacterium Enterococcus faecium. Three experi-ments were carried out: the first assay evaluated the lethality of A. hydrophila, the second and the third assay evaluated the fish supplemented subjected to A. hydrophilalethal dose 30% (106 CFU ml−1) and lethal dose 100% (108CFU ml−1) respectively. The clinical signs, blood changes, histopathological alterations and mortalities were evalu-ated. At the first experiment, the concentrations of 106 and 108CFU.mL−1 with A. hy-drophila caused 33% and 100% of mortality. The A. hydrophila infection provoked clinical signs such as dark skin, ulceration, haemorrhage, pale gills and liver, hepatic alterations, hyperaemia, hepatic cord breakdown, cellular deforming, lipid degener-ation and necrosis. In the second experiment, no mortality occurred onto fish fed with probiotic. Furthermore, in the third experiment, fish submitted to probiotic sup-plementation showed reduction in mortality of 75% compared with the control and fish fed with probiotic diets at 108CFU g−1 not presented any clinical signs. For these reasons, Arapaima gigas juveniles previously submitted to probiotic supplementation with E. faecium (108CFU g−1) shows better physiological and immunological response, improving resistance against A. hydrophila infection

Comparative effects of autochthonous single-strain and multistrain probiotics on the productive performance and disease resistance in Colossoma macropomum (Cuvier, 1818).

This study evaluated the effects of autochthonous single-strain and multi-strain (mix) probiotics on the zootechnical performance and sanitary conditions of juvenile neotropical fish. Fingerlings of tambaqui (Colossoma macropomum) were fed three diets of single-strain probiotics (two Enterococcus faecium strains and one Bacillus cereus autochthonous strain) and a multi-strain probiotic diet (a mix of three probiotic strains) for 120&#8201;days. After dietary supplementation, 90 tambaquis were intraperitoneally injected with Aeromonas hydrophila at a concentration of 1.8&#8201;×&#8201;108 &#8201;CFU·g&#8722;1. Clinical signs of disease, infectious intensity and accumulated mortality rates were evaluated. The use of diets containing probiotics, regardless of strain, enhanced productive performance from 90 experimental days (p<&#8201;0.05). The multi-strain probiotics reduced the presence of potentially pathogenic bacteria in the intestine. Fish fed probiotics showed improved resistance to A. hydrophila infection, while the diets containing B. cereus (an autochthonous probiotic) and multi-strain probiotic promoted the lowest mortality rates and higher leucocyte and thrombocyte counts (p<&#8201;0.05). The results revealed that the use of probiotics as a single autochthonous or multi-strain probiotic enhanced fish growth, prevented dysbiosis and increased disease resistance

Comparative effects of using a single strain probiotic and multi-strain probiotic on the productive performance and disease resistance in Oreochromis niloticus.

The study was carried out to evaluate the effect of dietary supplementation of three probiotic strains in isolation and a multi-strain formulation (mix) on the rearing of tilapia, based on the parameters of productive performance and resistance to infection. A total of 240 juveniles of Oreochromis niloticus (6.71 ± 0.93 g and 61.88 ± 1.44 mm) were fed for 90 days with fish food containing two varieties of Enterococcus faecium and one variety of Bacillus cereus following therapeutic concentrations reported in the literature, and one multi-strain formulation containing the three organisms. After the period of food supplementation, 45 specimens were injected intraperi-toneally with 300 &#956;L of Streptococcus agalactiae at a lethal concentration of 1.7 × 107 CFU.g

Seleção de bactéria espécie-específica com potencial probiótico para o tambaqui.

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Is There a Seamount Effect on Microbial Community Structure and Biomass? The Case Study of Seine and Sedlo Seamounts (Northeast Atlantic)

Seamounts are considered to be “hotspots” of marine life but, their role in oceans primary productivity is still under discussion. We have studied the microbial community structure and biomass of the epipelagic zone (0–150 m) at two northeast Atlantic seamounts (Seine and Sedlo) and compared those with the surrounding ocean. Results from two cruises to Sedlo and three to Seine are presented. Main results show large temporal and spatial microbial community variability on both seamounts. Both Seine and Sedlo heterotrophic community (abundance and biomass) dominate during winter and summer months, representing 75% (Sedlo, July) to 86% (Seine, November) of the total plankton biomass. In Seine, during springtime the contribution to total plankton biomass is similar (47% autotrophic and 53% heterotrophic). Both seamounts present an autotrophic community structure dominated by small cells (nano and picophytoplankton). It is also during spring that a relatively important contribution (26%) of large cells to total autotrophic biomass is found. In some cases, a “seamount effect” is observed on Seine and Sedlo microbial community structure and biomass. In Seine this is only observed during spring through enhancement of large autotrophic cells at the summit and seamount stations. In Sedlo, and despite the observed low biomasses, some clear peaks of picoplankton at the summit or at stations within the seamount area are also observed during summer. Our results suggest that the dominance of heterotrophs is presumably related to the trapping effect of organic matter by seamounts. Nevertheless, the complex circulation around both seamounts with the presence of different sources of mesoscale variability (e.g. presence of meddies, intrusion of African upwelling water) may have contributed to the different patterns of distribution, abundances and also changes observed in the microbial community

Host-Adaptation of Francisella tularensis Alters the Bacterium's Surface-Carbohydrates to Hinder Effectors of Innate and Adaptive Immunity

The gram-negative bacterium Francisella tularensis survives in arthropods, fresh water amoeba, and mammals with both intracellular and extracellular phases and could reasonably be expected to express distinct phenotypes in these environments. The presence of a capsule on this bacterium has been controversial with some groups finding such a structure while other groups report that no capsule could be identified. Previously we reported in vitro culture conditions for this bacterium which, in contrast to typical methods, yielded a bacterial phenotype that mimics that of the bacterium's mammalian, extracellular phase.SDS-PAGE and carbohydrate analysis of differentially-cultivated F. tularensis LVS revealed that bacteria displaying the host-adapted phenotype produce both longer polymers of LPS O-antigen (OAg) and additional HMW carbohydrates/glycoproteins that are reduced/absent in non-host-adapted bacteria. Analysis of wildtype and OAg-mutant bacteria indicated that the induced changes in surface carbohydrates involved both OAg and non-OAg species. To assess the impact of these HMW carbohydrates on the access of outer membrane constituents to antibody we used differentially-cultivated bacteria in vitro to immunoprecipitate antibodies directed against outer membrane moieties. We observed that the surface-carbohydrates induced during host-adaptation shield many outer membrane antigens from binding by antibody. Similar assays with normal mouse serum indicate that the induced HMW carbohydrates also impede complement deposition. Using an in vitro macrophage infection assay, we find that the bacterial HMW carbohydrate impedes TLR2-dependent, pro-inflammatory cytokine production by macrophages. Lastly we show that upon host-adaptation, the human-virulent strain, F. tularensis SchuS4 also induces capsule production with the effect of reducing macrophage-activation and accelerating tularemia pathogenesis in mice.F. tularensis undergoes host-adaptation which includes production of multiple capsular materials. These capsules impede recognition of bacterial outer membrane constituents by antibody, complement, and Toll-Like Receptor 2. These changes in the host-pathogen interface have profound implications for pathogenesis and vaccine development