Evaluation of selected probiotics and bovine lactoferrin as feed supplements for rainbow trout (Oncorhynchus mykiss Walbaum) for applications in aquaculture

A series of investigations were carried out to assessth e intestinal microbiota of rainbow trout and the potential applications of probiotics and bovine lactoferrin (M). Farm and aquarium reared rainbow trout were examined with specific emphasis on the autochthonous microbial communities. Culture-based, culture-independent and electron microscopical investigations revealed mixed, complex microbial communities in all intestinal regions. DGGE based analysis revealed unique species present either only as allochthonous populations or autochthonous populations. 16S rRNA sequence analysis allowed species level identification of a range of isolates, many of which have not been identified from the rainbow trout digestive tract previously. Two ftirther investigations were carried out to assess the potential of using commercial probiotics and bovine Lf on growth, feed utilisation, health and intestinal colonisation of rainbow trout. Standard commercial diets were supplemented with B. subtills, B. licheniformis and Enterococcus faecium either singularly or synergistically. When comparing the findings of the joint study it can be concluded that the application of probiotics with rainbow trout, and likely other finfish species, is highly complicated. Full intestinal replacement of indigenous microbiota is not likely to be a good idea when using E. faecium; the results indicate that a synergistic relationship with the indigenous microbiota is likely to be involved in providing host benefits. Bacillus probiotics only appeared to be effective at high intestinal levels indicating that a synergistic relationship with the indigenous microbiota may not be as important. T'he joint study also indicates that it is not always possible to reproduce probiotic benefits even when using the same probionts, the same fish species and similar rearing conditions. Thus, the physiological status of the fish and the indigenous microbiota are likely to play an important role in the outcome of probiotic administration. A subsequent trial was conducted to evaluate Pediococcus acidilactic! as a probiotic for rainbow trout. The experiment was conducted to supplement the diet with either vegetative cells or lyophilised powder (as commercially provided). Despite successful intestinal colonisation, irrelevant of supplementation form few significant benefits were observed. SEM of the posterior mucosa revealed a localised colonisation pattern of P. acidilactic! between the mucosal folds similar to the observed indigenous microbiota from the farmed fish. This revelation led to a further trial to investigate the nature of probiotic colonisation through the gastro-intestinal tract using electron microscopy. The study confirmed the high colonisation of P. acidilactici on the epithelium of the anterior intestine and posterior intestine. However, it was not possible to observe such colonisation with Bacillus spp. or E. faeclum; despite culture-based results to the contrary. It is likely that the true mucosal colonisation may sometimes be confused with colonisation of the mucus layer as opposed to actual attachment to the epithelium itself. Therefore, it is crucial to utilise electron microscopy in order to confirm epithelial colonisation. The nature of both the indigenous microbiota and the application of probiotics appears to be more complicated than previously thought and continued research is clearly warranted

Phaeobacter gallaeciensis Reduces Vibrio anguillarum in Cultures of Microalgae and Rotifers, and Prevents Vibriosis in Cod Larvae

Phaeobacter gallaeciensis can antagonize fish-pathogenic bacteria in vitro, and the purpose of this study was to evaluate the organism as a probiont for marine fish larvae and their feed cultures. An in vivo mechanism of action of the antagonistic probiotic bacterium is suggested using a non-antagonistic mutant. P. gallaeciensis was readily established in axenic cultures of the two microalgae Tetraselmis suecica and Nannochloropsis oculata, and of the rotifer Brachionus plicatilis. P. gallaeciensis reached densities of 107 cfu/ml and did not adversely affect growth of algae or rotifers. Vibrio anguillarum was significantly reduced by wild-type P. gallaeciensis, when introduced into these cultures. A P. gallaeciensis mutant that did not produce the antibacterial compound tropodithietic acid (TDA) did not reduce V. anguillarum numbers, suggesting that production of the antibacterial compound is important for the antagonistic properties of P. gallaeciensis. The ability of P. gallaeciensis to protect fish larvae from vibriosis was determined in a bath challenge experiment using a multidish system with 1 larva per well. Unchallenged larvae reached 40% accumulated mortality which increased to 100% when infected with V. anguillarum. P. gallaeciensis reduced the mortality of challenged cod larvae (Gadus morhua) to 10%, significantly below the levels of both the challenged and the unchallenged larvae. The TDA mutant reduced mortality of the cod larvae in some of the replicates, although to a much lesser extent than the wild type. It is concluded that P. gallaeciensis is a promising probiont in marine larviculture and that TDA production likely contributes to its probiotic effect

European Sea Bass (Dicentrarchus labrax) immune status and disease resistance are impaired by arginine dietary supplementation

Infectious diseases and fish feeds management are probably the major expenses in the aquaculture business. Hence, it is a priority to define sustainable strategies which simultaneously avoid therapeutic procedures and reinforce fish immunity. Currently, one preferred approach is the use of immunostimulants which can be supplemented to the fish diets. Arginine is a versatile amino acid with important mechanisms closely related to the immune response. Aiming at finding out how arginine affects the innate immune status or improve disease resistance of European seabass (Dicentrarchus labrax) against vibriosis, fish were fed two arginine-supplemented diets (1% and 2% arginine supplementation). A third diet meeting arginine requirement level for seabass served as control diet. Following 15 or 29 days of feeding, fish were sampled for blood, spleen and gut to assess cell-mediated immune parameters and immune-related gene expression. At the same time, fish from each dietary group were challenged against Vibrio anguillarum and survival was monitored. Cell-mediated immune parameters such as the extracellular superoxide and nitric oxide decreased in fish fed arginine-supplemented diets. Interleukins and immune-cell marker transcripts were down-regulated by the highest supplementation level. Disease resistance data were in accordance with a generally depressed immune status, with increased susceptibility to vibriosis in fish fed arginine supplemented diets. Altogether, these results suggest a general inhibitory effect of arginine on the immune defences and disease resistance of European seabass. Still, further research will certainly clarify arginine immunomodulation pathways thereby allowing the validation of its potential as a prophylactic strategy.European Union's Seventh Framework Programme AQUAEXCEL (Aquaculture Infrastructures for Excellence in European Fish Research) [262336]; AQUAIMPROV [NORTE-07-0124-FEDER-000038]; North Portugal Regional Operational Programme (ON. 2 - O Novo Norte) , under the National Strategic Reference Framework, through the European Regional Development Fund; North Portugal Regional Operational Programme (ON. 2 - O Novo Norte), under the National Strategic Reference Framework through the COMPETE - Operational Competitiveness Programme; Fundacao para a Ciencia e Tecnologia; Fundacao para a Ciencia e Tecnologia [SFRH/BD/89457/2012, SFRH/BPD/77210/2011]; Generalitat Valenciana through the project REVIDPAQUA [ISIC/2012/003]; [PEst-C/MAR/LA0015/2013]; [UID/Multi/04423/2013]info:eu-repo/semantics/publishedVersio

Black soldier fly, Hermetia illucens, larvae meal improves intestinal health and growth performance of Nile tilapia, Oreochromis niloticus, juveniles

This study investigated the effects of dietary black soldier fly (BSF) larvae, Hermetia illucens, meal on growth performance, feed utilization, intestinal health, and immune response in Nile tilapia, Oreochromis niloticus, juveniles. The fish (initial weight: 7.28 ± 0.09 g) were reared in a recirculatory aquaculture system (RAS) and fed diets containing different levels of defatted BSF larvae meal: 0% (control diet), 20% (BSF20), and 40% (BSF40). At the end of the feeding trial, the final body weight, weight gain, specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) were significantly (p \u3c 0.05) improved with increasing BSF meal inclusion levels in the diet. Histological analysis of the intestine revealed that mucosal fold length (MFL), muscularis thickness (MT), and goblet cell density (GCD) were significantly elevated by the BSF meal compared with the control. In addition, intraepithelial lymphocytes (IELs) and the enterocyte microvilli length were significantly elevated in BSF40-fed fish compared with the control. Gene expression analysis showed that intestinal chitin digestion-related (endochitinase A) and amino acid transporter (Slc6a18) genes were not significantly affected by the BSF meal. However, the expression of peptide transporter Slc15a1a was upregulated in the fish fed BSF40 compared to the control. Moreover, posterior intestine and head kidney cytokine (IL-1β, TNF-α, and IL-10) gene expression levels were not significantly affected by the inclusion of the BSF meal. Therefore, these results suggest that the BSF meal up to a 40% inclusion level can be used as an alternative protein source in the diets of Nile tilapia juveniles to promote growth and intestinal health

Evaluation of Prebiotic and Probiotic Effects on the Intestinal Gut Microbiota and Histology of Atlantic salmon (Salmo salar L.)

In the present study the impact on gut microbiology and indigenous gut histology of Atlantic salmon (Salmo salar L.) was investigated following feeding of a control and a prebiotic (EWOS prebiosal®) diet and ex vivo exposure to saline or the probiotic bacterium Carnobacterium divergens. The results showed that ex vivo exposure of C. divergens at 108 CFU ml-¹ did not cause cell damage to the intestine tract of Atlantic salmon. Furthermore, prior provision of dietary prebiotic elevated the ability of C. divergens to adhere to the epithelium or mucus layer in the proximal intestine, where culturable heterotrophic bacterial levels (which were identified as C. divergens) were elevated by 234% compared to the control. This effect was not apparent in the distal intestine. The ability of isolated carnobacteria from the ex vivo experiment to inhibit growth of two fish pathogenic bacteria (Yersinia rückeri and Aeromonas salmonicida ssp. salmonicida) was assessed. Extracellular products from all 11 of the isolated carnobacteria strains, plus the type strain Carnobacterium inhibens CCUG 31728, inhibited the in vitro growth of Y. rückeri. However, only extracellular products from C. divergens isolate 57 inhibited the growth of A. salmonicidapublishedVersio

Autolyzed brewer\u27s yeast enhances growth and intestinal health in early life stages of Nile tilapia (Oreochromis niloticus L.)

The early life stages of fish are critical for determining the overall productivity and sustainability of aquaculture operations. This study investigated the effects of dietary autolyzed brewer\u27s yeast (ABY) on the growth performance and intestinal health of Nile tilapia fry (Oreochromis niloticus). A 35-day feeding trial with 480 Nile tilapia fry across 12 experimental tanks tested the effects of diets supplemented with 1, 2, and 4 g/kg of ABY, with a control diet for comparison. The results indicated that the diet which had 1 g/kg ABY supplementation (ABY1) significantly enhanced the weight gain and specific growth rate (SGR) while reducing feed conversion ratio (FCR) compared to the control diet. Intestinal gene expression analysis showed significant upregulation of immunoregulatory genes (tlr2, il10, il1β, and igm), and a tight junction gene (occludin) in the ABY1 group. Conversely, tnfα expression was significantly downregulated in the ABY1 and ABY2 groups, indicating a potential anti-inflammatory effect. Histological analysis of the mid-intestine revealed healthy morphology with no significant differences in mucosal fold length, muscularis thickness, lamina propria width, and goblet cell count among the treatment groups. The findings demonstrate that supplementing diets with ABY at 1 g/kg level enhances growth performance and modulates the intestinal immune response of Nile tilapia fry, without compromising intestinal integrity. This study offers valuable insights into using ABY as a functional feed additive to enhance Nile tilapia health and development, as well as to promote aquaculture sustainability

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes