Effects of soybean-containing diets on the proximal and distal intestine in Atlantic salmon (Salmo salar): a morphological study

Abstract Background: Intestinal digesta is commonly used for studying responses of microbiota to dietary shifts, yet evidence is accumulating that it represents an incomplete view of the intestinal microbiota. The present work aims to investigate the differences between digesta- and mucosa-associated intestinal microbiota in Atlantic salmon ( Salmo salar ) and how they may respond differently to dietary perturbations. In a 16-week seawater feeding trial, Atlantic salmon were fed either a commercially-relevant reference diet or an insect meal diet containing ~15% black soldier fly ( Hermetia illucens ) larvae meal. The digesta- and mucosa-associated distal intestinal microbiota were profiled by 16S rRNA gene sequencing. Results: Regardless of diet, we observed substantial differences between digesta- and mucosa-associated intestinal microbiota. Microbial richness and diversity were much higher in the digesta than the mucosa. The insect meal diet altered the distal intestinal microbiota resulting in higher microbial richness and diversity. The diet effect, however, depended on the sample origin. Digesta-associated intestinal microbiota showed more pronounced changes than the mucosa-associated microbiota. Multivariate association analyses identified two mucosa-enriched taxa, Brevinema andersonii and unclassified Spirochaetaceae , associated with the expression of genes related to immune responses and barrier function in the distal intestine, respectively. Conclusions: Our data show that salmon intestinal digesta and mucosa harbor microbial communities with clear differences. Mucosa-associated intestinal microbiota seems more resilient to variations in the diet composition than digesta-associated intestinal microbiota. To fully unveil the response of intestinal microbiota to dietary changes, concurrent profiling of digesta- and mucosa-associated intestinal microbiota is recommended whenever feasible.

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Development and regression of soybean meal induced enteritis in Atlantic salmon, Salmo salar L., distal intestine: a comparison with the intestines of fasted fish

Journal of Fish Diseases ◽

10.1111/j.1365-2761.1996.tb00376.x ◽

1996 ◽

Vol 19 (5) ◽

pp. 375-387 ◽

Cited By ~ 364

Author(s):

G Baeverfjord ◽

A Krogdahl

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Soybean Meal ◽

Distal Intestine ◽

Atlantic Salmon Salmo Salar

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Effect of Dietary Carbohydrate-to-Protein Ratio on Gut Microbiota in Atlantic Salmon (Salmo salar)

Animals ◽

10.3390/ani9030089 ◽

2019 ◽

Vol 9 (3) ◽

pp. 89 ◽

Cited By ~ 4

Author(s):

Alejandro Villasante ◽

Carolina Ramírez ◽

Natalia Catalán ◽

Rafael Opazo ◽

Patricio Dantagnan ◽

...

Keyword(s):

Atlantic Salmon ◽

Gut Microbiota ◽

Salmo Salar ◽

High Throughput Sequencing ◽

Wheat Starch ◽

Rrna Gene ◽

Protein Ratio ◽

Distal Intestine ◽

High Carbohydrate ◽

Atlantic Salmon Salmo Salar

Atlantic salmon (Salmo salar) is a carnivorous fish species whose productive performance tends to be suboptimal when fed low-cost carbohydrate rich meals. It is of interest to study the dynamics of gut microbiota communities in salmonids fed high carbohydrate diets since gut microbes are referred to as key players that influence the metabolism and physiology of the host. A study was conducted to determine the effect of feeding a high carbohydrate diet to Atlantic salmon in gut microbiota communities. A medium carbohydrate (15% wheat starch)/medium protein (MC/MP) diet or a high carbohydrate (30% wheat starch)/low protein (HC/LP) diet was fed to triplicate tanks (28 fish each) during four weeks. We conducted an in-depth characterization of the distal intestine digesta microbiota using high-throughput sequencing of the V4 region of the 16S rRNA gene. Firmicutes, Actinobacteria and Proteobacteria were the major phyla determined in either experimental group. Phylum Planctomycetes, class Planctomycetia, order Planctomycetales and genus Lactococcus were significantly more abundant in fish fed the HC/LP diet compared with fish fed the MC/MP diet. Our study suggests feeding a carbohydrate rich meal to salmon exerts a low impact on the structure of gut microbial communities, affecting mostly low-abundance bacteria capable of metabolizing anaerobically carbohydrates as a major energy-yielding substrate.

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Dietary Deoxynivalenol (DON) May Impair the Epithelial Barrier and Modulate the Cytokine Signaling in the Intestine of Atlantic Salmon (Salmo salar)

Toxins ◽

10.3390/toxins10090376 ◽

2018 ◽

Vol 10 (9) ◽

pp. 376 ◽

Cited By ~ 5

Author(s):

Torfinn Moldal ◽

Aksel Bernhoft ◽

Grethe Rosenlund ◽

Magne Kaldhusdal ◽

Erling Koppang

Keyword(s):

Atlantic Salmon ◽

Salmo Salar ◽

Intestinal Barrier ◽

Production Performance ◽

Cytokine Signaling ◽

Control Group ◽

Relative Expression ◽

Distal Intestine ◽

Atlantic Salmon Salmo Salar ◽

Suppressors Of Cytokine Signaling

Impaired growth, immunity, and intestinal barrier in mammals, poultry, and carp have been attributed to the mycotoxin deoxynivalenol (DON). The increased use of plant ingredients in aquaculture feed implies a risk for contamination with mycotoxins. The effects of dietary DON were explored in 12-month-old Atlantic salmon (Salmo salar) (start weight of 58 g) that were offered a standard feed with non-detectable levels of mycotoxins (control group) or 5.5 mg DON/kg feed (DON group). Each group comprised two tanks with 25 fish per tank. Five fish from each tank were sampled eight weeks after the start of the feeding trial, when mean weights for the control and DON groups were 123.2 g and 80.2 g, respectively. The relative expression of markers for three tight junction proteins (claudin 25b, occludin, and tricellulin) were lower, whereas the relative expression of a marker for proliferating cell nuclear antigen was higher in both the mid-intestine and the distal intestine in fish fed DON compared with fish from the control group. The relative expression of markers for two suppressors of cytokine signaling (SOCS1 and SOCS2) were higher in the distal intestine in fish fed DON. There was no indication of inflammation attributed to the feed in any intestinal segments. Our findings suggest that dietary DON impaired the intestinal integrity, while an inflammatory response appeared to be mitigated by suppressors of cytokine signaling. A dysfunctional intestinal barrier may have contributed to the impaired production performance observed in the DON group.

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