Abstract
Prebiotics are substrates intended to sculpt gut microbial communities as they are selectively utilized by the microorganisms to exert beneficial health effects on hosts. Macroalga-derived oligosaccharides are candidate prebiotics, and herein, we determined the effects of Laminaria sp.-derived alginate oligosaccharide (AlgOS) on the distal intestinal microbiota of Atlantic salmon (Salmo salar). Using a high-throughput 16S rRNA gene amplicon sequencing technique, we investigated the microbiota harbored in the intestinal content and mucus of the fish offered feeds supplemented with 0.5 and 2.5% AlgOS. We found that the prebiotic shifts the intestinal microbiota profile; alpha diversity was significantly reduced with 2.5% AlgOS while with 0.5% AlgOS the alteration occurred without impacting the bacterial diversity. Beta diversity analysis indicated the significant differences between control and prebiotic-fed groups. The low supplementation level of AlgOS facilitated the dominance of Proteobacteria (including Photobacterium phosphoreum, Aquabacterium parvum, Achromobacter insolitus), and Spirochaetes (Brevinema andersonii) in the content or mucus of the fish, and few of these bacteria (Aliivibrio logei, A. parvum, B. andersonii, A. insolitus) have genes associated with butyrate production. The results indicate that the low inclusion of AlgOS can plausibly induce a prebiotic effect on the distal intestinal microbiota of Atlantic salmon. These findings can generate further interest in the potential of macroalgae-derived oligosaccharides for food and feed applications.
Highlights
Prebiotics, recently defined by Gibson et al (2017) are “substrates that are selectively utilized by the host microorganisms conferring a health benefit.” They are intended to evoke beneficial effects on the host through microbial manipulation and the entailing microbial metabolite production
To understand the effects of alginate oligosaccharide (AlgOS) on the bacterial diversity and composition of the distal intestinal (DI) content and mucus, we describe the alterations in the AlgOS-fed fish compared to the control fish
Culture-dependent studies are required to ascertain the ability of the above-mentioned high abundant bacteria in AlgOS-L group in stimulating the production of butyrate in Atlantic salmon. This comprehensive characterization has revealed the effects of dietary supplementation of the Laminaria sp.-derived AlgOS on the intestinal bacterial communities of Atlantic salmon
Summary
Prebiotics, recently defined by Gibson et al (2017) are “substrates that are selectively utilized by the host microorganisms conferring a health benefit.” They are intended to evoke beneficial effects on the host through microbial manipulation and the entailing microbial metabolite production. Prebiotics, recently defined by Gibson et al (2017) are “substrates that are selectively utilized by the host microorganisms conferring a health benefit.” They are intended to evoke beneficial effects on the host through microbial manipulation and the entailing microbial metabolite production. Studies that employed molecular-based methods have provided evidence on the selective effect of prebiotics; they affect certain (e.g., Bifidobacterium, Anaerostipes, and Bilophila) but not all microorganisms (Vandeputte et al, 2017). Prebiotics such as the non-digestible oligosaccharides are not digested in the gastrointestinal tract (GIT) using host enzymes (Den Besten et al, 2013).
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