Abstract
BackgroundGut microbiota provide functions of importance to influence hosts’ food digestion, metabolism, and protection against pathogens. Factors that affect the composition and functions of gut microbial communities are well studied in humans and other animals; however, we have limited knowledge of how natural food web factors such as stress from predators and food resource rations could affect hosts’ gut microbiota and how it interacts with host sex. In this study, we designed a two-factorial experiment exposing perch (Perca fluviatilis) to a predator (pike, Esox lucius), and different food ratios, to examine the compositional and functional changes of perch gut microbiota based on 16S rRNA amplicon sequencing. We also investigated if those changes are host sex dependent.ResultsWe showed that overall gut microbiota composition among individual perch significantly responded to food ration and predator presence. We found that species richness decreased with predator presence, and we identified 23 taxa from a diverse set of phyla that were over-represented when a predator was present. For example, Fusobacteria increased both at the lowest food ration and at predation stress conditions, suggesting that Fusobacteria are favored by stressful situations for the host. In concordance, both food ration and predation stress seemed to influence the metabolic repertoire of the gut microbiota, such as biosynthesis of other secondary metabolites, metabolism of cofactors, and vitamins. In addition, the identified interaction between food ration and sex emphasizes sex-specific responses to diet quantity in gut microbiota.ConclusionsCollectively, our findings emphasize an alternative state in gut microbiota with responses to changes in natural food webs depending on host sex. The obtained knowledge from this study provided us with an important perspective on gut microbiota in a food web context.
Highlights
Gut microbiota provide functions of importance to influence hosts’ food digestion, metabolism, and protection against pathogens
Tenericutes was the most abundant phylum, and it increased with food ration whereas the relative abundances of Fusobacteria and Proteobacteria seemed to a b c decrease with increasing food ration
When considering the interaction of factors, we found that Firmicutes and Fusobacteria had significantly more odds to respond than other phyla in the 10% food ration and pike presence interactions (Firmicutes: odds ratio = 6.27, p < 0.001, Fusobacteria: odds ratio = 20.68, p = 0.005)
Summary
Gut microbiota provide functions of importance to influence hosts’ food digestion, metabolism, and protection against pathogens. The intestine of most animals such as human and fish develops from an initial sterile environment, followed by a subsequent microbial colonization leading to a matured intestine inhabited by a diverse microbial community [2]. These microbiota help the hosts digest food, protect against pathogens, and influence the host’s metabolisms [3]. Bacteria differ in their substrate use; niche specialization in gut microbiota causes changes in bacterial taxa as a consequence of diet choice of the host [5]
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