Abstract
Plant-derived protein sources are the most relevant substitutes for fishmeal in aquafeeds. Nevertheless, the effects of plant based diets on the intestinal microbiome especially of juvenile Rainbow trout (Oncorhynchus mykiss) are yet to be fully investigated. The present study demonstrates, based on 16S rDNA bacterial community profiling, that the intestinal microbiome of juvenile Rainbow trout is strongly affected by dietary plant protein inclusion levels. After first feeding of juveniles with either 0%, 50% or 97% of total dietary protein content derived from plants, statistically significant differences of the bacterial gut community for the three diet-types were detected, both at phylum and order level. The microbiome of juvenile fish consisted mainly of the phyla Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria and Actinobacteria, and thus fits the salmonid core microbiome suggested in previous studies. Dietary plant proteins significantly enhanced the relative abundance of the orders Lactobacillales, Bacillales and Pseudomonadales. Animal proteins in contrast significantly promoted Bacteroidales, Clostridiales, Vibrionales, Fusobacteriales and Alteromonadales. The overall alpha diversity significantly decreased with increasing plant protein inclusion levels and with age of experimental animals. In order to investigate permanent effects of the first feeding diet-type on the early development of the microbiome, a diet change was included in the study after 54 days, but no such effects could be detected. Instead, the microbiome of juvenile trout fry was highly dependent on the actual diet fed at the time of sampling.
Highlights
With increasing knowledge about the impact of the gut microbiome on human health and nutritional status, an increase in studies about the fish microbiome can be observed, which is especially promoted by the availability of new technologies [2]
Fusobacteria and Bacteroidetes played an important role in the fermentation of plant material in Common carp (Cyprinus carpio) [4] and Firmicutes found in the gastro-intestinal (GI) tract of Grass carp (Ctenopharyngodon idellus) could utilize various polysaccharides, such as cellulose, xylan and hemicelluloses [5]
A recent study [18] demonstrated that first feeding initializes the colonization of the gut in Rainbow trout fry, but the subsequent development of the bacterial community structure is influenced by the diet-type
Summary
With increasing knowledge about the impact of the gut microbiome on human health and nutritional status (see review by the Human Microbiome Project Consortium [1]), an increase in studies about the fish microbiome can be observed, which is especially promoted by the availability of new technologies [2]. Even though the importance of dietary effects on the gastro-intestinal microbiome of fish has been demonstrated in several publications, as reviewed by Ringø et al [16], little is known on how early feeding of plant proteins is affecting the developing intestinal microbiome of juvenile carnivores It has been shown for amberjack juveniles (Seriola dumerili) fed diets supplemented with soybean meal that the inclusion of heat-killed Lactobacillus plantarum has a positive impact on the utilization of dietary soybean meal [17], which implies interactions between the intestinal microbiota and the utilization of plantderived protein sources. The purpose of the current study was to evaluate effects of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
