Water system is a controlling variable modulating bacterial diversity of gastrointestinal tract and performance in rainbow trout

Abstract

A two-phase feeding study evaluating performance of rainbow trout and comparing luminal and mucosal gastrointestinal tract (GIT) bacterial community compositions when fed two alternative protein diets in two rearing systems was conducted. Alternative protein diets (animal protein and plant protein diets) balanced with crystalline amino acids: lysine, methionine and threonine or unbalanced, were fed to rainbow trout in two separate water systems (recirculating (RR) and flow-through (FF)) for a period of 16 weeks. The four diets, each contained 38% digestible protein and 20% fats, were fed to rainbow trout with an average weight of 12.02 ± 0.61 g, and sorted at 30 fish/tank and 12 tanks per dietary treatment. Phase 1 lasted for 8 weeks after which fish from each tank were randomly divided, with one-half moved to new tanks of the opposing system (i.e. from RR to FF and vice versa). The remaining halves were retained in their initial tank and system, and fed their original diets for another 8 weeks (phase 2). After the 16th week, 3 fish/tank were sampled for each of proximate analysis, body indexes and 16S rRNA analysis of GIT microbiota. Fish weight (P = 0.0008, P = 0.0030, P<0.0010) and body fat (P = 0.0008, P = 0.0041, P = 0.0177) were significantly affected by diet, diet quality (balanced or unbalanced) and system, respectively. Feed intake (P = 0.0008) and body energy (P<0.0010) were altered by system. Body indexes were not affected by dietary treatment and water systems. Compositional dissimilarities existed between samples from the rearing water and GIT locations (ANOSIM: (R = 0.29, P = 0.0010), PERMANOVA: R = 0.39, P = 0.0010), but not in dietary samples (ANOSIM: R = 0.004, P = 0.3140, PERMANOVA: R = 0.008, P = 0.4540). Bacteria were predominantly from the phyla Proteobacteria, Firmicutes and Bacteroidetes. Their abundance differed with more dissimilarity in the luminal samples (ANOSIM: R = 0.40, P = 0.0010, PERMANOVA: R = 0.56, P = 0.0010) than those from the mucosal intestine (ANOSIM: R = 0.37, P = 0.0010, PERMANOVA: R = 0.41, P = 0.0010). Bacteria generally associated with carbohydrate and certain amino acids metabolism were observed in the mucosal intestine while rearing water appeared to serve as the main route of colonization of Aeromonas and Acinetobacter in the rainbow trout.

Lactobacillus Dominate in the Intestine of Atlantic Salmon Fed Dietary Probiotics

“…Notwithstanding the fact that different extraction methods can cause small variations in the microbial profile (Wagner Mackenzie et al, 2015) studies have shown that rearing water has a minor effect on the GI microbiota in fish (Giatsis et al, 2015; Uren Webster et al, 2018). Betiku et al (2018) have demonstrated that recirculating water systems have more diverse microbial composition compared to the flow-through system. However, similar to other reports (Yan et al, 2016, Lokesh et al, 2018, Gupta et al, under review) water bacterial communities might not have affected the intestinal bacterial profile in our study.…”

Microbiota composition and intestinal integrity remain unaltered after the inclusion of hydrolysed Nannochloropsis gaditana in Sparus aurata diet

“…In the anterior and posterior sections it was observable genera like Clostridiales in Control-A but was not present in FH-A. In the posterior section, Enhydrobacter appearedin the treatment FH-P. Enhydrobacter is present in the microbiota of fish such as Dicentrarchus labrax and Salmo trutta 57 . It is known that this genus utilizes certain amino acids such as l -arginine, l -serine and l -alanine 58 , while some species present cellulase activity 57 , 59 .…”

“…In the posterior section, Enhydrobacter appearedin the treatment FH-P. Enhydrobacter is present in the microbiota of fish such as Dicentrarchus labrax and Salmo trutta 57 . It is known that this genus utilizes certain amino acids such as l -arginine, l -serine and l -alanine 58 , while some species present cellulase activity 57 , 59 . This fact may be of interest as cellulases hydrolyze the cellular wall of N. gaditana , allowing the fish to absorb the intracellular compounds of this algae.…”

Beneficial Shifts in the Gut Bacterial Community of Gilthead Seabream (Sparus aurata) Juveniles Supplemented with Allium-Derived Compound Propyl Propane Thiosulfonate (PTSO)

“…Furthermore, Büyükdeveci et al [ 20 ] showed an increase in body weight and a decrease in alpha diversity as the garlic concentration increased in the diet of rainbow trout ( O. mykiss ). However, another study on rainbow trout ( O. mykiss ) by Betiku et al [ 76 ] suggested that increased body weight is related to higher bacterial diversity. Although in our study, the general structure of bacterial community did not differ between the control and Allium -derived PTSO treatment, we found significant differences in the hindgut when the most abundant ASVs were taken into account.…”