Modulation of Atlantic salmon (Salmo salar) gut microbiota composition and predicted metabolic capacity by feeding diets with processed black soldier fly (Hermetia illucens) larvae meals and fractions

Abstract

Background Black soldier fly (Hermetia illucens) is a promising insect species to use as a novel ingredient in fish feeds. Black soldier fly larvae consists of three major fractions, namely protein, lipid, and exoskeleton. These fractions contain bioactive compounds that can modulate the gut microbiota in fish such as antimicrobial peptides, lauric acid, and chitin. However, it is not certain how, or which fractions of black solider fly would affect gut microbiota in fish. In the present study, black soldier fly larvae were processed into three different meals (full-fat, defatted and de-chitinized) and two fractions (oil and exoskeleton), and included in diets for Atlantic salmon (Salmo salar). Atlantic salmon pre-smolts were fed with these diets in comparison with a commercial-like control diet for eight weeks to investigate the effects of insect meals and fractions on the composition and predicted metabolic capacity of gut microbiota. The gut microbiota was profiled by 16S rRNA gene sequencing, and the predicted metabolic capacities of gut microbiota were determined using genome-scale metabolic models. Results The inclusion of insect meals and fractions decreased abundance of Proteobacteria and increased abundance of Firmicutes in salmon gut. The diets that contained insect chitin, i.e., insect meals or exoskeleton diets, increased abundance of chitinolytic bacteria including lactic acid bacteria and Actinomyces in salmon gut, with fish fed full-fat meal diet showing the highest abundances. The diets that contained insect lipids, i.e., insect meals and oil diets enriched Bacillaceae in fish gut. The fish fed diets containing full-fat insect meal had a unique gut microbiota composition dominated by beneficial lactic acid bacteria and Actinomyces, and showed a predicted increase in mucin degradation compared to the other diets. Conclusions The present results showed that the dietary inclusion of insect meals and fractions can differently modulate the composition and predicted metabolic capacity of gut microbiota in Atlantic salmon pre-smolts. The use of full-fat black soldier fly larvae meal in diets for salmon is more favorable for beneficial modulation of gut microbiota than larvae processed by separation of lipid or exoskeleton fractions.

Effects of Lysophospholipid Supplementation in Feed with Low Protein or Lipid on Growth Performance, Lipid Metabolism, and Intestinal Flora of Largemouth Bass (Micropterus salmoides)

“…Proteobacteria, Fusobacteria, and Firmicutes are widespread in the gut of aquatic organisms such as Nile tilapia ( Oreochromis niloticus ) [ 50 ], Atlantic salmon ( Salmo salar ) [ 51 ], and hybrid grouper [ 52 ]. Fusobacteria produces the short-chain fatty acid butyrate [ 53 ], which provides energy to gastrointestinal cells, increases mucus secretion, and has some growth-promoting effects [ 54 ].…”

From a cell model to a fish trial: Immunomodulatory effects of heat-killed Lactiplantibacillus plantarum as a functional ingredient in aquafeeds for salmonids

“…The total DNA of all digesta samples was extracted using QIAamp Fast DNA Stool Mini Kit (Qiagen, cat. #51604) according to the guidelines of the manufacturer as described previously ( 40 ). DNA from feed (with technical duplicate) and water from all the tanks was also extracted with the same methodology ( 40 ).…”

“…#51604) according to the guidelines of the manufacturer as described previously ( 40 ). DNA from feed (with technical duplicate) and water from all the tanks was also extracted with the same methodology ( 40 ). To ensure the reliability of the present workflow, blank samples were included during both extraction and sequencing, as well as DNA from a positive control with a known microbial community (catalog no.…”

“…Library was loaded at 8 pM and sequenced on the Miseq System using the Miseq Reagent Kit v3, 600-cycle (Illumina). Further information and scripts are described elsewhere ( 40 ). Briefly, the analysis of sequenced data was done in R 4.1.0 ( 41 ) with DADA2 1.18.0 package ( 42 ) to generate amplicon sequence variants (ASVs) with 22nt overlap.…”

“…After clustering by using VSEARCH algorithm and curated with LULU ( 45 ), 1593 unique ASVs and 515 identified taxonomic groups were identified, from which, 71.1% at the genus level. Alpha- and beta-diversities were calculated according with previous literature ( 39 , 40 ).…”