Dietary lipid content reorganizes gut microbiota and probiotic L. rhamnosus attenuates obesity and enhances catabolic hormonal milieu in zebrafish

Abstract

In the present study, we explored whether dietary lipid content influences the gut microbiome in adult zebrafish. Diets containing three different lipid levels (high [HFD], medium [MFD], and low [LFD]) were administered with or without the supplementation of Lactobacillus rhamnosus (P) to zebrafish in order to explore how the dietary lipid content may influence the gut microbiome. Dietary lipid content shifted the gut microbiome structure. The addition of L. rhamnosus in the diets, induced transcriptional reduction of orexigenic genes, upregulation of anorexigenic genes, and transcriptional decrease of genes involved in cholesterol and triglyceride (TAG) metabolism, concomitantly with lower content of cholesterol and TAG. Probiotic feeding also decreased nesfatin-1 peptide in HFD-P and attenuated weight gain in HFD-P and MFD-P fed zebrafish, but not in LFD-P group. Intestinal ultrastructure was not affected by dietary fat level or probiotic inclusion. In conclusion, these findings underline the role of fat content in the diet in altering gut microbiota community by shifting phylotype composition and highlight the potential of probiotics to attenuate high-fat diet-related metabolic disorder.

The zebrafish as a model for gastrointestinal tract–microbe interactions

“…It is advantageous due to its extremely high throughput and does not require much specialised equipment. More recently, the protozoan Paramecium caudatum, a natural prey for larval zebrafish, has been adapted as a vehicle for foodborne infection models (Fan et al, 2019;Flores et al, 2019;Stones et al, 2017). Immersion cannot be applied to strictly anaerobic microbes.…”

“…For some GI pathogens, in particular those for which zebrafish are not a natural host, immersion does not lead to robust intestinal colonisation (e.g., Tysnes, Jørgensen, Poppe, Midtlyng, & Robertson, 2012;Stones et al, 2017 etc.). More recently, the protozoan Paramecium caudatum, a natural prey for larval zebrafish, has been adapted as a vehicle for foodborne infection models (Fan et al, 2019;Flores et al, 2019;Stones et al, 2017). The protozoan internalises bacteria into storage vacuoles, and following uptake of Paramecia by the zebrafish and degradation of the protozoan in the foregut, the bacterial load is released into the middle intestine.…”

“…The successful colonisation of the larval gut with anaerobic species, including Lactobacillus paracasei and strict anaerobes such as Eubacterium limosum and Akkermansia muciniphila, in particular, was an important stepping stone in establishing zebrafish as a surrogate host for studies on the human gut microbiome (Arias-Jayo et al, 2018; Toh et al, 2013).The emerging consumer interest in probiotics as a supplement to promote health and well-being has further propelled microbiome studies in zebrafish. Colonisation of adult zebrafish with the probiotic L. rhamnosus decreases the expression of host genes associated with dietary lipid metabolism(Falcinelli et al, 2017). In zebrafish, L. plantarum protects against stress-induced dysbiosis of the gut microbiota and ameliorates anxiety-related behaviour.…”

“…The lactic acid bacteria L. plantarum is of particular interest and is currently commercialised as a beneficial probiotic that alleviates stress and anxiety in humans(Chong et al, 2019). Consequently, shifts in microbiome community structures resulting from high dietary fat intake and associated weight gain are ameliorated by supplementation with L. rhamnosus, highlighting its potential to attenuate dietrelated metabolic disorder(Falcinelli et al, 2017).6 | ZEBRAFISH MODELS OF INFLAMMATORY BOWEL DISEASESWhile the aetiologies of multifactorial IBDs like ulcerative colitis and Crohn's disease are unknown, two key features of the pathology are intestinal epithelial damage and intestinal dysbiosis. These changes in microbiome composition and behaviour correlate with an increase in expression of gamma-aminobutyric acid receptors and of serotonin transporters in zebrafish brains following administration of L. plantarum(Davis et al, 2016).…”

Kluyveromyces fragilisRNA extract supplementation promotes growth, modulates stress and inflammatory response in zebrafish

“…Several studies focused their attention on the use of bacteria as probiotics and their capability to modify host nutrient metabolism and energy balance (Falcinelli et al., , , ; Hemarajata & Versalovic, ; Maradonna et al., ); however, last evidences have shown that many eukaryotic species, such as yeasts and yeast nucleotides, positively regulate host metabolism (Ringø, Erik Olsen, Gonzalez Vecino, Wadsworth, & Song, ).…”