Low fish meal diet supplemented with probiotics ameliorates intestinal barrier and immunological function of Macrobrachium rosenbergii via the targeted modulation of gut microbes and derived secondary metabolites

Abstract

The unsuitable substitution ratio of fish meal by plant protein will reshape the intestinal microbial composition and intestine immunity. However, previous studies were mostly limited to investigating how different feed or probiotics characterized the microbial composition but ignored the biological interactions between bacteria and host physiology through secondary metabolites. Therefore, this study integrates the apparent indicators monitoring, 16S rDNA sequencing, and metabonomics to systematically investigate the effects of cottonseed protein concentrate (CPC) substitution of fish meal and Bacillus coagulans intervention on gut microbes, secondary metabolites, and intestinal immunity of Macrobrachium rosenbergii. Prawns were fed with three diets for 70 days: HF diets contained 25% fish meal, CPC in LF diets were replaced with 10% fish meal, and LF diets supplemented with 2 × 108 CFU/g diet B. coagulans were designated as BC diets. Results showed that CPC substitution induced a significant decrease in digestive enzyme activities (trypsin and lipase) and gut barrier protein PT-1 expression and a significant increase in γ-GT enzyme activity and inflammatory-related factors (Relish and Toll) expression. B. coagulans treatment mitigated the negative changes of the above indicators. Meanwhile, it significantly improved the expression levels of the barrier factor PT-1, the reparative cytokine IL-22, and Cu/Zn-SOD. CPC substitution resulted in a remarkable downregulated abundance of Firmicutes phyla, Flavobacterium spp., and Bacillus spp. B. coagulans treatment induced the callback of Firmicutes abundance and improved the relative abundance of Sphingomonas, Bacillus, and Ralstonia. Functional prediction indicated that CPC substitution resulted in elevated potential pathogenicity of microbial flora, and B. coagulans reduces the pathogenesis risk. Pearson’s correlation analysis established a significant positive correlation between differential genera (Sphingomonas, Bacillus, and Ralstonia) and secondary metabolites (including sphingosine, dehydrophytosphingosine, amino acid metabolites, etc.). Meanwhile, the latter were significantly associated with intestinal immunoregulation-related genes (Cu/Zn-SOD, IL-22, PT-1, Toll, and Relish). This study indicated that B. coagulans could mediate specific gut microbes and the combined action of multiple functional secondary metabolites to affect intestinal barrier function, digestion, and inflammation. Our study revealed the decisive role of gut microbes and derived secondary metabolites in the model of dietary composition-induced intestinal injury and probiotic treatment from a new perspective.

Utilisation of probiotics for disease management in giant freshwater prawn (Macrobrachium rosenbergii): Administration methods, antagonistic effects and immune response

“…Recent advances in high‐throughput sequencing techniques enable studying the impact of probiotics on prawn‐associated microbiomes. Some recent studies reported shifts in the prawn‐associated microbiota after probiotic treatment (Cienfuegos‐Martínez et al, 2022; Qiu et al, 2023; Zheng et al, 2022). However, in order to determine whether probiotics have a beneficial impact on the prawn microbiome, we first need to obtain a better understanding of what can be considered a healthy prawn microbiome (by analysing microbiomes of healthy and diseased prawns grown in different culture systems).…”

“…Recent advances in high-throughput sequencing techniques enable studying the impact of probiotics on prawn-associated microbiomes. Some recent studies reported shifts in the prawnassociated microbiota after probiotic treatment (Cienfuegos-Martínez et al, 2022;Qiu et al, 2023;Zheng et al, 2022). However, in order to determine whether probiotics have a beneficial impact…”

Probiotic Bacillus licheniformis ZW3 Alleviates DSS-Induced Colitis and Enhances Gut Homeostasis

“…Our previous research showed an extremely high cure rate (over 95%) against newborn calves’ diarrhea with Bacillus velezensis JT3-1, a probiotic isolated from yak feces [ 16 ]. Studies on broilers [ 17 ] and prawns [ 18 ] indicated that Bacillus can promote animal growth performance, intestinal inflammation, and oxidative stress by regulating specific gut microbes. As such, specific Bacillus is a promising probiotic in the aquaculture industry.…”

Differential Immune-Modulating Activities of Cell Walls and Secreted Metabolites from Probiotic Bacillus coagulans JBI-YZ6.3 under Normal versus Inflamed Culture Conditions

“…The immune-activating properties of probiotic cell walls are well documented, where the activation of host defenses includes the engagement of pattern recognition receptors (PPRs) on immune cells [21,22]. In addition, the metabolites secreted by B. coagulans have a variety of beneficial effects on the host (Table 1), including the increased production of mucin and tight junction proteins that protect the epithelial barrier [23][24][25][26], apoptosisinducing substances that contribute to the destruction of cancer cells [27,28], antimicrobial peptides such as bacteriocin [29][30][31], and the fatty acid-mediated [32][33][34][35] and surfactantsmediated inhibition of pathogens [36,37], which prevent the formation of pathogenic biofilms. Furthermore, the metabolites stimulate the immune response by enhancing macrophage activity and modulating the secretion of immunoglobulins [38][39][40].…”