Synbiotic Effects of Saccharomycescerevisiae, Mannan Oligosaccharides, and β-Glucan on Innate Immunity, Antioxidant Status, and Disease Resistance of Nile Tilapia, Oreochromis niloticus

Serum proteinogram of gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) as a new useful approach for detecting loss of haemostasis

Proteinograms, a semiquantitative analytical method that separates proteins into multiple bands, have not been explored in teleosts for diagnostic or prognostic purposes. This study aimed to establish reference values for proteinograms in the serum of gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax), two important farmed fish species in the Mediterranean region. Serum proteins were studied using SDS-PAGE, electropherogram, and HPLC-mass spectrometry. SDS-PAGE analysis revealed four major bands of proteins around 11, 25, 70, and 100 kDa in the serum of gilthead seabream and European seabass. Electropherogram results showed that a protein with a molecular weight of 76.8 kDa was the most abundant protein in the serum of gilthead seabream, while a peak of 75.5 kDa was the most abundant in European seabass. HPLC-mass spectrometry detected 87 proteins and 119 proteins in the serum of gilthead seabream and European seabass, respectively, including α1-globulins, α2-globulins, β-globulins, and γ-globulins. Notably, the albumin sequence was not detected in either of the two species. These results help to characterise the serum protein profile and to establish reference proteinograms for these two fish species. They also provide a basis for the development of novel approaches for the rapid detection of loss of haemostasis due to stress, health disorders or disease in farmed fish.

Combined Effects of Yellow Mealworm (Tenebrio molitor) and Saccharomyces cerevisiae on the Growth Performance, Feed Utilization Intestinal Health, and Blood Biomarkers of Nile Tilapia (Oreochromis niloticus) Fed Fish Meal-Free Diets

Aquafeed quality is the most critical factor for aquaculture sustainability. However, limitations of traditional feed ingredients such as fishmeal (FM) need alternative strategies to ensure the nutritional requirements for aquatic animals. In this trial, four test diets were formulated (2 × 2 factorial design), where FM was incorporated in two diets at 10% with or without Saccharomyces cerevisiae (SC) at 1 g/kg. At the same time, FM was replaced with yellow mealworm (Tenebrio molitor) meal (TM) with or without SC at 1 g/kg. The growth performance indices (final weight, weight gain, and SGR), and the feed utilization indices (FCR and PER) were markedly affected by the protein source (FM or TM) and dietary SC (P < 0.05). The protein source (FM or TM) significantly (P < 0.05) affected the whole-body protein and lipid contents, while the moisture and ash contents were unaffected (P > 0.05) by TM or SC. The growth of the intestinal villi showed a marked increase in both height and branching in the treated groups with SC along the whole length of the intestine. Furthermore, the immune cell infiltration was prominent near the intestinal crypts of the middle intestinal segments in the supplemented groups by SC. Dietary TM and SC revealed improved hepatic parenchyma in the liver tissue better than other groups. The hematological indices, including hemoglobulin, hematocrit, red blood cells, and white blood cells, were markedly affected by dietary SC (P < 0.05). The lysozyme activity and phagocytic index were markedly affected by dietary SC, while phagocytic activity was affected by dietary TM (P < 0.05). The catalase, glutathione peroxidase, and malondialdehyde were markedly affected by the interaction between dietary protein source and SC, while superoxide dismutase was affected by dietary SC (P < 0.05). In conclusion, adding SC could enhance the utilization of TM by Nile tilapia with positive effects on the intestinal and liver histological features and the immune and antioxidative responses.

Synbiotic Agents and Their Active Components for Sustainable Aquaculture: Concepts, Action Mechanisms, and Applications

Aquaculture is a fast-emerging food-producing sector in which fishery production plays an imperative socio-economic role, providing ample resources and tremendous potential worldwide. However, aquatic animals are exposed to the deterioration of the ecological environment and infection outbreaks, which represent significant issues nowadays. One of the reasons for these threats is the excessive use of antibiotics and synthetic drugs that have harmful impacts on the aquatic atmosphere. It is not surprising that functional and nature-based feed ingredients such as probiotics, prebiotics, postbiotics, and synbiotics have been developed as natural alternatives to sustain a healthy microbial environment in aquaculture. These functional feed additives possess several beneficial characteristics, including gut microbiota modulation, immune response reinforcement, resistance to pathogenic organisms, improved growth performance, and enhanced feed utilization in aquatic animals. Nevertheless, their mechanisms in modulating the immune system and gut microbiota in aquatic animals are largely unclear. This review discusses basic and current research advancements to fill research gaps and promote effective and healthy aquaculture production.

Effects of Dietary Pectin and Lactobacillus salivarius ATCC 11741 on Growth Performance, Immunocompetence, Gut Microbiota, Antioxidant Capacity, and Disease Resistance in Narrow-Clawed Crayfish, Postantacus leptodactylus

The present study was conducted to clarify the effects of Lactobacillus salivarius (LS) ATCC 11741 and pectin (PE) on growth performance, digestive enzymes activity, gut microbiota composition, immune parameters, antioxidant defense as well as disease resistance against Aeromonas hydrophila in narrow-clawed crayfish, Postantacus leptodactylus. During 18 weeks trial feeding, 525 narrow-clawed crayfish juvenile (8.07 ± 0.1 g) fed with seven experimental diets including control (basal diet), LS1 (1 × 10⁷ CFU/g), LS2 (1 × 109 CFU/g), PE1 (5 g/kg), PE2 (10 g/kg), LS1PE1 (1 × 10⁷ CFU/g +5 g/kg), and LS2PE2 (1 × 109 CFU/g +10 g/kg). After 18 weeks, growth parameters (final weight, weight gain, and specific growth rate) and feed conversion rate were significantly improved in all treatments (P < 0.05). Besides, diets incorporated with LS1PE1 and LS2PE2 significantly increased the activity of amylase and protease enzymes compared to LS1, LS2, and control groups (P < 0.05). Microbiological analyses revealed that the total heterotrophic bacteria count (TVC) and lactic acid bacteria (LAB) of narrow-clawed crayfish fed diets containing LS1, LS2, LS1PE1, and LS2PE2 were higher than control group. The highest total haemocyte count (THC), large-granular (LGC) and semigranular cells (SGC) count, and hyaline count (HC) was obtained in LS1PE1 (P < 0.05). Similarly, higher immunity activity (lysozyme (LYZ), phenoloxidase (PO), nitroxidesynthetase (NOs), and alkaline phosphatase (AKP)) observed in the LS1PE1 treatment compared to the control group (P < 0.05). The glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity remarkably enhanced in LS1PE1 and LS2PE2, while malondialdehyde (MDA) content reduced in these two treatments. In addition, specimens belonging to LS1, LS2, PE2, LS1PE1, and LS2PE2 groups presented higher resistance against A. hydrophila compared to the control group. In conclusion, feeding narrow-clawed crayfish with synbiotic had higher efficiency on growth parameters, immunocompetence, and disease resistance compared to single consumption of prebiotics and probiotics.

Synbiotic Lactic Dry® enhanced the growth performance, growth-related genes, intestinal health, and immunity of Nile tilapia reared in inland brackish groundwater

Nile tilapia is recognized as a suitable candidate for intensive farming and sustainability of the aquaculture industry. However, one issue limiting Nile tilapia expansion in arid and semi-arid areas is the scarcity of freshwater resources. In this study, the supplementation of synbiotics was investigated to enhance the growth performance, growth-related genes, intestinal health, and immunity of Nile tilapia reared in inland brackish groundwater. Four diets were prepared where the basal diets were mixed with the dietary mixture of probiotics and prebiotics (Synbiotic Lactic Dry®, a blend of Saccharomyces cerevisiae, Lactobacillus acidophilus, Streptococcus faecium, and Bacillus subtilis, mannan oligosaccharides and β-1.3/1.6-D-glucan) at 0, 0.5, 1, and 2 g/kg. After eight weeks, the final weight and weight gain are linearly increasing with increasing the supplementation level of synbiotic. Markedly fish fed 0.5, 1, and 2 g/kg of synbiotic had higher final weight, weight gain, and feed intake and lower feed conversion ratio (FCR) than fish fed synbiotic free diet. The specific growth rate (SGR) was significantly higher in fish fed 1 and 2 g/kg than in fish fed 0 and 0.5 g/kg. The intestine of fish fed on synbiotic shows an increase in intestinal villi density. Further, the intestine of fish fed on synbiotic showed an increase in the length and branching intestinal villi (anterior, middle, and posterior) in a dose-dependent manner. The lysozyme and phagocytic activities were significantly different from the control, while synbiotic supplementation did not affect the phagocytic index. Interestingly, the results showed marked upregulation of ghrelin, IGF-1, and GH genes in fish fed synbiotics at 0.5, 1, and 2 g/kg. In addition, fish fed 2 g/kg had the highest expression of ghrelin, IGF-1, and GH genes. In conclusion, growing Nile tilapia in inland brackish groundwater can be achieved without negative impacts on the growth performance and health status. Supplementing synbiotics (1-2 g/kg) in Nile tilapia feeds enhanced the growth and feed performances, intestinal histomorphological features, growth-related genes, and immune response.

Low-dose dexamethasone in combination with luteolin improves myocardial infarction recovery by activating the antioxidative response

This study aimed to explore the effects of dexamethasone (DEX) and its combination with luteolin (LUT) on cardiac function during myocardial infarction (MI) in a mouse model. We evaluated whether the Keap1/Nrf2 pathway mediates the cardioprotective function of DEX both in vivo and in vitro. The MI mouse model was established by ligation of the left anterior descending coronary artery of wild-type (WT) and Nrf2 knockout mice. After recovery for 21 days, DEX or its combination with LUT was intraperitoneally administered at different doses to WT or Nrf2 knockout mice daily for 7 consecutive days. Mice treated with DEX at a low dose (50 μg/kg/day) showed better cardiac function, fewer cardiac lesions, and smaller infarct sizes compared with MI model mice. DEX (50 μg/kg/day) administration also significantly decreased the production of reactive oxygen species (ROS) and pro-inflammatory cytokines, increased the expression of antioxidative enzymes, and activated the Keap1/Nrf2/HO-1 pathway. However, in Nrf2 knockout mice, DEX treatment did not influence cardiac function, inflammation, the oxidative response, or Keap1/Nrf2/HO-1 activation. In the MI cell model, low concentrations of DEX attenuated the H₂O₂-induced decreases in cell viability and antioxidative enzyme levels and activated the Keap1/Nrf2/HO-1 pathway. Low doses of DEX exerted protective effects in MIR mice and MI cell models by improving cardiac function, eliminating ROS, inhibiting inflammatory responses, and activating antioxidative responses. The protective effects of DEX on myocardial tissues were mediated by the Keap1/Nrf2/HO-1 pathway.

Probiotics, prebiotics and synbiotics improved the functionality of aquafeed: Upgrading growth, reproduction, immunity and disease resistance in fish

Aquaculture plays an increasingly significant role in improving the sustainability of global fish production. This sector has been intensified with the advent of new husbandry practices and the development of new technology. However, the increasing intensification and indiscriminate commercialized farming has enhanced the vulnerability of cultivated aquatic species to damage from pathogens. In efforts to confront these various diseases, frequent use of drugs, antibiotics, chemotherapeutics, and agents for sterilization have unintentionally added to the risk of transmission of pathogens and harmful chemical compounds to consumers. Some natural dietary supplements are believed to have the potential to offset this setback in aquaculture. Application of bio-friendly feed additives such as probiotics, prebiotics and synbiotics are becoming popular dietary supplements with the potential to not only improve growth performance, but in some cases can also enhance immune competence and the overall well-being of fish and crustaceans. The present review discusses and summarizes the effects of probiotics, prebiotics and synbiotics application on growth, stress mitigation, microbial composition of intestine, immune system and health condition of aquatic animals in association with existing constraints and future perspectives in aquaculture.

In vitro Selection of Synbiotics and in vivo Investigation of Growth Indices, Reproduction Performance, Survival, and Ovarian Cyp19α Gene Expression in Zebrafish Danio rerio

In this study, we tested the compatibility of two extracts from the plant Jerusalem artichokes and button mushrooms with two different Lactobacillus probiotics (Lactobacillus acidophilus; La and Lactobacillus delbrueckii subsp. Bulgaricus; Lb) to develop a synbiotic formulation to improve the growth, survival, and reproductive performances of farmed fishes. Initially, we employed in vitro approach to monitor the growth of the probiotic lactobacilli in the presence of the different doses of the plant-based prebiotics, with the aim of selecting interesting combination(s) for further verification under in vivo conditions using zebrafish as a model. Results from the in vitro screening assay in the broth showed that both the probiotic species showed a preference for 50% mushroom extract as a source of prebiotic. A synbiotic formulation, developed with the selected combination of L. acidophilus, L. bulgaricus, and 50% mushroom extract, showed a positive influence on the growth and reproductive performances of the zebrafish. Our findings also imply that the improvement in the reproductive indices was associated with the upregulation of a cyp19a gene. Overall results suggest that a combination of L. acidophilus, L. bulgaricus, and mushroom extract can be considered as a potential synbiotic for the successful production of aquaculture species.