Immobilizing yeast β-glucan on zinc-layered hydroxide nanoparticle improves innate immune response in fish leukocytes

Bacterial diseases of Asian sea bass (Lates calcarifer): A review for health management strategies and future aquaculture sustainability

The advent of aquaculture has been one of the most significant shifts in world food supply during the last century. Aquaculture has rapidly expanded and become a global food industry, spurred by population expansion, increased seafood consumption, and decreased captured fisheries. Nonetheless, the exponential growth of aquaculture has emerged as a significant contributor to anthropogenic changes. Unexpectedly, the result has focused in the emergence and spread of new diseases. The Asian sea bass (Lates calcarifer) is an economically important species in aquaculture, contributing significantly to the global seafood market. However, bacterial diseases have emerged as a major concern, affecting both wild and cultured populations of this species. The most prevalent bacterial pathogens are streptococcus, vibriosis, nocardiosis, tenacibaculosis, and pot-belly disease. Therefore, this review aims to comprehensively analyze both emerging and non-emerging bacterial diseases affecting L. calcarifer and explore potential management approaches for their control. Through an extensive literature survey and critical evaluation of research findings, this review highlights the current understanding of bacterial diseases in L. calcarifer and proposes strategies for better disease management. In addition, this review looks at the rise and characteristics of aquaculture, the major bacterial pathogens of L. calcarifer and their effects, and the specific attributes of disease emergence in an aquatic rather than terrestrial context. It also considers the potential for future disease emergence in L. calcarifer due to aquaculture expansion and climate changes.

Addition of β-glucans in diets for tropical gar (Atractosteus tropicus) larvae: effects on growth, digestive enzymes and gene expression of intestinal epithelial integrity and immune system

The effect of β-glucans 1,3/1,6 from Saccharomyces cerevisiae yeast at different inclusion percentages (0.0, 0.2, 0.4, 0.6, and 0.8%) in the diet for tropical gar (Atractosteus tropicus) larvae was evaluated on growth, digestive enzyme activity and, relative expression of the immune system genes. The bioassay started on the third day after hatching (DAH) and lasted 21 days, using a total of 1500 larvae of 0.055 ± 0.008 g and, a total length of 2.46 ± 0.26 cm. Larviculture was carried out in a recirculation system with 15 tanks of 70 L using a density of 100 organisms per experimental unit. No significant differences in larval growth were observed by the inclusion of β-glucans (p > 0.05). Digestive enzymes showed changes in lipase and trypsin activities, presenting higher values in fish fed 0.6% and 0.8% β-glucans diets compared to the other treatments (p < 0.05). Leucine-aminopeptidase, chymotrypsin, acid phosphatase, and alkaline phosphatase activity showed higher activities in larvae fed with a 0.4% β-glucan diet compared to the control group. The relative expression of intestinal membrane integrity (mucin 2) muc-2, (occludins) occ, (nucleotide-binding oligomerization domain) nod-2, and immune system lys (lysosome) genes showed over-expression in larvae fed the 0.4% β-glucan diet to the rest of the treatments (p < 0.05). The inclusion of β-glucans at 0.4-0.6% in diets for A. tropicus larvae could improve larviculture, as effects on the increase in the activity of several digestive enzymes and the expression of genes of the immune system.

An important polysaccharide from fermentum

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Extraction, structure and modification of polysaccharides from fermentum were summarized.

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Structure-activity relationship and application of polysaccharides from fermentum were reviewed.

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It provided a strong basis for the development and application of polysaccharides from fermentum.

Fermentum is a common unicellular fungus with many biological activities attributed to β-polysaccharides. Different in vivo and in vivo experimental studies have long proven that fermentum β-polysaccharides have antioxidant, anti-tumor, and fungal toxin adsorption properties. However, there are many uncertainties regarding the relationship between the structure and biological activity of fermentum β-polysaccharides, and a systematic summary of fermentum β-polysaccharides is still lacking. Herein, we reviewed the research progress about the extraction, structure and modification, structure–activity relationship, activity and application of fermentum β-polysaccharides, compared the extraction methods of fermentum β-polysaccharide, and paid special attention to the structure–activity relationship and application of fermentum β-polysaccharide, which provided a strong basis for the development and application of fermentum β-polysaccharide.

Nanohybrid of Thymol and 2D Simonkolleite Enhances Inhibition of Bacterial Growth, Biofilm Formation, and Free Radicals

Due to the current concerns against opportunistic pathogens and the challenge of antimicrobial resistance worldwide, alternatives to control pathogen growth are required. In this sense, this work offers a new nanohybrid composed of zinc-layered hydroxide salt (Simonkolleite) and thymol for preventing bacterial growth. Materials were characterized with XRD diffraction, FTIR and UV–Vis spectra, SEM microscopy, and dynamic light scattering. It was confirmed that the Simonkolleite structure was obtained, and thymol was adsorbed on the hydroxide in a web-like manner, with a concentration of 0.863 mg thymol/mg of ZnLHS. Absorption kinetics was described with non-linear models, and a pseudo-second-order equation was the best fit. The antibacterial test was conducted against Escherichia coli O157:H7 and Staphylococcus aureus strains, producing inhibition halos of 21 and 24 mm, respectively, with a 10 mg/mL solution of thymol–ZnLHS. Moreover, biofilm formation of Pseudomonas aeruginosa inhibition was tested, with over 90% inhibition. Nanohybrids exhibited antioxidant activity with ABTS and DPPH evaluations, confirming the presence of the biomolecule in the inorganic matrix. These results can be used to develop a thymol protection vehicle for applications in food, pharmaceutics, odontology, or biomedical industries.

Yeast β-Glucans as Fish Immunomodulators: A Review

Simple Summary

The β-glucan obtained from yeast—a very important molecule for fish production—activates the immune system of fish by different mechanisms and induces protection against pathogens. However, most previous related studies have focused on the use of commercial β-glucan from the yeast Saccharomyces cerevisiae to understand the activation pathways. Experimental β-glucans extracted from other yeasts show other interesting biological activities even at lower doses. This review article analyzes the current information and suggests perspectives on yeast β-glucans.

Abstract

Administration of immunostimulants in fish is a preventive method to combat infections. A wide variety of these biological molecules exist, among which one of the yeast wall compounds stands out for its different biological activities. The β-glucan that forms the structural part of yeast is capable of generating immune activity in fish by cell receptor recognition. The most frequently used β-glucans for the study of mechanisms of action are those of commercial origin, with doses recommended by the manufacturer. Nevertheless, their immune activity is inefficient in some fish species, and increasing the dose may show adverse effects, including immunosuppression. Conversely, experimental β-glucans from other yeast species show different activities, such as antibacterial, antioxidant, healing, and stress tolerance properties. Therefore, this review analyses the most recent scientific reports on the use of yeast β-glucans in freshwater and marine fish.

Biocompatible Nanomaterials in Food Science, Technology, and Nutrient Drug Delivery: Recent Developments and Applications

Nanomaterials exist as potential biocompatible materials in nature and are being synthesized to provide extraordinary characteristics in various food industry sectors. Synthesis of biocompatible nanomaterials requires modification in the shape, density, and size of nanomaterials. Biocompatible nanomaterials are synthesized to reduce toxicity, decrease adverse effects in the gastrointestinal tract, and enhance immune response. Nanomaterials can target organs and tissues. Nanomaterials are found to be effectively compatible by interacting with functional foods and nutraceuticals. Applications of these nanomaterials are novel strategies in food industries such as food safety, food processing, food quality, food packaging, and food labeling. Various functions like detection of toxins and pathogens; production of biocompatible packaging; enhancement in color, flavor, and aroma; processing edible film, and sensing authenticity of food product are being accomplished with no toxicity. This review provides a systematic study on the biocompatibility of nanomaterials. It highlights the synthesis of biocompatible nanomaterials and advanced functions of these nanomaterials in the production area, processing industry, safety improvement, quality control, edible packaging films, biocompatibility, current developments, legislations and regulations for Nano-products, health and safety concerns, toxicity and public perceptions for use of nanomaterials.

β-glucan as a promising food additive and immunostimulant in aquaculture industry

The use of antibiotics in aquatic feed reduces the incidence of disease and enhances growth performance, although it presents harmful effects, such as development of resistant bacteria and accumulation in the natural environment. A variety of immune stimulants including probiotics, prebiotics, synbiotics, phytobiotics, organic acids, nucleotides, antioxidants, microalgae, yeast and enzymes have been used in the aquaculture industry. In recent decades, much attention has been paid on finding a variety of immunostimulants with lower cost which also affect specific and non-specific immunity and improve fish resistance against a wide range of pathogens. These stimulants strengthen the fish’s immune system by increasing the number of phagocytes, lysozyme activity and level of immunoglobulin. The use of immune stimulants as an effective tool to overcome diseases and strengthen the immune system of farmed species, leads to the promotion of cellular and humoral defense mechanisms and increases resistance to infectious diseases. Among these immunostimulants used in aquaculture, β-glucans are of particular importance. Glucans are complex polysaccharide compounds extracted from the cell wall of yeasts and fungi. These compounds can stimulate fish growth, survival, and immune function. Therefore, this review discusses the role and importance of β-glucan as a food additive in aquaculture and examines the impact of these compounds on the growth performance, immunity and biochemical parameters of farmed species.

Effects of Apple (Malus pomila) Pomace-Derived Pectin on the Innate Immune Responses, Expressions of Key Immune-Related Genes, Growth Performance, and Digestive Enzyme Activity of Rainbow Trout (Oncorhynchus mykiss)

Simple Summary

The present study investigated possible administration of pectin derived from apple pomace as a beneficial and cost-effective feed additive to be used in trout culture. To achieve the aim, a range of parameters were measured including immune parameters (both at physiological and molecular levels), growth performance and digestive enzyme activity. The results showed promising effects on the measured parameters and hence we can suggest administration of this feed additive in trout culture.

Abstract

Pectins are a group of carbohydrates found in structural parts of terrestrial plants with wide industrial and biomedical applications. This study was designed to investigate the dietary effects of apple pomace-derived pectin (APDP) in rainbow trout (Oncorhynchus mykiss). Four formulated diets were provided with different inclusion levels of APDP for 30 days: 0, 5, 10, and 20 g kg⁻¹; referred to as control, P1, P2, and P3, respectively. In this study, 300 fish (3.56 ± 0.007 g) were randomly distributed into twelve fiberglass tanks and fed 3% of their respective body weight four times a day. At the end of the experiment, growth parameters, including weight gain, specific growth rate, and food conversion ratio (FCR) were significantly improved in P1 and P2 treatments compared to those of the other treatments. Results from proximate composition analysis showed that protein content increased, and lipid decreased in the P2 and P3 groups. Serum lysozyme, complement activity, total immunoglobulin levels, and total protein were significantly enhanced in all treatments compared to those of the control group. Gene expression results showed no significant difference in regulation of interleukin-1β (IL-1β); however, up-regulation of lysozyme, interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) was observed in both P1 and P2. Unlike lipase, the activity of protease and amylase significantly increased in fish receiving different levels of APDP compared to the control (p < 0.05). In conclusion, the present findings suggest APDA as a promising feed additive for rainbow trout.

Probiotic and Immunomodulatory Activity of Marine Yeast Yarrowia lipolytica Strains and Response Against Vibrio parahaemolyticus in Fish

Yarrowia lipolytica has been widely used in food industry but scarcely explored as probiotics. Thus, the aims of this study were to characterize in vitro the probiotic potential, antioxidant capacity, and antimicrobial activity of the marine yeast Y. lipolytica D-1 and N-6 strains. Dietary administration effect was evaluated in vivo on immunological parameters in serum, skin-mucus, intestine, and fish leukocytes upon challenge with Vibrio parahaemolyticus. The results showed that Y. lipolytica D-1 and N-6 strains grew with NaCl or bile salts but were sensitive to low pH. Each of the Y. lipolytica strains had a distinctive antioxidant capacity and fatty acid profile, but their antimicrobial activity was similar against fish bacterial pathogens. Fish (Lutjanus peru) supplemented with Y. lipolytica strains showed normal intestinal morphology, high IgM levels, and antioxidant enzyme activities. Immune-related genes were modulated in fish fed Y. lipolytica in a strain-dependent fashion. In addition, leucocytes from fish fed Y. lipolytica challenged with V. parahaemolyticus increased innate immune and antioxidant parameters compared with the control groups. In conclusion, the marine yeast Y. lipolytica D-1 and N-6 strains may be potential probiotics for fish by exerting free-radical scavenging, antimicrobial activity, and improved immune-protective responses against V. parahaemolyticus infection.

Yarrowia lipolytica N6-glucan protects goat leukocytes against Escherichia coli by enhancing phagocytosis and immune signaling pathway genes

Immunostimulant and protective effects of Yarrowia lipolytica glucans against important pathogens, such as Escherichia coli, have not been investigated in goats and other ruminants. This study aimed to characterize Y. lipolytica N6-glucan (Yl-glucan) and its possible role in immunological signaling pathway activation and immunoprotection against E. coli in goat leukocytes. Characterization analyses showed that Y. lipolytica content had a mix of β and α-D-glucans, molecular weight of 3301.53 kDa and low solubility after the heat treatment. The stimulation of goat leukocytes with Yl-glucan induced protection against E. coli challenge. Remarkably, Yl-glucan and E. coli interaction increased gene expression of dectin-1 and TLR-2 receptors, signaling pathway Syk/NFκB, and cytokines, such as TNF-α and IL-10. As a consequence of signaling activation, phagocytosis, and nitric oxide production enhanced killing of pathogens. Altogether, Y. lipolytica-glucan demonstrated to possess an immunoprotective potential against E. coli through innate immune response modulation in goat leukocytes.

Recovery from Hypersaline-Stress-Induced Immunity Damage and Intestinal-Microbiota Changes through Dietary β-glucan Supplementation in Nile tilapia (Oreochromis niloticus)

Simple Summary

Long-term hypersaline stress can induce coagulation disorders and splenomegaly and down-regulate the complement pathway in tilapia, which can increase risk in healthy breeding. As a prebiotic, β-glucan dietary supplementation can significantly reduce enlarged spleen resulting from hypersaline stress. The hematological aspects of the red blood cell count, hematocrit, red cell distribution width, platelet count, and plateletcrit were also decreased by supplementation with dietary β-glucan. In the spleen and intestine, β-glucan intake significantly decreased the high expression of immune-related genes due to hypersaline stress resulting from β-glucan intake in tilapia. β-glucan supplementation also significantly increased the abundance of beneficial microbiota such as Lactobacillus, Phycicoccus, and Rikenellaceae in the intestine. In summary, β-glucan intake can relieve tissue damage and optimize the intestinal microbiota of tilapia in brackish water and improve fish health.

Abstract

Long-term exposure to hyperosmotic environments can induce severe immune damage and increase risk in tilapia breeding. As an effective immunoregulator, β-glucan has attracted extensive attention in nutritional research and given rise to high expectations of improving health status and alleviating organismal damage in tilapia, Oreochromis niloticus, in brackish water. In this study, an 8-week cultivation experiment was conducted on tilapia fed a basal diet or diets with β-glucan supplementation in freshwater (control) and brackish water. Growth performance, hematological aspects, immune cytokine expression, and the intestinal microbiota of tilapia were analyzed. The results indicated that supplementation with β-glucan significantly reduced the enlarged spleen of tilapia resulting from hypersaline stress. Tilapia fed β-glucan showed significantly-greater decreases in the red blood cell count, hematocrit, red cell distribution width, platelet count, and plateletcrit than those fed the basal diet. β-glucan significantly decreased the high expression of immune-related genes in the spleen induced by hyperosmotic stress. In the intestine, the high migration inhibitory factor-2 (MIF-2) and IL-1β gene expression induced by hypersaline stress was significantly reduced. β-glucan supplementation also significantly increased the abundance of beneficial microbiota such as Lactobacillus, Phycicoccus, and Rikenellaceae. Therefore, dietary β-glucan supplementation can significantly reduce spleen enlargement and improve immune function in tilapia in brackish water. β-glucan intake can also optimize the intestinal microbiota of tilapia in brackish water and improve fish health.

Removal and Extraction of Carboxylic Acids and Non-ionic Compounds with Simple Hydroxides and Layered Double Hydroxides

Carboxylic acids are an important natural component as a final product or intermediates for syntheses. They are produced in plants, animals and also as products from biotechnological processes. This review presents the use of single hydroxide particles and layered double hydroxides as alternative adsorbents to remove carboxylic acids from liquid media. The proposal to use hydroxide particles is based on its affinity to adsorb or intercalate carboxylic acids. Besides, the change in properties of the adsorbate-sorbate product evinces that this intermediate can be used as a vehicle to transport and release carboxylic acids. Additional examples will also be presented to prove that layered hydroxides are capable of removing non-ionic compounds from wine, milk and tomato. The use of layered compounds to remove active ingredients could reduce the number of separations steps, costs and reduce or eliminate solvents, thus encouraging the design of industrial processes of separation using hydroxides particles.

Chemical and biological protection of food grade nisin through their partial intercalation in laminar hydroxide salts

The use of antimicrobial agents within a matrix, specifically layered compounds, is of growing interest for reducing contamination due to food borne pathogens and deteriorative microorganisms, one of the main health problems worldwide. In this study, zinc layered hydroxide nanoparticles were synthesized as a matrix for nisin immobilization. Layered materials were characterized by X-ray diffraction, Fourier-Transform Infrared and Ultra Violet-Visible spectra, Scanning Electron Microscopy, and by Thermogravimetric Analysis. Thermal, chemical, enzymatic, and biological stabilities were assessed against Lactobacillus brevis as control strain. Free and immobilized nisin in solution were previously subjected to 25 and 121 °C, pH (7, 9) and inactivation with protease before antimicrobial tests that lasted 21 days. Immobilized nisin was found to maintain the activity levels after the protease action while the pure nisin solution lost its activity gradually. Furthermore, immobilized nisin treated at 121 °C and pH 7 showed higher activity than pure nisin after 21 days. These results may support that immobilizing nisin in zinc layered hydroxide salts promoted extended nisin inhibitory activity in solution after thermal, chemical or enzymatic treatments. This research provides an alternative to nisin application that could be used in processes where such operating conditions take place, as in dairy products.

Impact of copper oxide nanoparticles (CuO NPs) exposure on embryo development and expression of genes related to the innate immune system of zebrafish (Danio rerio)

CuO NPs are nanomaterials with catalytic activity and unique thermo-physical properties used in different fields such as sensors, catalysts, surfactants, batteries, antimicrobials and solar energy transformations. Because of its wide field of use, these nanoparticles accumulate in the aquatic environment and thus lead to toxic effects on aquatic organisms. The toxicological findings about CuO NPs are controversial and these effects of CuO NPs on aquatic organisms have not been elucidated in detail. Therefore, the aim of this study was to investigate the toxic effect of CuO NPs on zebrafish embryos using different parameters including molecular and morphologic. For this purpose, zebrafish embryos at 4 h after post fertilization (hpf) were exposed to different concentrations of CuO NPs (0.5, 1, 1.5 mg/L) until 96 hpf. Mortality, hatching, heartbeat, malformation rates were examined during the exposure period. In addition, Raman spectroscopy was used to determine whether CuO NPs entered into the tissues of zebrafish larvae or not. Moreover, the alterations in the expression of genes related to the antioxidant system and innate immune system were examined in the embryos exposed to CuO NPs during 96 h. The results showed that CuO NPs was not able to enter into the zebrafish embryos/larvae tissues but caused an increased the mortality rate, a delayed hatching, and a decreased heartbeat rate. Moreover, CuO NPs caused several types of abnormalities such as head and tail malformations, vertebral deformities, yolk sac edema, and pericardial edema. RT-PCR results showed that the transcription of mtf-1, hsp70, nfkb and il-1β, tlr-4, tlr-22, trf, cebp was changed by the application of CuO NPs. In conclusion, short-term exposure to CuO NPs has toxic effects on the development of zebrafish embryos.

Biosynthesis of β-d-glucan‑gold nanoparticles, cytotoxicity and oxidative stress in mouse splenocytes

This study reports biosynthesis of gold-nanoparticles (AuNPs) by using β-d-glucans isolated from the yeast Yarrowia lypolitica D1. β-d-glucans serve as reducing and stabilizing mediators that induce the formation of AuNPs on the outer surface of the own β-d-glucan. The systems were physicochemically characterized by ultraviolet visible (UV-Vis) spectroscopy, high-resolution transmission electron microscopy (HR-TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and dynamic light scattering (DLS) analyses. The results revealed the generation of AuNPs with quasi-spherical shape or large one dimension (1D) gold-nanostructures (AuNSs) depending on the HAuCl₄ concentration. A cytotoxic study was assessed in mouse splenocytes. Contrary to that expected, important cytotoxicity was found in all β-d-gluc+AuNPs systems by an oxidative stress increase. This study discusses the cytotoxic mechanism, suggesting that the resulting β-d-gluc+AuNPs systems may not be candidates for the formulation of immunostimulants or nanocarriers for biomedical applications.