Seaweed dietary supplements enhance the innate immune response of the mottled rabbitfish, Siganus fuscescens

Synergistic effect of green synthesis magnesium oxide nanoparticles and seaweed extract on improving water quality, health benefits, and disease resistance in Nile tilapia

This study aimed to evaluate the effect of adding liquid extract of algae (Hypnea musciformis, Grateloupia acuminata, and Sargassum muticum) (HGS) and Magnesium oxide nanoparticles (MgO NPs) using this extract to rear water of Oreochromis niloticus, on improving culture water indices, growth performance, digestive enzyme, hemato-biochemical characters, immune, antioxidative responses, and resistance after challenged by Aeromonas hydrophila with specific refer to the potential role of the mixture in vitro as resistance against three strains bacteria (Aeromonas sobria, Pseudomonas fluorescens, P. aeruginosa) and one parasite (Cichlidogyrus tilapia). The first group represented control, HGS0, whereas the other group, HGS5, HGS10, and HGS15 mL-1 of liquid extract, as well as all groups with 7.5 μg mL-1 MgO-NPs added to culture water of O. niloticus, for 60 days. Data showed that increasing levels at HGS 10 and HGS15 mL-1 in to-culture water significantly enhanced growth-stimulating digestive enzyme activity and a significantly improved survival rate of O. niloticus after being challenged with A. hydrophila than in the control group. The total viability, coliform, fecal coliform count, and heavy metal in muscle partially decreased at HGS 10 and HGS15 mL-1 than in the control group. Correspondingly, the highest positive effect on hemato-biochemical indices was noticed at levels HGS 10 and HGS15 mL-1. Fish noticed an improvement in immune and antioxidant indices compared to control groups partially at HGS 10 and HGS15 mL-1. Interestingly, fish cultured in rearing water with the mixture provided downregulated the related inflammatory genes (HSP70, TNF, IL-1β, and IL-8) partially at HGS15 mL-1. In vitro, the mixture showed positive efficiency as an antibacterial and partially antiparasitic at HGS 10 and HGS15 mL-1. This study proposes utilizing a mixture of (HGS) and (MgO-NPs) with optimum levels of 10-15 mL-1 in cultured water to improve water indices, growth, health status, and increased resistance of O. niloticus against bacterial and parasitic infection.

Oral administration of terpenoids and phenol fraction of Padina gymnospora stimulates the nonspecific immune response and expression of immune genes, and protects the common carp (Cyprinus carpio) from experimental Aeromonas hydrophila infection

Common carp (Cyprinus carpio), a valuable aquaculture species susceptible to various infections, requires effective immune enhancement strategies. This study investigates the immunomodulatory effects of orally administered terpenoids and phenol fraction (TPF) from Padina gymnospora in C. carpio, focusing on stimulation of nonspecific immune response, immune gene expression, and protection against experimental infection. P. gymnospora is a brown seaweed species known for its bioactive compounds and medicinal properties. TPF was extracted using the Harborne fractionation method, and the presence of terpenoids and phenol compounds was confirmed by qualitative analysis and high-performance thin layer chromatography (HPTLC). TPF was administered orally in different doses to carp. Nonspecific immune responses were evaluated by measuring cellular ROS, RNI, and peroxidase production. The expression of immune genes (lysozyme and interleukin-1β) was assessed by reverse transcriptase PCR. Furthermore, the protective efficacy of TPF was determined by infecting carp with a virulent pathogen, Aeromonas hydrophila, and monitoring mortality rates and disease symptoms. The results demonstrate that oral TPF administration significantly enhances nonspecific immune responses, with increased ROS, RNI, and peroxidase production, indicating improved immune function. Expression levels of lysozyme and interleukin-1β were upregulated, suggesting immune system activation. Moreover, TPF exhibited significant protection against experimental infection, with lower mortality rates compared to the control group. These findings highlight TPF's potential as an effective immunostimulatory agent, enhancing immune responses and providing infection protection in carp. In conclusion, oral TPF administration stimulates nonspecific immune responses, modulates immune gene expression, and confers protection against experimental infection in carp, displaying its potential for enhancing immune responses and disease resistance in aquaculture species, and contributing to sustainable fish health management.

Antibacterial Activities and Life Cycle Stages of Asparagopsis armata: Implications of the Metabolome and Microbiome

The red alga Asparagopsis armata is a species with a haplodiplophasic life cycle alternating between morphologically distinct stages. The species is known for its various biological activities linked to the production of halogenated compounds, which are described as having several roles for the algae such as the control of epiphytic bacterial communities. Several studies have reported differences in targeted halogenated compounds (using gas chromatography-mass spectrometry analysis (GC-MS)) and antibacterial activities between the tetrasporophyte and the gametophyte stages. To enlarge this picture, we analysed the metabolome (using liquid chromatography-mass spectrometry (LC-MS)), the antibacterial activity and the bacterial communities associated with several stages of the life cycle of A. armata: gametophytes, tetrasporophytes and female gametophytes with developed cystocarps. Our results revealed that the relative abundance of several halogenated molecules including dibromoacetic acid and some more halogenated molecules fluctuated depending on the different stages of the algae. The antibacterial activity of the tetrasporophyte extract was significantly higher than that of the extracts of the other two stages. Several highly halogenated compounds, which discriminate algal stages, were identified as candidate molecules responsible for the observed variation in antibacterial activity. The tetrasporophyte also harboured a significantly higher specific bacterial diversity, which is associated with a different bacterial community composition than the other two stages. This study provides elements that could help in understanding the processes that take place throughout the life cycle of A. armata with different potential energy investments between the development of reproductive elements, the production of halogenated molecules and the dynamics of bacterial communities.

Herbivorous Fish Microbiome Adaptations to Sulfated Dietary Polysaccharides

Marine herbivorous fish that feed primarily on macroalgae, such as those from the genus Kyphosus, are essential for maintaining coral health and abundance on tropical reefs. Here, deep metagenomic sequencing and assembly of gut compartment-specific samples from three sympatric, macroalgivorous Hawaiian kyphosid species have been used to connect host gut microbial taxa with predicted protein functional capacities likely to contribute to efficient macroalgal digestion. Bacterial community compositions, algal dietary sources, and predicted enzyme functionalities were analyzed in parallel for 16 metagenomes spanning the mid- and hindgut digestive regions of wild-caught fishes. Gene colocalization patterns of expanded carbohydrate (CAZy) and sulfatase (SulfAtlas) digestive enzyme families on assembled contigs were used to identify likely polysaccharide utilization locus associations and to visualize potential cooperative networks of extracellularly exported proteins targeting complex sulfated polysaccharides. These insights into the gut microbiota of herbivorous marine fish and their functional capabilities improve our understanding of the enzymes and microorganisms involved in digesting complex macroalgal sulfated polysaccharides. IMPORTANCE This work connects specific uncultured bacterial taxa with distinct polysaccharide digestion capabilities lacking in their marine vertebrate hosts, providing fresh insights into poorly understood processes for deconstructing complex sulfated polysaccharides and potential evolutionary mechanisms for microbial acquisition of expanded macroalgal utilization gene functions. Several thousand new marine-specific candidate enzyme sequences for polysaccharide utilization have been identified. These data provide foundational resources for future investigations into suppression of coral reef macroalgal overgrowth, fish host physiology, the use of macroalgal feedstocks in terrestrial and aquaculture animal feeds, and the bioconversion of macroalgae biomass into value-added commercial fuel and chemical products.

Influence of black rice (Oryza sativa L.) bran derived anthocyanin-extract on growth rate, immunological response, and immune-antioxidant gene expression in Nile tilapia (Oreochromis niloticus) cultivated in a biofloc system

This study investigated the effects of dietary supplementation with anthocyanin extracted from black rice bran (AR) on the growth rate, immunological response, and expression of immune and antioxidant genes in Nile tilapia raised in an indoor biofloc system. A total of 300 Nile tilapia fingerlings (15.14 ± 0.032 g) were maintained in 150 L tanks and acclimatized for two weeks. Five experimental AR diets (0, 1, 2, 4, and 8 g kg^-1) with various anthocyanin doses were used to feed the fish. We observed that the growth and feed utilization of fish fed with different dietary AR levels increased significantly after eight weeks (p < 0.05). In addition, the serum immunity of fish fed AR diets was much greater than that of those fed non-AR diets (p < 0.05). However, there were little or no difference in between fish fed AR enriched diets and the control AR-free diet (p > 0.05). After eight weeks, fish fed AR-supplemented diets had significantly higher mRNA transcript levels in immune (interleukin [IL]-1, IL-8, and liposaccharide-binding protein [LBP]) and antioxidant (glutathione transferase-alpha [GST-α] and glutathione reductase [GSR]) genes compared to control fish fed the AR-free diet, with the greatest enhancement of mRNA transcript levels (in the case of IL-8 by up to about 5.8-fold) in the 4 g kg^-1 AR diet. These findings suggest that dietary inclusion of AR extract from black rice bran at 4-8 g kg^-1 could function as a herbal immunostimulant to enhance growth performance, feed consumption, and immunity in Nile tilapia.

Dietary red macroalgae (Halopithys incurva) improved systemic an mucosal immune and antioxidant parameters and modulated related gene expression in zebrafish (Danio rerio)

In the present study, the effects of dietary Halopithys incurva, a red macroalgae species, (0.25, 0.50, 1%) on whole-body serum and skin mucus immune system, antioxidant system and expression of various genes in zebrafish were investigated. At the end of the 8-week study, total protein, total immunoglobulin and lysozyme activities in whole-body serum and skin mucus increased in fish fed H. incurva (P < 0.05). While an increase was observed in superoxide dismutase (SOD), Catalase (CAT) and glutathione peroxidase (GPx) which are antioxidant enzyme activities in whole-body serum and skin mucus, a decrease in malondialdehyde (MDA) levels was detected (P < 0.05). All of the immune-related genes examined, such as Interleukin-1 beta (IL-1β), Tumor necrosis factor-alpha (TNF-α), Interferon-gamma (INF- γ), were upregulated by the addition of 0.5% H. incurva (P < 0.05). While SOD and GPx, which are antioxidant enzyme-related genes, were remarkably upregulated in macroalgae fed fish (P < 0.05), no change was observed in CAT gene expression (P > 0.05). Based on the results of this study, it is considered that the addition of 0.5% H. incurva to the diets of commercially farmed fish will increase their immune and antioxidant defences and may contribute to the aquaculture sector for more sustainability.

Is the Intestinal Bacterial Community in the Australian Rabbitfish Siganus fuscescens Influenced by Seaweed Supplementation or Geography?

We recently demonstrated that dietary supplementation with seaweed leads to dramatic improvements in immune responses in S. fuscescens, a candidate species for aquaculture development in Asia. Here, to assess whether the immunostimulatory effect was facilitated by changes to the gut microbiome, we investigated the effects of those same seaweed species and four commercial feed supplements currently used in aquaculture on the bacterial communities in the hindgut of the fish. Since we found no correlations between the relative abundance of any particular taxa and the fish enhanced innate immune responses, we hypothesised that S. fuscescens might have a core microbiome that is robust to dietary manipulation. Two recently published studies describing the bacteria within the hindgut of S. fuscescens provided an opportunity to test this hypothesis and to compare our samples to those from geographically distinct populations. We found that, although hindgut bacterial communities were clearly and significantly distinguishable between studies and populations, a substantial proportion (55 of 174 taxa) were consistently detected across all populations. Our data suggest that the importance of gut microbiota to animal health and the extent to which they can be influenced by dietary manipulations might be species-specific or related to an animals’ trophic level.

Potential effects of dietary seaweeds mixture on the growth performance, antioxidant status, immunity response, and resistance of striped catfish (Pangasianodon hypophthalmus) against Aeromonas hydrophila infection

Striped catfish (Pangasianodon hypophthalmus) is one of the important fish species in the world, which is widely cultured in several countries worldwide including Egypt. Aeromonas hydrophila infection showed a high prevalence in the farmed striped catfish negatively affecting its production causing economic loss. Therefore, the finding of functional feed supplements with antimicrobial activity is urgently needed. The use of marine seaweeds as feed supplements has produced satisfactory results as antibacterial agents. Accordingly, the present study was designed to evaluate the dietary effects of seaweeds mixture (Ulva lactuca, Jania rubens, and Pterocladia capillacea) extract (SME) on the growth performance, haemato-chemical parameters, antioxidant capacity, immune indices, and resistance of striped catfish fry against A. hydrophila infection. Four isonitrogenous (30% crude protein) diets were prepared to contain 0.0% (control), 1%, 2%, and 3% SME and were fed to striped catfish fry (1.7 ± 0.1 g) up to apparent satiety three times a day for 60 days. After the feeding trial, fish of each treatment were intraperitoneally injected with a virulent A. hydrophila strain and the relative percentage of survival (RPS) was recorded. The growth-stimulating activity of dietary SME was observed especially at 2% and 3% SME treatments. Similarly, haematological parameters (red blood cells, haemoglobin, haematocrit, and white blood cells) and serum protein profile (total protein, albumin, and globulin) were significantly (P < 0.05) improved, meanwhile serum alanine and aspartate aminotransferases were significantly (P < 0.05) decreased in fish fed with 2 and 3% SME diets. Serum creatinine and uric acid levels revealed no significant (P > 0.05) differences among the experimental groups. Hepatic malondialdehyde and serum nitrous acid levels were significantly decreased; meanwhile hepatic superoxide dismutase, catalase, and glutathione peroxidase levels were significantly increased in all SME-treated groups than the control one. Also, SME supplementations significantly increased the serum lysozyme, total immunoglobulin, and complement C3 activities with highest values at 2% and 3% SME treatments. Interestingly, after bacterial challenge, fish fed SME-supplemented diet were more resistant with the lowest fish mortality (15%) at the 3% SME diet, which exhibit the highest RPS (81.9%). Meanwhile the control group showed highest mortality (85%). According to the regression fitting curve, the current study recommends using the dietary SME with optimum levels of 2.25-2.5% to improve the growth performance, welfare status, and resistance of striped catfish fry against A. hydrophila infection.

Seaweed Aquaculture in Indonesia Contributes to Social and Economic Aspects of Livelihoods and Community Wellbeing

Seaweed farming in Indonesia is carried out throughout much of the archipelago and is mainly undertaken by smallholder farmers. Indonesia is the largest global producer of the red seaweeds Kappaphycus and Eucheuma, which are used to produce carrageenan, and is a major producer of Gracilaria, which is used to produce agar. Seaweed farming is attractive to farmers in rural coastal communities because capital and operating costs are low, farming techniques are not technically demanding, labour requirements are relatively low (allowing farmers to engage in other livelihoods), and production cycles are short (30–45 days), providing regular income. Using reported values for seaweed-farming income, we conclude that seaweed farming can, but does not always, lift rural households above the Indonesian poverty line. In addition to direct financial benefits, seaweed farming also contributes to human and social capital within seaweed farming households and communities. Achieving continued economic and social benefits from seaweed farming will require additional policy development, as well as research and development to support improved and more consistent seaweed productivity and improved product quality at the farm level, provision of effective extension and technical support services, and diversification of the existing value chains in order to reduce the impacts of price fluctuations that are associated with limited global commodity chains.