Properties of Carotenoids in Fish Fitness: A Review

Marine Carotenoids: Unlocking Advanced Antioxidant Mechanisms and Therapeutic Applications for Oxidative Stress

Marine ecosystems are a rich source of bioactive compounds, with carotenoids like astaxanthin, fucoxanthin, and zeaxanthin demonstrating significant antioxidant properties. These carotenoids neutralize reactive oxygen species (ROS), protecting against oxidative damage. This review examines their molecular structures, biosynthesis pathways, and mechanisms of action, including radical scavenging and involvement in key signaling pathways. Antioxidant assays confirm their potent ability to mitigate oxidative stress, with therapeutic implications for chronic diseases such as cancer, cardiovascular disorders, neurodegenerative diseases, and diabetes. Carotenoids also show promise in food, cosmetic, and nutraceutical applications, emphasizing the importance of sustainable sourcing. This review highlights the role of carotenoids in preventive health strategies and their potential to address oxidative stress-related diseases.

Application of Natural Antioxidants as Feed Additives in Aquaculture: A Review

Oxidative stress, a critical factor affecting the health and productivity of aquatic organisms, arises from the imbalance between reactive oxygen species (ROS) production and antioxidant defenses. In aquaculture, natural antioxidants have gained increasing attention as sustainable feed additives to mitigate oxidative damage, enhance immune responses, and improve overall growth performance. This review provides a comprehensive synthesis of the antioxidative mechanisms of key natural antioxidants, including carotenoids, polysaccharides, vitamins, polyphenols, and flavonoids. By neutralizing ROS and modulating cellular signaling pathways such as Nrf2/ARE, these compounds offer significant protective effects against oxidative damage in aquatic species. The manuscript consolidates recent advancements in antioxidant research, highlighting their practical applications in feed formulation and their role in promoting sustainability in aquaculture. This review aims to provide an integrative framework for understanding natural antioxidants' potential, guiding future research and practical implementation in aquaculture systems.

A U-shaped association between composite dietary antioxidant index and migraine in US adults: a nationwide cross-sectional study

BACKGROUND

The field of dietary therapies for migraine has grown in popularity. Less research has been conducted to establish the relationship between migraine and the composite dietary antioxidant index (CDAI), a crucial indicator for evaluating the overall combined effects of multiple dietary antioxidants. Therefore, this study addressed this gap based on the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

Multivariate logistic regression equations were used to investigate the relationship between CDAI and migraine, and smoothed-fitted curves were plotted. After a nonlinear relationship was discovered, the recursive algorithm and a two-stage linear regression model were employed to calculate the turning point. Additional stratified analyses were performed to explore differences between populations.

RESULTS

This study included a total of 9,190 participants aged 20 years old or older. A U-shaped association was observed between the CDAI and migraine, with an inflection point of 0.2. They were negatively correlated before the inflection point with OR of 0.93 (95% CI = 0.88-0.97) and positively correlated after the inflection point with OR of 1.04 (95% CI = 1.01-1.07). This U-shaped relationship persisted among people aged <60 and ≥60 years, women, and people with BMI <30 and ≥30.

CONCLUSIONS

We identified a U-shaped association between CDAI and migraine in the U.S. adult population. Further case-control studies and experimental research are needed to explore the underlying mechanisms of action.

Natural-based solutions to mitigate dietary microplastics side effects in fish

Dietary microplastics (MPs) can be consumed by fish, crossing through the gastrointestinal tract. MPs smaller than 20 μm can easily translocate to other organs, such as liver, commonly triggering oxidative stress in fish. Given the current unlikelihood of their short-term elimination, strategies to mitigate MPs-related issues on fish are of considerable interest to the scientific community. In the present study, to reduce both the dietary MPs-induced oxidative stress and the accumulation of MPs, the effectiveness of microencapsulated astaxanthin (ASX) was evaluated in zebrafish (Danio rerio). Specifically, zebrafish were reared from larvae to adults (6 months) and fed diets containing MPs different in range-size (polymer A: 1-5 μm; polymer B: 40-47 μm) at different concentrations (50 or 500 mg/kg). After this period, fish from each experimental group were divided in two sub-groups that were fed, for an additional month, with the previous diets or with the same diets containing implemented with microencapsulated ASX (7 g/kg), respectively. Results showed that microencapsulated ASX was able to counteract the negative effects caused by MPs different in size. Particularly, in zebrafish fed diets containing polymer B microbeads, microencapsulated astaxanthin was able to restore the intestinal epithelium, affected by the abrasive role of MPs during gut transit. Differently, in zebrafish fed diets containing polymer A microbeads, absorbed at intestinal level and translocated mainly to the liver, the microencapsulated ASX decreased the oxidative stress response and reduced the MPs accumulation in target organs due to the antioxidant and the coagulant properties of the ASX and microcapsules wall, respectively. Taken together, the results highlighted that the aquafeeds' implementation with microencapsulated astaxanthin is a prospective tool to prevent MPs-related issues in fish.

Genome-wide association identifies genomic regions influencing fillet color in Northwest Atlantic salmon (Salmo salar Linnaeus 1758)

Atlantic salmon (Salmo salar) is an important source of food globally; however, fillet color can significantly affect consumer purchasing, leading to potential food waste. Fish diets can be supplemented with astaxanthin to increase the organic pigment, carotenoid, responsible for flesh coloration; however, there is variation in the amount of overall fillet coloration in response to feeding astaxanthin. The uptake of this pigment is influenced by the environment and genetics and has been shown to be heritable. Therefore, we set out to determine the genomic associations of two separate year classes of farmed North American Atlantic salmon with measured Minolta Chroma Meter (lightness, redness, and yellowness) and SalmoFan phenotypic traits. Using ASReml-R genome-wide association, two genetic markers on chromosome 26 were significantly associated with almost all color traits, and these two markers explained between 6.0% and 12.5% of the variances. The genomic region on chromosome 26 was importantly found to be associated with the beta-carotene oxygenase 1 (bco1) gene, which is essential in the conversion of beta-carotenoids to vitamin A, implying that this gene may also play an important role in flesh coloration in North American Atlantic salmon. Additionally, there were several genomic regions significantly associated with color traits, in which the accompanying genes had functions in line with thermogenesis, immune function, and pathogenic responses. Understanding how environmental and genetic factors work together to affect fillet quality traits will help inform genetic improvement.

Ketocarotenoids adonirubin and adonixanthin: Properties, health benefits, current technologies, and emerging challenges

Given their multifaceted roles, carotenoids have garnered significant scientific interest, resulting in a comprehensive and intricate body of literature that occasionally presents conflicting findings concerning the proper characterization, quantification, and bioavailability of these compounds. Nevertheless, it is undeniable that the pursuit of novel carotenoids remains a crucial endeavor, as their diverse properties, functionalities and potential health benefits make them invaluable natural resources in agri-food and health promotion through the diet. In this framework, particular attention is given to ketocarotenoids, viz., astaxanthin (one of them) stands out for its possible multifunctional role as an antioxidant, anticancer, and antimicrobial agent. It has been widely explored in the market and utilized in different applications such as nutraceuticals, food additives, among others. Adonirubin and adonixanthin can be naturally found in plants and microorganisms. Due to the increasing significance of natural-based products and the remarkable opportunity to introduce these ketocarotenoids to the market, this review aims to provide an expert overview of the pros and cons associated with adonirubin and adonixanthin.

Impacts of astaxanthin-enriched Paracoccus carotinifaciens on growth, immune responses, and reproduction performance of broodstock Nile tilapia during winter season

The growth, immune response, and reproductive performance of broodstock of Nile tilapia (Oreochromis niloticus) under winter stress conditions were investigated the effects of supplementary diets with astaxanthin-enriched Paracoccus carotinifaciens. Throughout an eight-week period in the winter season, male and female tilapia were fed with diets containing different levels of P. carotinifaciens dietary supplementation: 0 g/kg (T1; control), 5 g/kg (T2), 10 g/kg (T3), and 20 g/kg (T4). Subsequently, a four-week mating system was implemented during the winter stress period. The results revealed that there were no significant differences observed in growth, hematological indices, and blood chemical profiles among all treatment groups for both male and female tilapia. However, a significant increase in cholesterol content was noted in both male and female tilapia fed with the T4 diet (p<0.05). The total carotenoid content in the muscle was evaluated, and significantly higher values were found in both male and female tilapia that fed T4 supplementation (p<0.05). Moreover, immunological parameters such as myeloperoxidase and antioxidant parameters in the liver including superoxide dismutase activity and catalase enzyme activity showed significant increases in tilapia fed with the T4 diet. The impact of P. carotinifaciens supplementation on broodstock tilapia indicated a significant increase in spermatozoa concentration in males and increased egg production in females after consumption of the T4 diet (p<0.05). Thus, this study highlighted that the presence of astaxanthin-enriched P. carotinifaciens in the diet of broodstock Nile tilapia can lead to the accumulation of carotenoids in their muscle tissue, improvement in antioxidant status, enhancement of immune function, and potential enhancement of reproductive capabilities, even under overwintering conditions.

Novel protective aspects of dietary polyphenols against pesticidal toxicity and its prospective application in rice-fish mode: A Review

The rice fish system represents an innovative and sustainable approach to integrated farming, combining rice cultivation with fish rearing in the same ecosystem. However, one of the major challenges in this system is the pesticidal pollution resulting from various sources, which poses risks to fish health and overall ecosystem balance. In recent years, dietary polyphenols have emerged as promising bioactive compounds with potential chemo-preventive and therapeutic properties. These polyphenols, derived from various plant sources, have shown great potential in reducing the toxicity of pesticides and improving the health of fish within the rice fish system. This review aims to explore the novel aspects of using dietary polyphenols to mitigate pesticidal toxicity and enhance fish health in the rice fish system. It provides comprehensive insights into the mechanisms of action of dietary polyphenols and their beneficial effects on fish health, including antioxidant, anti-inflammatory, and detoxification properties. Furthermore, the review discusses the potential application methods of dietary polyphenols, such as direct supplementation in fish diets or through incorporation into the rice fields. By understanding the interplay between dietary polyphenols and pesticides in the rice fish system, researchers can develop innovative and sustainable strategies to promote fish health, minimize pesticide impacts, and ensure the long-term viability of this integrated farming approach. The information presented in this review will be valuable for scientists, aqua-culturists, and policymakers aiming to implement eco-friendly and health-enhancing practices in the rice fish system.

Recent progress in practical applications of a potential carotenoid astaxanthin in aquaculture industry: a review

Astaxanthin is the main natural C40 carotenoid used worldwide in the aquaculture industry. It normally occurs in red yeast Phaffia rhodozyma and green alga Haematococcus pluvialis and a variety of aquatic sea creatures, such as trout, salmon, and shrimp. Numerous biological functions reported its antioxidant and anti-inflammatory activities since astaxanthin possesses the highest oxygen radical absorbance capacity (ORAC) and is considered to be over 500 more times effective than vitamin E and other carotenoids such as lutein and lycopene. Thus, synthetic and natural sources of astaxanthin have a commanding influence on industry trends, causing a wave in the world nutraceutical market of the encapsulated product. In vitro and in vivo studies have associated astaxanthin's unique molecular features with various health benefits, including immunomodulatory, photoprotective, and antioxidant properties, providing its chemotherapeutic potential for improving stress tolerance, disease resistance, growth performance, survival, and improved egg quality in farmed fish and crustaceans without exhibiting any cytotoxic effects. Moreover, the most evident effect is the pigmentation merit, where astaxanthin is supplemented in formulated diets to ameliorate the variegation of aquatic species and eventually product quality. Hence, carotenoid astaxanthin could be used as a curative supplement for farmed fish, since it is regarded as an ecologically friendly functional feed additive in the aquaculture industry. In this review, the currently available scientific literature regarding the most significant benefits of astaxanthin is discussed, with a particular focus on potential mechanisms of action responsible for its biological activities.

Effect of dietary intervention with Capsicum annuum extract on growth performance, physiological status, innate immune response, and related gene expression in Nile tilapia

The red pepper (Capsicum annuum) has gained great attention recently because of its biological and pharmacological characteristics. The present approach aimed to evaluate the effects of C. annuum alcoholic extract (CAE) supplementation on Nile tilapia (Oreochromis niloticus) growth performance, physiological status, some metabolic, immune, and regulatory genes expression, and resistance against Streptococcus agalactiae infection. Fish (22.26 ± 0.19 g) were assigned to four treatments (five replicates, each with 10 fish replicate-1) and fed tested diets for 60 days. The experimental diets were supplemented with CAE at 0, 0.4, 0.8, and 1.6 g kg-1, expressed as CAE0, CAE0.4, CAE0.8, and CAE1.6, respectively. The findings exhibited that CAE dietary supplementation improved growth performance, feed utilization, elevated growth hormone level, and digestive enzyme activities (amylase and protease), and lowered leptin hormone in a level-dependent manner. Boosting the mRNA expression of the transporter proteins (solute carrier family 15 member 2 and solute carrier family 26 member 6) and insulin-like growth factor-1 genes with a decrease in the myostatin gene expression was noticed in the CAE-fed groups. The innate immune (serum bactericidal activity %, complement 3, and phagocytic activity %) and antioxidant (glutathione peroxidase and total antioxidant capacity) parameters were significantly (p < 0.05) improved, and the serum malondialdehyde level was significantly decreased by CAE dietary inclusion. A marked upregulation in the mRNA expression of interleukins (il-1β, il-6, il-8, and il-10), transforming growth factor-β, glutathione peroxidase, and glutathione synthetase genes were observed in CAE-fed groups. Dietary CAE decreased the cumulative mortalities after the challenge with S. agalactiae by 20, 13.33, and 10% in CAE0.4, CAE0.8, and CAE1.6, respectively, compared to the control (40%). Overall, dietary supplementation with CAE could improve growth performance and physiological status, and modulate the expression of several regulatory genes in Nile tilapia. The recommended level of CAE is 1.6 g kg-1 to augment growth and health status.

Astaxanthin from microalgae: A review on structure, biosynthesis, production strategies and application

Astaxanthin is a red-colored secondary metabolite with excellent antioxidant properties, typically finds application as foods, feed, cosmetics, nutraceuticals, and medications. Astaxanthin is usually produced synthetically using chemicals and costs less as compared to the natural astaxanthin obtained from fish, shrimps, and microorganisms. Over the decades, astaxanthin has been naturally synthesized from Haematococcus pluvialis in commercial scales and remains exceptional, attributed to its higher bioactive properties as compared to synthetic astaxanthin. However, the production cost of algal astaxanthin is still high due to several bottlenecks prevailing in the upstream and downstream processes. To that end, the present study intends to review the recent trends and advancements in astaxanthin production from microalgae. The structure of astaxanthin, sources, production strategies of microalgal astaxanthin, and factors influencing the synthesis of microalgal astaxanthin were discussed while detailing the pathway involved in astaxanthin biosynthesis. The study also discusses the relevant downstream process used in commercial scales and details the applications of astaxanthin in various health related issues.

Triphenyltin Influenced Carotenoid-Based Coloration in Coral Reef Fish, Amphiprion ocellaris, by Disrupting Carotenoid Metabolism

Triphenyltin (TPT), a kind of persistent pollutant, is prevalent in the aquatic environment and could pose a threat to coral reef fish. However, little is known about the toxicity of TPT on coral reef fish, especially regarding the representative characteristics of body coloration. Therefore, this study chose the clownfish (Amphiprion ocellaris) in order to investigate the effects of TPT exposure on its carotenoid-based body coloration under the environmentally relevant concentrations (0, 1, 10 and 100 ng/L). After TPT exposure for 60 d, the carotenoid contents were decreased and histological damage in the liver was found, shown as nuclear pyknosis and shift, lipid deposition and fibrotic tissue hyperplasia. Liver transcriptomic analysis showed that TPT exposure interfered with oxidative phosphorylation and fatty acid metabolism pathways, which related to carotenoids uptake and metabolism. Furthermore, TPT exposure led to oxidative damage in the liver, which is responsible for the changes in the antioxidant capacity of enzymes, including GSH, MDA, POD, CAT and T-SOD. TPT exposure also affected the genes (Scarb1, CD36, Stard3 and Stard5) related to carotenoid absorption and transport, as well as the genes (GstP1 and Bco2) related to carotenoid deposition and decomposition. Taken together, our results demonstrate that TPT influenced carotenoid-based coloration in coral reef fish by disrupting carotenoid metabolism, which complements the ecotoxicological effects and toxic mechanisms of TPT and provides data for the body color biology of coral reef fishes.

All Kinds of Sunny Colors Synthesized from Methane: Genome-Encoded Carotenoid Production by Methylomonas Species

Carotenoids are secondary metabolites that exhibit antioxidant properties and are characterized by a striking range of colorations from red to yellow. These natural pigments are synthesized by a wide range of eukaryotic and prokaryotic organisms. Among the latter, carotenoid-producing methanotrophic bacteria, which display fast growth on methane or natural gas, are of particular interest as potential producers of a feed protein enriched with carotenoids. Until recently, Methylomonas strain 16a and Methylomonas sp. ZR1 remained the only representatives of the genus for which detailed carotenoid profile was determined. In this study, we analyzed the genome sequences of five strains of Methylomonas species whose pigmentation varied from white and yellow to orange and red, and identified carotenoids produced by these bacteria. Carotenoids synthesized using four pigmented strains included C30 fraction, primarily composed of 4,4'-diaplycopene-4,4'-dioic acid and 4,4'-diaplycopenoic acid, as well as C40 fraction with the major compound represented by 1,1'-dihydroxy-3,4-didehydrolycopene. The genomes of studied Methylomonas strains varied in size between 4.59 and 5.45 Mb and contained 4201-4735 protein-coding genes. These genomes and 35 reference Methylomonas genomes available in the GenBank were examined for the presence of genes encoding carotenoid biosynthesis. Genomes of all pigmented Methylomonas strains harbored genes necessary for the synthesis of 4,4'-diaplycopene-4,4'-dioic acid. Non-pigmented "Methylomonas montana" MW1T lacked the crtN gene required for carotenoid production. Nearly all strains possessed phytoene desaturases, which explained their ability to naturally synthesize lycopene. Thus, members of the genus Methylomonas can potentially be considered as producers of C30 and C40 carotenoids from methane.

Captivating Colors, Crucial Roles: Astaxanthin's Antioxidant Impact on Fish Oxidative Stress and Reproductive Performance

Fish, constantly exposed to environmental stressors due to their aquatic habitat and high metabolic rates, are susceptible to oxidative stress. This review examines the interplay between oxidative stress and fish reproduction, emphasizing the potent antioxidant properties of astaxanthin. Our primary objective is to highlight astaxanthin's role in mitigating oxidative stress during critical reproductive stages, leading to improved gamete quality, ovary development, and hormone levels. We also explore its practical applications in aquaculture, including enhanced pigmentation and overall fish health. We conducted a comprehensive literature review, analyzing studies on astaxanthin's antioxidant properties and its impact on fish reproduction. Astaxanthin, a carotenoid pigment, effectively combats reactive oxygen species, inhibiting lipid peroxidation and maintaining membrane integrity. It significantly enhances reproductive success in fish and improves overall fish health in aquaculture settings. This review reveals astaxanthin's multifaceted benefits in fish health and reproduction, offering economic advantages in aquaculture. Future research should delve into species-specific responses, optimal dosages, and the long-term effects of astaxanthin supplementation to inform sustainable aquaculture strategies.

Effects of Red Yeast (Sporidiobolus pararoseus) on Growth, Innate Immunity, Expression of Immune-related Genes and Disease Resistance of Nile Tilapia (Oreochromis niloticus)

The purpose of this study was to evaluate the effects of red yeast (Sporidiobolus pararoseus) produced from crude glycerol, as a by-product of the biodiesel production process, on the growth, innate immunity, expression of immune-related gene, and resistance of Nile tilapia against challenge with Streptococcus agalactiae. Fish were fed diets supplied with different concentrations of S. pararoseus dried cells at 0.0 (control; T1), 5.0 (T2), 10.0 (T3), and 20.0 (T4) g kg-1 diets for 90 days. The results showed that final body weight, weight gain, and average daily gain were significantly higher in fish fed T3 and T4 compared to the control group (p < 0.05). Likewise, significant (p < 0.05) increases in total carotenoid content, liver superoxide dismutase activity (SOD), and serum lysozyme and albumin were observed in Nile tilapia fed S. pararoseus, with the highest (p < 0.05) values displayed in fish fed the T4 diet. Moreover, up-regulation of IL-1β transcription in Nile tilapia spleen and liver was observed in fish feeding group T4. In a challenge test against S. agalactiae, the fish survival rate was significantly higher in fish fed red yeast compared to the control group (p < 0.05). The highest bactericidal activity found in the T4 group (p < 0.05). However, no significant differences were found in hematology, blood chemical, malondialdehyde (MDA), body chemical composition, organosomatic indices, and myeloperoxidase (p > 0.05) in all treatments. The present results suggested that red yeast S. pararoseus (20.0 g kg-1) can be used as a potential supplementation on growth, immune response, and disease resistance of Nile tilapia.

RNA-Seq analysis of the pyloric caecum, liver, and muscle reveals molecular mechanisms regulating fillet color in rainbow trout

BACKGROUND

The characteristic pink-reddish color in the salmonids fillet is an important, appealing quality trait for consumers and producers. The color results from diet supplementation with carotenoids, which accounts for up to 20-30% of the feed cost. Pigment retention in the muscle is a highly variable phenotype. In this study, we aimed to understand the molecular basis for the variation in fillet color when rainbow trout (Oncorhynchus mykiss) fish families were fed an Astaxanthin-supplemented diet. We used RNA-Seq to study the transcriptome profile in the pyloric caecum, liver, and muscle from fish families with pink-reddish fillet coloration (red) versus those with lighter pale coloration (white).

RESULTS

More DEGs were identified in the muscle (5,148) and liver (3,180) than in the pyloric caecum (272). Genes involved in lipid/carotenoid metabolism and transport, ribosomal activities, mitochondrial functions, and stress homeostasis were uniquely enriched in the muscle and liver. For instance, the two beta carotene genes (BCO1 and BCO2) were significantly under-represented in the muscle of the red fillet group favoring more carotenoid retention. Enriched genes in the pyloric caecum were involved in intestinal absorption and transport of carotenoids and lipids. In addition, the analysis revealed the modulation of several genes with immune functions in the pyloric caecum, liver, and muscle.

CONCLUSION

The results from this study deepen our understanding of carotenoid dynamics in rainbow trout and can guide us on strategies to improve Astaxanthin retention in the rainbow trout fillet.

Identification and Characterization of a Novel Microalgal Strain from the Antofagasta Coast Tetraselmis marina AC16-MESO (Chlorophyta) for Biotechnological Applications

The wide rocky coastline of the Antofagasta hosts an intertidal ecosystem in which the species that inhabit it are routinely exposed to a wide range of physical and chemical conditions and have therefore evolved to tolerate extremes. In the search for new species of potential biotechnological interest with adaptations to a wide range of environmental conditions, the isolation and characterization of microalgae from these ecosystems is of great interest. Here, a new microalgal strain, Tetraselmis marina AC16-MESO, is described, which was isolated from a biofilm collected on the intertidal rocks of the Antofagasta coast (23°36'57.2″ S, 70°23'33.8″ W). In addition to the morphological characterization, 18S and ITS sequence as well as ITS-2 secondary structure analysis revealed an identity of 99.76% and 100% with the species Tetraselmis marina, respectively. The analyses of the culture characteristics and biochemical content showed similarities with other strains that are frequently used in aquaculture, such as the species Tetraselmis suecica. In addition, it is tolerant of a wide range of salinities, thus allowing its culture in water of varying quality. On the other hand, added to these characteristics, the results of the improvement of the lipid content in stressful situations of salinity observed in this study, together with other antecedents such as the potential in bioremediation already published for this strain by the same research group, present a clear example of its biotechnological plasticity. It is noteworthy that this strain, due to its characteristics, allows easy collection of its biomass by decantation and, therefore, a more cost-efficient harvesting than for other microalgal strains. Therefore, this new strain of Tetraselmis marina, first report of this species in Chile, and its morphologically, molecularly and biochemically description, presents promising characteristics for its use in biotechnology and as feed for aquaculture.

Effect of dietary inclusion of microalgae (Nannochloropsis gaditana and Schizochytrium spp) on non-specific immunity and erythrocyte maturity in Atlantic salmon fingerlings

The parr-smolt transformation in salmonids involves a critical period characterized by systemic changes associated with the fish's immune response. In this context, as a dietary ingredient in functional diets, microalgae offer an alternative due to their nutritional and bioactive compounds that could strengthen the immune status. This study evaluated the effect of a diet supplemented with Schizochytrium spp and Nannochloropsis gaditana on the expression of genes associated with the antibacterial response. Additionally, the study assessed the effect on the leukocyte population and erythrocyte maturity in Salmo salar blood. Fish were fed for 30 days with a microalgal mixture (1:1) at a 10% inclusion. Each diet was randomly assigned to a tank using a completely randomized design (CRD) with four replications. Each tank was stocked with 70 Atlantic salmon fingerlings with an initial mean weight of 78.87 ± 0.84. Transcription levels were quantified and analyzed by qRT-PCR from cell isolates and mucus tissue. Furthermore, cell count and identification of leukocytes and classification of cellular maturity of erythrocytes using a neural network with a multilayer perceptron (MLP) were performed. Our results showed a significant (p < 0.05) increase in fold change expression of C3 (2.54 ± 0.65) and NK-Lysine (6.84 ± 0.94) in erythrocytes of microalgae-supplemented fish. Moreover, a significant increase of 1.59 and 2.35 times in monocytes and immature erythrocytes, respectively, was observed in the same group of fish (p < 0.05). This study's results indicate that dual microalgae (Schizochytrium spp and N. gaditana) supplementation can increase innate humoral antibacterial components, particularly in erythrocyte tissue, and increase phagocytic cells and immature erythrocytes in S. salar blood.

Comprehensive Comparison of Effects of Antioxidant (Astaxanthin) Supplementation from Different Sources in Haliotis discus hannai Diet

Dietary antioxidant supplementation, especially astaxanthin, has shown great results on reproductive aspects, egg quality, growth, survival, immunity, stress tolerance, and disease resistance in aquatic animals. However, the effects of dietary astaxanthin supplementation from different sources are still unknown. A comprehensive comparison of survival, growth, immune response, antioxidant activity, thermal resistance, disease resistance, and intestinal microbial structure was conducted in dietary antioxidant supplementation from the sources of Gracilaria lemaneiformis (GL), industrial synthetic astaxanthin (80 mg/kg astaxanthin actual weight, named as group 'SA80'), Phaffia rhodozyma (80 mg/kg astaxanthin actual weight, named as group 'PR80') and Haematococcus pluvialis (120 mg/kg astaxanthin actual weight, named as group 'HP120') at their optimal supplementation amounts. Furthermore, the SA80, PR80, and HP120 groups performed better in all aspects, including survival, growth, immune response, antioxidant activity, thermal resistance, and disease resistance, compared with the GL group. The PR80 and HP120 group also had a better growth performance than the SA80 group. In terms of heat stress and bacterial challenge, abalone in the PR80 group showed the strongest resistance. Overall, 80 mg/kg astaxanthin supplementation from Phaffia rhodozyma was recommended to obtain a more effective and comprehensive outcome. This study contributes to the discovery of the optimum dietary astaxanthin supplementation source for abalone, which is helpful to improve the production efficiency and economic benefits of abalone. Future research can further explore the action mechanism and the method of application of astaxanthin to better exploit its antioxidant role.

Dietary Fruit By-Products Improve the Physiological Status of Nile Tilapias (Oreochromis niloticus) and the Quality of Their Meat

By-products from fruit industrialization retain nutritional and functional components; thus, they may find use in animal feeding. This study aimed to assess the effects of dietary fruit industrial by-products on the tilapias blood biochemical and oxidative parameters and on the composition and lipid peroxidation of their fillets. Four diets were supplied to the tilapias: a C-control diet, with no fruit meal, and three diets containing 5% of either acerola (ACM), apple (APM) or grape (GRM) meal. The phenolic compounds and the carotenoids in the meals and their antioxidant capacities were measured. Fish were weighed and measured for the calculation of the growth performance data, their blood was analyzed for health and oxidative status biomarkers and their fillets were analyzed for proximal composition and lipid peroxidation. Grape meal had the highest concentration of phenolics and carotenoids and the highest antioxidant activity, followed by acerola and apple meals. The productive performance was similar among the treatments. The fruit by-product diets either maintained or improved the biochemical biomarkers of health and improved the oxidative status of the fish. The fruit by-product diets increased the concentration of lipids in the fillets and slowed down the onset of the lipid peroxidation during frozen storage.

Metabolic Engineering of Model Microorganisms for the Production of Xanthophyll

Xanthophyll is an oxidated version of carotenoid. It presents significant value to the pharmaceutical, food, and cosmetic industries due to its specific antioxidant activity and variety of colors. Chemical processing and conventional extraction from natural organisms are still the main sources of xanthophyll. However, the current industrial production model can no longer meet the demand for human health care, reducing petrochemical energy consumption and green sustainable development. With the swift development of genetic metabolic engineering, xanthophyll synthesis by the metabolic engineering of model microorganisms shows great application potential. At present, compared to carotenes such as lycopene and β-carotene, xanthophyll has a relatively low production in engineering microorganisms due to its stronger inherent antioxidation, relatively high polarity, and longer metabolic pathway. This review comprehensively summarized the progress in xanthophyll synthesis by the metabolic engineering of model microorganisms, described strategies to improve xanthophyll production in detail, and proposed the current challenges and future efforts needed to build commercialized xanthophyll-producing microorganisms.

Spirulina-enriched Substrate to Rear Black Soldier Fly (Hermetia illucens) Prepupae as Alternative Aquafeed Ingredient for Rainbow Trout (Oncorhynchus mykiss) Diets: Possible Effects on Zootechnical Performances, Gut and Liver Health Status, and Fillet Quality

In the present study, an organic substrate (coffee silverskin) enriched with spirulina (Arthrospira platensis; 15% w/w), as a source of lipids and bioactive molecules, was used to rear the black soldier fly (Hermetia illucens) prepupae. Three grossly isonitrogenous, isoproteic, isolipidic and isoenergetic experimental diets for rainbow trout (Oncorhynchus mykiss) juveniles were then produced: a control diet (HM0) mostly including fish meal and fish oil, and two other test diets named HM3 and HM20, in which 3 or 20% of the marine ingredients were substituted with full fat black soldier fly prepupae meal (HM), respectively. Experimental diets were provided for 6 weeks, and at the end of the trial the physiological responses and marketable traits of the fish were investigated using a multidisciplinary approach. Generally, all test diets were well accepted, and fish growth, gut and liver health status, and marketable characteristics were not impaired by the experimental diets. However, an increased immuno-related gene expression along with a slight reduction of fillet redness and yellowness was evident in fish from the HM20 group.

An extensive review of marine pigments: sources, biotechnological applications, and sustainability

The global demand for food and healthcare products based on natural compounds means that the industrial and scientific sectors are on a continuous search for natural colored compounds that can contribute to the replacement of synthetic colors. Natural pigments are a heterogeneous group of chemical molecules, widely distributed in nature. Recently, the interest in marine organisms has increased as they represent the most varied environment in the world and provide a wide range of colored compounds with bioactive properties and biotechnological applications in areas such as the food, pharmaceutical, cosmetic, and textile industries. The use of marine-derived pigments has increased during the last two decades because they are environmentally safe and healthy compounds. This article provides a comprehensive review of the current knowledge of sources, applications, and sustainability of the most important marine pigments. In addition, alternatives to protect these compounds from environmental conditions and their applications in the industrial sector are reviewed.

4,4'-Diaponeurosporene Production as C30 Carotenoid with Antioxidant Activity in Recombinant Escherichia coli

Carotenoids, a group of isoprenoid pigments, are naturally synthesized by various microorganisms and plants, and are industrially used as ingredients in food, cosmetic, and pharmaceutical product formulations. Although several types of carotenoids and diverse microbial carotenoid producers have been reported, studies on lactic acid bacteria (LAB)-derived carotenoids are relatively insufficient. There is a notable lack of research focusing on C₃₀ carotenoids, the functional characterizations of their biosynthetic genes and their mass production by genetically engineered microorganisms. In this study, the biosynthesis of 4,4'-diaponeurosporene in Escherichia coli harboring the core biosynthetic genes, dehydrosqualene synthase (crtM) and dehydrosqualene desaturase (crtN), from Lactiplantibacillus plantarum subsp. plantarum KCCP11226 was constructed to evaluate and enhance 4,4'-diaponeurosporene production and antioxidant activity. The production of 4,4'-diapophytoene, a substrate of 4,4'-diaponeurosporene, was confirmed in E. coli expressing only the crtM gene. In addition, recombinant E. coli carrying both C₃₀ carotenoid biosynthesis genes (crtM and crtN) was confirmed to biosynthesize 4,4'-diaponeurosporene and exhibited a 6.1-fold increase in carotenoid production compared to the wild type and had a significantly higher antioxidant activity compared to synthetic antioxidant, butylated hydroxytoluene. This study presents the discovery of an important novel E. coli platform in consideration of the industrial applicability of carotenoids.

Bioactive immunostimulants as health-promoting feed additives in aquaculture: A review

Bioactive immunostimulants could be derived from different sources like plants, animals, microbes, algae, yeast, etc. Bioactive immunostimulants are the most significant role to enhance aquatic production, as well as the cost of this method, which is effective, non-toxic, and environment-friendly. These immunostimulants are supportive to increase the immune system, growth, antioxidant, anti-inflammatory, and disease resistance of aquatic animals' health and also improve aquatic animal feed. Diseases are mainly targeted to the immune system of aquatic organisms in such a way that different processes of bioactive immunostimulants progress are considered imperative techniques for the development of aquaculture production. Communicable infections are the main problem for aquaculture, while the mortality and morbidity connected with some outbreaks significantly limit the productivity of some sectors. Aquaculture is considered the mainly developing food production sector globally. Protein insists is an important issue in human nutrition. Aquaculture has been an exercise for thousands of years, and it has now surpassed capture fisheries as the most vital source of seafood in the world. Limited study reports are available to focal point on bioactive immunostimulants in aquaculture applications. This review report provides information on the nutritional administration of bioactive immunostimulants, their types, functions, and beneficial impacts on aquatic animals' health as well as for the feed quality development in the aquaculture industry. The scope of this review combined to afford various kinds of natural derived bioactive molecules utilization and their beneficial effects in aquaculture applications.

Isolation, Identification, and Function of Rhodotorula mucilaginosa TZR2014 and Its Effects on the Growth and Health of Weaned Piglets

A red yeast isolated from orange and grape soil and identified by the 26S rDNA sequence analysis revealed that it was Rhodotorula mucilaginosa and named TZR₂₀₁₄. Its biomass and carotenoid production reached a maximum when using the fermentation medium with pH 6.0, containing 5% glucose, 1% peptone, and 1.5% yeast powder. TZR₂₀₁₄ was resistant to 55°C for 15 min, 0.2% pig bile salts for 4 h, and artificial gastric and intestinal fluids. A total of thirty 28-day weaned pigs were divided into three groups, and the piglets were fed a basal diet (CON), a basal diet and orally administered 1 ml 1.0 × 10¹⁰ CFU/ml Candida utilis DSM 2361 three times (C. utilis), or a basal diet and orally administered 1 ml 1.0 × 10¹⁰ CFU/mL TZR₂₀₁₄ three times daily (R. mucilaginosa) for 4 weeks. Compared with the piglets in the CON group, those in the C. utilis or R. mucilaginosa group reported an increased average daily weight gain and average daily feed intake (P < 0.05) and a decreased feed/gain (P < 0.05). The diarrhea rate of piglets in the R. mucilaginosa group was lower than that in the CON and C. utilis groups (P < 0.05). Compared with that in the CON and C. utilis groups, the R. mucilaginosa group reported an increased ileum villus height (P < 0.05), serum concentration of total antioxidant content, total superoxide dismutase, and glutathione peroxidase and pepsin and lipase activities in the intestinal content, while it reported a decreased serum concentration of malondialdehyde and pH of the intestinal tract (P < 0.05). The relative abundances of Proteobacteria and Megasphaera of caecum in the R. mucilaginosa group were lower than those in the CON and C. utilis groups (P < 0.05). The relative abundances of Prevotella, Ruminococcaceae, Succinivibrio, Rikenellaceae RC9 gut group, and Roseburia of caecum in the R. mucilaginosa group were higher than those in the CON and C. utilis groups (P < 0.05). R. mucilaginosa TZR₂₀₁₄ can produce carotenoids and adapts to the animal's gastrointestinal environment. Oral R. mucilaginosa TZR₂₀₁₄ improved growth performance, enhanced antioxidant capacity, strengthened gastrointestinal digestion, and maintained the intestinal microbiological balance of piglets.

Exploring the Biotechnological Value of Marine Invertebrates: A Closer Look at the Biochemical and Antioxidant Properties of Sabella spallanzanii and Microcosmus squamiger

Sabella spallanzanii and Microcosmus squamiger were profiled for proximate composition, minerals, amino acids, fatty acids (FA), carotenoids, radical scavenging activity on the 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC) and iron and copper chelating properties. Microcosmus squamiger had the highest level of moisture and crude protein, S. spallanzanii was enriched in crude fat and ash. Both species had similar levels of carbohydrates and energy. There was a prevalence of arginine and glycine in S. spallanzanii, and of taurine in M. squamiger. The most abundant minerals in both species were Na, Ca, and K. The methanol extract of S. spallanzanii had metal chelating properties towards copper and iron, while the methanol extract of M. squamiger was able to chelate copper. M. squamiger extracts had similar ORAC values. Fucoxanthinol and fucoxanthin were the major carotenoids in the M. squamiger dichloromethane extract. Saturated FA were more abundant than unsaturated ones in methanol extracts, and unsaturated FA prevailed in the dichloromethane extracts. Palmitic acid was the predominant FA in methanol extracts, whereas eicosapentaenoic (EPA) and dihomo-γ-linolenic acids were the major compounds in dichloromethane extracts. Low n-6/n-3 ratios were obtained. Our results suggests that both species could be explored as sources of bioactive ingredients with multiple applications.