Seaweeds as an alternative therapeutic source for aquatic disease management

Phytochemical screening and antibacterial assessment of two macroalgae Ulva papenfussi and Ulva nematoidea (Chlorophyta) against the bacterium Vibrio parahaemolyticus

This study was conducted to determine whether the macroalgae Ulva papenfussi and Ulva nematoidea could be alternatives for preventing Litopenaeus vannamei vibriosis caused by the bacterium Vibrio parahaemolyticus. Phytochemical screening was performed on methanolic extracts to qualitatively determine the main groups of bioactive compounds, previous to an in vitro antibacterial test against V. parahaemolitycus. Phenols, polyphenols, flavonoids, and the high presence of carbohydrates were found in both macroalgae. U. papenfussi showed more presence of lipids and alkaloids than U. nematoidea. Macroalgae extracts prepared (v:v) with a 1:1 methanol: dichloromethane solvent was used for the in vitro test using the disc diffusion method (MDD). Filter paper discs impregnated with 1.0, 1.5, 2.0, 3.0, and 4.0 mg of the extracts showed antibacterial activity against V. Parahaemolitycus in a dose-dependent manner in both macroalgae. The inhibition zone varied significantly (p < 0.05) from 8.33 ± 0.12 to 11.41 ± 0.73 mm for 1 to 3 mg of extract levels, respectively. In conclusion, both macroalgae have antibacterial activity in their crude extracts against this bacteria. It is suggested to evaluate it as a feed additive for L. vannamei. This study is the first report on a phytochemical screening and antibacterial activity of these macroalgae against V. parahaemolyticus.

Evaluation of Phytochemical Screening, Pigment Content, In Vitro Antioxidant, Antibacterial Potential and GC-MS Metabolite Profiling of Green Seaweed Caulerpa racemosa

Exploration of seaweeds to unravel their bioactive metabolites from the perspective of wider applications gained substantial importance. The present study was performed to investigate the total phenolic, flavonoid, tannin content, antioxidant activity and antibacterial potential of various solvent extracts of green seaweed Caulerpa racemosa. The methanolic extract showed higher phenolic (11.99 ± 0.48 mg gallic acid equivalents/g), tannin (18.59 ± 0.54 mg tannic acid equivalents/g) and flavonoid (33.17 ± 0.76 mg quercetin equivalents/g) content than other extracts. Antioxidant activity was determined by using 2,2-diphenylpicrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay with different concentrations of C. racemosa extracts. The methanolic extract showed higher scavenging potential in both the DPPH and ABTS activity with the inhibition value of 54.21 ± 1.39% and 76.62 ± 1.08%, respectively. Bioactive profiling was also identified by using Gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FT-IR) techniques. These studies revealed the presence of valuable bioactive compounds in C. racemosa extracts and these compounds might be responsible for antimicrobial, antioxidant, anticancer and anti-mutagenic properties. Major compounds identified in GC-MS were 3,7,11,15-Tetramethyl-2-hexadecen-1-ol, 3-hexadecene and Phthalic acid. In terms of antibacterial activity, C. racemosa has promising antibacterial potential against aquatic pathogens Aeromonas hydrophila, Aeromonas veronii and Aeromonas salmonicida. Further evaluation studies focusing aquatic related aspects would reveal the novel bioproperties and applications of C. racemosa.

Natural products as antivibrio agents: insight into the chemistry and biological activity

Vibriosis causes serious problems and economic loss in aquaculture and human health. Investigating natural products as antivibrio agents has gained more attention to combat vibriosis. The present review highlights the chemical diversity of antivibrio isolated from bacteria, fungi, plants, and marine organisms. Based on the study covering the literature from 1985-2021, the chemical diversity ranges from alkaloids, terpenoids, polyketides, sterols, and peptides. The mechanisms of action are included inhibiting growth, interfering with biofilm formation, and disrupting of quorum sensing. Relevant summaries focusing on the source organisms and the associated bioactivity of different chemical classes are also provided. Further research on in vivo studies, toxicity, and clinical is required for the application in aquaculture and human health.

The Chemotherapeutic Potentials of Compounds Isolated from the Plant, Marine, Fungus, and Microorganism: Their Mechanism of Action and Prospects

Research on natural products mainly focuses on developing a suitable drug to treat human disease. There has been a sharp increase in the development of drugs from natural products. Most of the drugs that are available are from the terrestrial origin. Marine natural products are less explored. Oceans are considered as a vast ecosystem with a wide variety of living organisms and natural products that are unexplored. Large numbers of antitumor drugs are from natural sources such as plants, marine, and microorganisms. 80% new chemical entities that were launched over the past 60 decades were from a natural source. In this article, the anticancer potential from the natural source such as plants, fungi, microorganisms, marine, and endophytes has been reviewed. Emphasis is given on the compound from the marine, plant, and of bacterial origin. Finally, we consider the future and how we might achieve better sustainability to alleviate human cancer suffering while having fewer side effects, more efficacies, and causing less harm than the present treatments.

The fate of antibiotic resistance genes, microbial community, and potential pathogens in the maricultural sediment by live seaweeds and oxytetracycline

Three common seaweeds including Ulva fasciata, Codium cylindricum and Ishige okamurai were used for the remediation of maricultural wastewater and sediment in the presence/absence of trace level of oxytetracycline (OTC) in lab-scale experiments. Higher NO₃^--N and PO₄^3--P removal rates were achieved due to the presence of seaweeds, and trace OTC also had a positive effect on NO₃^--N removal. A slight variation of 2.10-2.15% were observed in the total relative abundances of antibiotic resistance genes (ARGs) of different sediment samples after one-month operation. However, the variation of ARGs profiles by the co-existence of different seaweeds and OTC was in the descending order of Ishige okamurai > Codium cylindricum > Ulva fasciata, which was in accordance with the variation of microbial hosts at genus level. The abundance of dominant tetracycline resistance genes promoted by the co-existence of different seaweeds and OTC in compared with the presence of single seaweed or OTC via metagenomic sequencing and qPCR analysis, and the co-existence of Ishige okamurai and OTC exhibited the largest impact. The potential pathogens were more sensitive to the co-existence of seaweed and OTC than single seaweeds. Meanwhile, a variety of ARGs were enriched in the pathogens, and the dominant pathogenic bacteria of Vibrio had 133 Vibrio species with 28 subtypes of ARGs. The variation of ARGs profiles in the sediment were strongly related with the dominant phyla Proteobacteria, Actinobacteria, Firmicutes, Planctomycetes and Cyanobacteria. Besides, Nitrate level exhibited more significant effect on ∑ARGs, ARGs resistant to vancomycin and streptogramin_a, while phosphate level exhibited more positively significant effect on ARGs resistant to fosmidomycin, ATFBT and cephalosporin.

Anguilla sp. diseases diagnoses and treatments: The ideal methods at the crossroads of conservation and aquaculture purposes

Anguilla anguilla, A. japonica and A. rostrata are the most fished and consumed eel species. However, these species are Critically Endangered, Endangered and Endangered, respectively. A combination of factors is thought to be responsible for their decline including fisheries, climate change, habitat destruction, barriers to migration, pollution and pathogens. Among them, viruses, bacteria and parasites are causing weakening of wild eels and serious economic losses for fishermen and eel farmers. Early detection of pathogens is essential to provide appropriate responses both for conservation reasons and to limit economic losses. Classic diagnosis approaches are time consuming and invasive and usual treatments, for example, antipathogenic substances are becoming obsolete because of pathogen resistance and environmental impact problems. The need for early and non-invasive diagnostic methods as well as effective and environmentally friendly treatments has increased. Vaccine development and diet supplementation have known a growing interest since their use could allow prevention of diseases. In this review, we summarize the main pathogens-viruses, bacteria and parasites-of the three northern temperate eel species, the methods used to detect these pathogens and the different treatments used. We discussed and highlighted the need for non-invasive, rapid and efficient detection methods, as well as effective and environmentally friendly treatments for both conservation and aquaculture purposes.

Therapeutic Potential and Nutraceutical Profiling of North Bornean Seaweeds: A Review

Malaysia has a long coastline surrounded by various islands, including North Borneo, that provide a suitable environment for the growth of diverse species of seaweeds. Some of the important North Bornean seaweed species are Kappaphycus alvarezii, Eucheuma denticulatum, Halymenia durvillaei (Rhodophyta), Caulerpa lentillifera, Caulerpa racemosa (Chlorophyta), Dictyota dichotoma and Sargassum polycystum (Ochrophyta). This review aims to highlight the therapeutic potential of North Bornean seaweeds and their nutraceutical profiling. North Bornean seaweeds have demonstrated anti-inflammatory, antioxidant, antimicrobial, anticancer, cardiovascular protective, neuroprotective, renal protective and hepatic protective potentials. The protective roles of the seaweeds might be due to the presence of a wide variety of nutraceuticals, including phthalic anhydride, 3,4-ethylenedioxythiophene, 2-pentylthiophene, furoic acid (K. alvarezii), eicosapentaenoic acid, palmitoleic acid, fucoxanthin, β-carotene (E. denticulatum), eucalyptol, oleic acid, dodecanal, pentadecane (H. durvillaei), canthaxanthin, oleic acid, pentadecanoic acid, eicosane (C. lentillifera), pseudoephedrine, palmitic acid, monocaprin (C. racemosa), dictyohydroperoxide, squalene, fucosterol, saringosterol (D. dichotoma), and lutein, neophytadiene, cholest-4-en-3-one and cis-vaccenic acid (S. polycystum). Extensive studies on the seaweed isolates are highly recommended to understand their bioactivity and mechanisms of action, while highlighting their commercialization potential.

Anti-vibrio and immune-enhancing activity of medicinal plants in shrimp: A comprehensive review

Disease epidemics in shrimp aquaculture increase apace with the development of aquaculture systems throughout the world. The disease caused by Vibrio spp. (vibriosis) is considered the most devastating, which has made it the most feared bacterial disease in the shrimp sector. In aquaculture, several strategies have already been applied to control Vibrio strains, including chemicals, probiotics, antibiotics, natural products from plants, including plant oils; hence, there has been considerable attention for using plants in shrimp aquaculture to provide sustainable, eco-friendly and safe compounds, such as alkaloids, saponins, terpenoids and flavonoids for replacing chemical compounds and antibiotics in current aquaculture. Medicinal plants may also have immunostimulating activity, increase growth and resistance in shrimps. The present paper aims to review the inhibition of Vibrio spp. in shrimp by medicinal plants, using both in vitro or/and in vivo techniques. Several medicinal plants appear capable of inhibiting growth of Vibrio pathogens outside living shrimp or in the body of shrimp, through enhancing growth and immune capacity when shrimps are fed or injected with them. In the current review Gracilaria spp. (Gracilariaceae family) and Sargassum spp. (family Sargassaceae) have been used most for in vitro and in vivo experiments. Among the terrestrial plants, Eucalyptus camaldulensis, Psidium guajava, Rhodomyrtus tomentosa, and Syzygium cumini (Myrtaceae family) had significant activity against Vibrio.

Ecotoxicological assessment and dermal layer interactions of nanoparticle and its routes of penetrations

Our review focused on nanomaterials-based toxicity evaluation and its exposure to the human and aquatic animals when it was leached and contaminated in the environment. Ecotoxicological assessment and its mechanism mainly affect the skin covering layers and its preventive barriers that protect the foreign particles' skin. Nanoscale materials are essential in the medical field, especially in biomedical and commercial applications such as nanomedicine and drug delivery, mainly in therapeutic treatments. However, various commercial formulations of pharmaceutical drugs are manufactured through a series of clinical trials. The role of such drugs and their metabolites has not met the requirement of an individual's need at the early stage of the treatments except few drugs and medicines with minimal or no side effects. Therefore, biology and medicines are taken up the advantages of nano scaled drugs and formulations for the treatment of various diseases. The present study identifies and analyses the different nanoparticles and their chemical components on the skin and their effects due to penetration. There are advantageous factors available to facilitate positive and negative contact between dermal layers. It creates a new agenda for an established application that is mainly based on skin diseases.

Evaluation of the Potential of Marine Algae Extracts as a Source of Functional Ingredients Using Zebrafish as Animal Model for Aquaculture

Research on immunotherapeutic agents has become a focus for the treatment of fish diseases. The ability of algae to produce secondary metabolites of potential interest as immunotherapeutics has been documented. The present research intended to assess antiviral and antibacterial activities of macro- and microalgae extracts against viral and bacterial pathogens and explore their immunomodulatory potential using zebrafish (Danio rerio) larvae as a model organism. The cytotoxicity and antiviral activity of eight methanolic and ethanolic extracts from two macroalgae (Fucus vesiculosus, Ulva rigida) and two microalgae (Nannochloropsis gaditana, Chlorella sp.) were analyzed in established fish cell lines. Six extracts were selected to evaluate antibacterial activity by disk diffusion and growth inhibition assays. The three most promising extracts were characterized in terms of fatty acid composition, incorporated at 1% into a plant-based diet, and evaluated their effect on zebrafish immune response and intestinal morphology in a short-term feeding trial. All extracts exhibited in vitro antiviral activity against viral hemorrhagic septicemia and/or infectious pancreatic necrosis viruses. Methanolic extracts from F. vesiculosus and U. rigida were richer in saturated fatty acids and exhibited in vitro antibacterial action against several bacteria. Most promising results were obtained in vivo with F. vesiculosus methanol extract, which exerted an anti-inflammatory action when incorporated alone into diets and induced pro-inflammatory cytokine expression, when combined with the other extracts. Moreover, dietary inclusion of the extracts improved intestinal morphology. In summary, the results obtained in this study support the potential of algae as natural sources of bioactive compounds for the aquaculture industry.

Motility, biofilm formation and associated gene expression in Vibrio parahaemolyticus impaired by co-culture with live Ulva fasciata

AIMS

Vibrio parahaemolyticus is one of the most frequently occurred pathogens in mariculture. This study aimed to explore the mechanism of the impact of Ulva fasciata on the motility and biofilm formation of V. parahaemolyticus.

METHODS AND RESULTS

The inhibitory effect of U. fasciata on a V. parahaemolyticus, isolated from clam maricultural sediment, was examined by co-culture of them. The live U. fasciata significantly inhibited the swimming behaviour, twitching behaviour and biofilm formation of V. parahaemolyticus JF, with inhibition rates range of 2.48%-20.26%, 1.59%-39.18% and 28.3%-94.7% under different nitrate and phosphate levels, respectively. The results of transcriptome sequencing showed that 210 significantly differentially expressed genes (DEGs) were found in strain JF between the presence and absence of U. fasciata, including 90 upregulated genes and 120 downregulated genes. According to GO (Gene Ontology) function enrichment and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis, the downregulated genes of JF were partially enriched in flagella assembly (fliC, fliK, fliG, fliN, fliH, fliI, fliJ and fliA), bacterial chemotaxis (mCP, cheB, cheW and cheY) and biofilm formation (fliA/σ²⁸ and eps), which explained the suppressed motility and biofilm formation of V. parahaemolyticus JF under U. fasciata stress.

CONCLUSIONS

Live U. fasciata significantly impaired the motility and biofilm formation of V. parahaemolyticus, which could occur in niches with either sufficient or inadequate nutrient (nitrate and phosphate) concentrations. The DEGs of V. parahaemolyticus modulated by U. fasciata were enriched mainly in the flagellar assembly, bacterial chemotaxis and biofilm pathways.

SIGNIFICANCE AND IMPACT OF THE STUDY

New information on how V. parahaemolyticus respond to U. fasciata regarding motility and adhesion behaviours, and the mechanism of that was firstly explored in this study. The results suggested that the seaweed U. fasciata has promising prospects as an environmentally friendly preventive measure to treat vibriosis in mariculture.

COMPREHENSIVE ASSESSMENT OF QUALITY AND SAFETY OF BERRY SAUCE WITH IODINE-CONTAINING ADDITIVE

One of the acute problems of our time is iodine deficiency in human nutrition, which is typical for both countries with economies in transition and economically developed ones. Today, about a third of the world's population live in conditions of natural iodine deficiency. The most common solution to iodine deficiency is salt iodization, but this can lead to excessive iodine intake. In addition, it is much healthier to eat organic iodine, which is found in large quantities in brown algae. It is the development of new types of food products using brown algae as a biologically active additive that is a new promising direction for solving the problem of insufficient iodine consumption. Taking into account the relevance of solving the problem of iodine deficiency and the constantly growing demand for fruit and berry sauces, the technology of berry sauces based on blueberries, cranberries, dogwood, sea buckthorn and viburnum with the addition of brown algae has been developed. However, the mass introduction into production and consumption of the developed sauces will make a significant contribution to solving the global problem of insufficient consumption of organic iodine, requires research to establish their compliance with the typical quality and safety indicators for these products. The physicochemical indicators of the developed berry sauces were investigated, confirming the high quality in terms of the content of soluble solids – 25.0 ... 28.5%, the mass fraction of titratable acids – 1.9%, and indicate the complete absence of mineral, vegetable and foreign substances in the product. It was found that the developed sauces with iodine-containing algal additive have high microbiological quality indicators when stored for up to 14 days, even without adding preservatives. The complete safety of the developed berry sauces was established in terms of the content of toxic elements, as well as the absence of genetically modified organisms in the finished product

Isolation, characterization, and efficacy of bacteriophages isolated against Citrobacter spp. an in vivo approach in a zebrafish model (Danio rerio)

Citrobacter infections are becoming an increasingly significant health problem in aquaculture in South-Eastern countries. The objective of this study was to isolate and evaluate the potential of lytic bacteriophages against Citrobacter infections. TEM analysis revealed that the isolated phages Citrophage MRM19 and Citrophage MRM57 were identified to be Siphovirus and Podovirus family of the order Caudovirales. The phage life-cycle studies showed that Citrophage MRM19 had an adsorption time of 18 ± 1 min and a latency period of 25 ± 3 min with burst size of 110 ± 20 phages/infected cell and Citrophage MRM57 had an adsorption time of 15 ± 1 min and a latency period of 25 ± 2 min with burst size of 50 ± 5 phages/infected cell. In vitro studies indicated that the bacterial load was reduced by 5 and 7 log units within 12 h by Citrophage MRM19 and Citrophage MRM57. The in vivo efficacy of the phages was studied using zebrafish (Danio rerio) as a model organism in low-scale tanks. The study unveiled that the use of phages increased the survival up to 17%, 23%, and 26% in the case of Citrophage MRM19, Citrophage MRM57, and phage cocktail treatment, respectively. Our study indicated that bacteriophages are suitable biocontrol agents against Citrobacter spp. especially in aquaculture industry.

Peptide identification from a Porphyra dioica protein hydrolysate with antioxidant, angiotensin converting enzyme and dipeptidyl peptidase IV inhibitory activities

A Porphyra dioica protein extract was enzymatically hydrolysed and then fractionated using semi-preparative reverse-phase high performance chromatography. The hydrolysate and its fractions were tested for their oxygen radical absorbance capacity (ORAC) along with their angiotensin converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV) inhibitory activities. The most potent fraction was analysed by liquid chromatography mass spectrometry. Eight peptide sequences were selected for synthesis based on their structure-activity criteria for bioactivity. Asp-Tyr-Tyr-Lys-Arg showed the highest ORAC activity (4.27 ± 0.15 μmol Trolox equivalent per μM). Thr-Tyr-Ile-Ala had the highest ACE inhibitory activity (IC50: 89.7 ± 7.10 μM). Tyr-Leu-Val-Ala was the only peptide showing DPP-IV inhibitory activity (IC50: 439 ± 44 μM). Apart from Asp-Tyr-Tyr-Lys-Arg and Thr-Tyr-Ile-Ala, which displayed increased ORAC activity, the bioactivities of the peptides were either maintained or decreased following in vitro simulated gastrointestinal digestion. The results indicate that P. dioica-derived peptides may have potential applications as health enhancing ingredients.

Effects of thymol supplementation on performance, mortality and branchial energetic metabolism in grass carp experimentally infected by Aeromonas hydrophila

We determined whether thymol supplementation of would minimize the negative effects of Aeromonas hydrophila infection on branchial energy metabolism, weight loss and mortality in grass carp (Ctenopharyngodon idella). We found that the infected fish all died, while 62.5% of those supplemented with 100 mg/kg thymol survived. Cytosolic and mitochondrial creatine kinase (CK) activities, as well as adenylate kinase (AK) and pyruvate kinase (PK) activities were significant lower in gills of A. hydrophila-infected fish than those of the control group, and adenosine triphosphate (ATP) levels were significant lower in the infected group. Finally, branchial reactive oxygen species (ROS) were significant higher in A. hydrophila-infected fish than in the control group. Supplementation with 100 and 300 mg thymol/kg diet prevented inhibition of branchial cytosolic and mitochondrial CK activities caused by infection, and also inhibited the reduction of branchial ATP levels. Supplementation with 100, 200 and 300 mg thymol/kg prevented the inhibition of branchial AK and PK activities induced by aeromonosis. Supplementation of 100 mg thymol/kg prevented weight loss after A. hydrophila infection. These data suggest that supplementation with 100 mg thymol/kg exerts potent bactericidal properties and augments longevity. Supplementation at all concentrations of thymol prevented A. hydrophila-induced branchial bioenergetics; nevertheless, higher concentrations were associated with side-effects.

Antiviral activity of cathelicidin 5, a peptide from Alligator sinensis, against WSSV in caridean shrimp Exopalaemon modestus

White spot disease caused by white spot syndrome virus (WSSV) is responsible for harming shrimp aquaculture industry and results in a pandemic throughout the world. Cathelicidin 5 treatment enhanced immune parameters including antioxidant enzyme activity and immune-related genes expression in shrimp Exopalaemon modestus. Shrimp treated with cathelicidin 5 and inoculated with white spot syndrome virus (WSSV) exhibited a significantly lower mortality rate and lower viral VP28 amplification and expression than control. This study addresses the role of cathelicidin 5 in immune stimulatory and antiviral activities that could protect E. modestus from WSSV infection.

RESEARCH OF THE SAFETY INDICATORS OF BERRY SAUCES WITH SEAWEED’S RAW MATERIALS

The current thing now is the matter regarding enrichment of food products with organic iodine, which is caused by iodine deficiency in the food ration of most of the country's population and by the country-wide radionuclide pollution, which leads to a hundredfold increase of risks of the thyroid body radiation. In this regard, there were developed the technologies of the berry sauces with the addition of the seaweed’s raw materials, as the iodine-concentrating component. The technologies of blueberry-cranberry sauces with guelder-rose juice, cornel-bilberry sauce with guelder-rose juice and blueberry-buckthorn sauce with guelder-rose juice were developed. This work is dedicated to a research of safety indicators of the developed sauces. There were used the hydrated seaweeds of Laminaria, of Fucus, of Undaria pinnatifida as iodinated additives. The following microbiological indicators were determined: the quality of mesophilic aerobic and optionally anaerobic microorganisms (МAOАnM), mold, yeast and lactic acid bacteria, and the presence of the coliform bacteria (CB) bacteria. The study results showed, that there are no microorganisms in the finished products, which may result the damage of the product after pasteurization. It was identified, that the own organic acids of the prepared sauces will be sufficient to ensure the microbiological clearness and the use of the additional preserving agents does not make sense. Toxicological indicators, namely the mass fractions of lead, cadmium, arsenic and mercury, have been studied. It has been established that the content of toxic elements in test samples is hundreds of times less than permissible. The toxicological indicators were studied, namely, the mass fractions of lead, cadmium, arsenic and mercury. It was identified, that the content of toxic elements in test samples is hundreds of times less than permissible. Thus, it is proved that the sauces made according to the developed technology, comply with the requirements of the regulatory documents according to the safety indicators. Moreover, it is proved, that that the addition of the seaweed’s raw materials does not worsen these indicators. To confirm the obtained data, the sample with the highest seaweed content was examined by an independent laboratory accredited according to DSTU ISO/IEC 17025 with the issuance of the appropriate test report.

Effects of a co-culture of marine algae and shrimp (Litopenaeus vannamei) on the growth, survival and immune response of shrimp infected with Vibrio parahaemolyticus and white spot virus (WSSV)

In aquaculture, fighting infectious diseases is a necessity. This study measured the immuno-stimulating effect of live macroalgae consumption on Litopenaeus vannamei against Vibrio parahaemolyticus and WSSV infection in two independent bioassays. Shrimps and macroalgae were cultivated in a co-culture with two species of macroalgae separately (Gracilaria vermiculophylla and Dictyota dichotoma), and later, shrimp were infected with V. parahaemolyticus. In another bioassay, shrimp and macroalgae (G. vermiculophylla, D. dichotoma and Ulva lactuca) were grown and subsequently infected with WSSV. For both bioassays, survival after 120 h was determined, the total hemocyte count (TCH) was measured and the activity of superoxide dismutase (SOD) and catalase (CAT) in tissue were measured. The results indicate that the use of macroalgae in co-culture with L. vannamei provides a nutritional benefit that achieves higher growth than the control organisms, as well as improvements of the ammonium concentration and immune response after infection with V. parahaemolyticus and WSSV. A better immune response was obtained in organisms cultured with macroalgae in both bioassays at a ratio of 1.6-1.9 for organisms infected with bacteria and 1.4 to 1.6 times for organisms infected with the virus. In turn, the enzymatic activity of SOD and CAT were higher in the treated organisms relative to the controls in both experiments.

Mucosal immune parameters, immune and antioxidant defence related genes expression and growth performance of zebrafish (Danio rerio) fed on Gracilaria gracilis powder

In the present study zebrafish (Danio rerio) has been used as model organism to establish the effects of dietary supplementation of Gracilaria gracilis powder (GP) on mucosal and innate immune parameters, antioxidant enzymes, and growth. In order to establish these features, zebrafish were fed for eight weeks with experimental diets containing different levels of Red algae, 0.25, 0.5 and 1% of GP; also, a group was fed with control diet. At the end of the experimental period the antioxidant superoxide dismutase and catalase (SOD, CAT) genes expression, interleukin 1 beta (il-1β), 
lysozyme (LYZ), tumor necrosis factor alpha (TNF-α) for immune-related genes expression, total immunoglobulin (Ig), total protein, 
alkaline phosphatase (ALP) activity for innate immune parameters, and growth performance have been established. The GP dietary supplementation showed differences in SOD and CAT expression in zebrafish whole body respect to the control group. Non-signifcant differences were noticed among the different groups in case of TNF-α, LYZ and il-1expression (P > 0.05). The skin mucus total Ig and total protein in the group fed on 1% of GP were significantly higher respect to control group (P < 0.05). 0.25 and 0.5% of GP dietary supplementation significantly enhanced skin mucus ALP activity levels (P < 0.05). No significant differences were recorded for growth performances among groups (P > 0.05). The results obtained in the present study revealed that G. gracilis could be takes in account as fishes diet supplementation for its immune system stimulants effects.

Effects of orange peels derived pectin on innate immune response, disease resistance and growth performance of Nile tilapia (Oreochromis niloticus) cultured under indoor biofloc system

The present study investigates the effects of orange peels derived pectin (OPDP) on skin mucus and serum immune parameters, disease resistance and growth performance of O. niloticus cultured under indoor biofloc system. Six hundred Nile tilapia (average weight 9.09 ± 0.05 g) were distributed into 15 fiber tanks (300 L per tank) assigned to five treatments repeated in triplicate. Fish were fed experimental diets contain different levels OPDP as follows: 0 (control in clear water), 0 (control in biofloc system), 5, 10, and 20 g kg^-1 OPDP for 8 weeks. At weeks 4 and 8 post feeding, skin mucus lysozyme (SMLA), peroxidase activities (SMPA), serum lysozyme (SL), serum peroxidase (SP), alternative complement (ACH50), phagocytosis (PI), and respiratory burst activities (RB) as well specific growth rate (SGR), weight gain (WG), final weight (FW), and feed conversion ratio (FCR) were measured. Also, resistance against Streptococcus agalactiae was assessed after 8 weeks post-feeding. Nile tilapia fed OPDP supplemented diets had significantly higher SMLA and SMPA compared to the controls (P < 0.05). The maximum values were observed in tilapia fed 10 g kg^-1 OPDP followed by 5 and 20 g kg^-1 OPDP. Nevertheless, no significant differences were observed between these two supplemented diets and between the control groups (P > 0.05). Regarding the serum immunological parameters, dietary inclusion of 10 g kg^-1 OPDP showed significant higher SL and PI than other supplemented groups and control groups (P < 0.05). However, no significant differences were observed in SL and PI of fish fed 5 and 20 g kg^-1 OPDP (P > 0.05). Dietary administration of OPDP significantly increased SP and ACH50 compared to the controls (P < 0.05), regardless of inclusion level. Additionally, non-significant change was found in RB of OPDP fed fish when compared with the controls (P > 0.05). The challenge test revealed that relative percent of survival (RPS) in OPDP treatments were 45.45%, 81.82%, 50%, respectively. The highest RPS was noticed in fish fed 10 g kg^-1 OPDP. Furthermore, dietary administration of OPDP significantly improved SGR, WG, FW, and FCR (P < 0.05). Overall, the present findings suggested that OPDP can be taken into account as functional feed additives for O. niloticus.