Disease Management In Aquaculture Research Articles

IgT-mediated mucosal immunity and microbiota dynamics in snakehead (Channa argus) post Aeromonas veronii TH0426 and Aeromonas hydrophila TPS infection: implications for aquaculture disease management.

The aquaculture sector, vital to global food security, grapples with bacterial pathogens compromising fish health and industry sustainability. This investigation probes mucosal immune responses and gut microbiota dynamics in snakehead (Channa argus) post-Aeromonas infection, a prevalent aquaculture challenge. Employing infection models, we delineated the integral role of immunoglobulin T (IgT) in mucosal immunity and its interaction with gut microbiota. Fish from a local farm, maintained under controlled conditions, were infected with Aeromonas veronii TH0426 and Aeromonas hydrophila TPS. Post-infection, daily monitoring and sample collection at specified intervals were conducted for comprehensive analysis. Histopathology, quantitative PCR, immunofluorescence, and microbiota profiling revealed significant immune and microbial changes, particularly at day 7. Intestinal IgT, IgM, and pIgR gene expression surged, indicative of a robust response. Immunofluorescence microscopy confirmed increased IgT+ and pIgR+ cell infiltration in the epithelium. Post-infection dysbiosis, with altered bacterial composition, was partially offset by elevated IgT levels. These insights underscore IgT's crucial function in mucosal defense and suggest potential for probiotic and vaccine strategies to enhance aquaculture disease resilience.

A Novel Beta-Defensin Isoform from Malabar Trevally, Carangoides malabaricus (Bloch & Schneider, 1801), an Arsenal Against Fish Bacterial Pathogens: Molecular Characterization, Recombinant Production, and Mechanism of Action.

Antimicrobial peptides (AMPs), including beta-defensin from fish, are a crucial class of peptide medicines. The focus of the current study is the molecular and functional attributes of CmDef, a 63-amino acid beta-defensin AMP from Malabar trevally, Carangoides malabaricus. This peptide demonstrated typical characteristics of AMPs, including hydrophobicity, amphipathic nature, and +2.8 net charge. The CmDef was recombinantly expressed and the recombinant peptide, rCmDef displayed a strong antimicrobial activity against bacterial fish pathogens with an MIC of 8µM for V. proteolyticus and 32µM for A. hydrophila. The E. tarda and V. harveyi showed an inhibition of 94% and 54%, respectively, at 32µM concentration. No activity was observed against V. fluvialis and V. alginolyticus. The rCmDef has a multimode of action that exerts an antibacterial effect by membrane depolarization followed by membrane permeabilization and ROS production. rCmDef also exhibited anti-cancer activities in silico without causing hemolysis. The peptide demonstrated stability under various conditions, including different pH levels, temperatures, salts, and metal ions (KCl and CaCl2), and remained stable in the presence of proteases such as trypsin and proteinase K at concentrations up to 0.2µg/100µl. The strong antibacterial efficacy and non-cytotoxic nature suggest that rCmDef is a single-edged sword that can contribute significantly to aquaculture disease management.

Review Paper on Recent Advances of Biotechnology Application to Aquaculture Development

Recent advances in biotechnology have significantly impacted aquaculture production, revolutionizing the industry. which explores key developments in applying biotechnological tools to enhance various aspects of aquaculture. Molecular techniques, such as genetic manipulation, have enabled the selective breeding of fish for desirable traits, improving growth rates, disease resistance, and overall productivity. Furthermore, the application of advanced genomics and bioinformatics has facilitated the identification of specific genes associated with important traits, paving the way for precision breeding. Biotechnological interventions also extend to disease management in aquaculture. Novel diagnostic methods based on molecular biology enable early detection of pathogens, contributing to effective disease prevention and control. Vaccines developed through biotechnological approaches have shown promise in protecting aquatic species against various infections, reducing reliance on traditional antibiotics. Nutrition is another critical aspect benefiting from biotechnological advancements. Genetically engineered feed formulations, enriched with essential nutrients, enhance the overall health and growth of aquaculture species. Furthermore, by enhancing feed conversion efficiency and waste management, probiotics and prebiotics obtained from biotechnological processes aid in the development of sustainable and ecologically friendly practices. Aquaculture and biotechnology are integrated in environmental conservation and monitoring projects. Aquatic organisms are guaranteed ideal conditions through real-time water quality monitoring made possible by biosensors and molecular tools. Utilizing genetically engineered organisms, bioremediation techniques help to lessen the negative environmental effects of aquaculture operations. In conclusion, recent advances in biotechnology have propelled aquaculture towards a more sustainable, efficient, and environmentally conscious industry. The integration of molecular techniques, genetic manipulation, diagnostics, and environmental monitoring has opened new avenues for addressing challenges and optimizing production in aquaculture. The continued exploration and application of biotechnological tools hold great promise for the future of this crucial food production sector.

Recent advances of Terminalia catappa and its application in fish culture: A review

AbstractHigh‐intensity aquaculture may cause the aquatic animals to experience elevated stress levels, which in turn will increase their susceptibility to illness and result in substantial losses. Farmers frequently use chemical and antibiotic treatments for fish diseases, which have led to drug‐resistant and hazardous residues in farmed fish and the environment. Consequently, finding substitutes for chemicals and antibiotics is crucial for disease management in aquaculture. Terminalia catappa L. or commonly called Indian almond is well known for its medicinal properties and widely distributed in tropical and subtropical regions. T. catappa contains chemical compounds such as tannin and flavonoid that play an important role in antibacterial, anti‐allergy, anti‐inflammation, and anti‐cancer. Numerous studies have been conducted on leaves, bark, fruits, and seed of T. catappa for their applications, including medicinal, bioremediation (dye absorption), and aquaculture use. Much research can be found on the utilization of T. catappa leaves to improve fish well‐being, mostly in the ornamental fish industry. Extract of T. catappa has been found to improve fish survival, growth rate, inhibit bacterial infection, improve water quality, enhance fish colouration, and boost the immune response. Although T. catappa leaves have undergone substantial research, it has not been systematically described in connection to fish species used in aquaculture. This review will systematically discuss the biotoxicity of T. catappa evaluation of growth‐promoting properties, eggs and larviculture performance, and enhancement of fish resistance to various bacteria, fungi, and parasites. In addition, the article also highlights the future perspectives of using T. catappa to improve fish culture.

Antibiotic Alternatives for Controlling Bacterial Infections in Aquaculture

Purpose: The general purpose of this study was to investigate antibiotic alternatives for controlling bacterial infections in aquaculture.
 Methodology: The study adopted a desktop research methodology. Desk research refers to secondary data or that which can be collected without fieldwork. Desk research is basically involved in collecting data from existing resources hence it is often considered a low cost technique as compared to field research, as the main cost is involved in executive’s time, telephone charges and directories. Thus, the study relied on already published studies, reports and statistics. This secondary data was easily accessed through the online journals and library.
 Findings: The findings reveal that there exists a contextual and methodological gap relating to antibiotic alternatives for controlling bacterial infections in aquaculture. Preliminary empirical review revealed that various alternative strategies, including probiotics, phage therapy, herbal extracts, and immunostimulants, showed promise in managing bacterial infections and promoting aquaculture sustainability. It emphasized the importance of adopting a multifaceted approach and conducting further research to optimize the efficacy and scalability of antibiotic alternatives. Additionally, interdisciplinary collaboration was highlighted as essential for driving innovation and facilitating the development of sustainable disease management strategies. Overall, the study underscored the urgency of transitioning towards antibiotic alternatives to mitigate risks, promote environmental sustainability, and ensure long-term seafood production viability.
 Unique Contribution to Theory, Practice and Policy: The Systems theory, Social-Ecological Systems theory and Ecological Resilience theory may be used to anchor future studies on antibiotic alternatives for controlling bacterial infections in aquaculture. This study has contributed significantly to theoretical advancements, practical applications, and policy development. By exploring various theoretical frameworks such as systems theory, social-ecological systems theory, and resilience theory, the research provided insights into the complex dynamics of disease management in aquaculture. Recommendations were made to integrate antibiotic alternatives into holistic disease management strategies tailored to specific aquaculture systems and target species. Practical guidelines were proposed for the selection, formulation, and administration of antibiotic alternatives, while policy recommendations emphasized the need for regulatory frameworks that support sustainable aquaculture practices. Overall, the study informed future research directions and policy initiatives aimed at promoting the responsible use of antibiotic alternatives and enhancing the resilience of aquaculture systems.
 Keywords: Antibiotic Alternatives, Bacterial Infections, Aquaculture, Disease Management, Systems Theory, Social-Ecological Systems Theory, Resilience Theory, Practical Applications, Regulatory Frameworks, Sustainability, Holistic Management, Research Directions

Evaluation of CpG-Oligodeoxynucleotides as Immunostimulants and Protecting Agents Against Aeromonas hydrophila in Freshwater Lobster (Cherax quadricarinatus)

MAS disease (Motyle Aeromonas hydrophila) is a prevalent bacterial infection that affects freshwater lobsters. This research aimed to evaluate the potential of CpG-ODN as an immunostimulant and protecting agent in Cherax quadricarinatus lobsters. The study was conducted at the Fish Health Laboratory, Pangkep State Polytechnic, Indonesia. The lobsters were divided into different groups and injected with three types of CpG-ODN (2133, 2006, 1668) or a control group using PBS. Parameters such as Total Hemocyte Count, Phagocytic Index, and Lysozyme Activity were measured at multiple time points, including before and after injection. CpG-ODN 2006 showed significant immunostimulant effects, as evidenced by a notable increase in total hemocyte count, phagocytic index, and lysozyme activity compared to the other CpG-ODN types. On the other hand, CpG-ODN 2133 exhibited potential as a protecting agent against Aeromonas hydrophila, as lobsters injected with this CpG-ODN demonstrated higher survival rates in the challenge test compared to the control group. These findings contribute to our understanding of immunostimulant strategies and protective mechanisms in freshwater lobsters. CpG-ODN, particularly CpG-ODN 2006, shows promise as an effective immunostimulant, while CpG-ODN 2133 exhibits potential as a protecting agent against A. hydrophila. Further exploration of CpG-ODN applications could lead to advancements in disease management in aquaculture.

Anti-pathogenicity of Acanthus ilicifolius leaf extracts against A. hydrophila infection in Labeo rohita fingerlings

Antibiotic resistance has become one of the inevitable barrier in aquaculture disease management. Herbal drugs has evolved to be the novel ways of combating drug resistant pathogens. In the current investigation, leaf extracts of mangrove plant, Acanthus ilicifolius were assessed for in vitro studies, among the selected four extracts, methanol extract has expressed highest antibacterial activity against P .aeruginosa (4 ± 0.3 mm), A. hydrophila (5.9 ± 0.5 mm), S. aureus (3.5 ± 0.7 mm) and B. subtilis (2.9 ± 0.5 mm) and antioxidant activity, DPPH (81.3 ± 1.0 AAEµg/ml) and FRAP (139.1 ± 1.5 AAEµg/ml).TPC and TFC were higher in the methanolic extract and has exhibited positive correlation with both DPPH and FRAP assays. Considering the in vitro efficiency, methanol extract was purified successively by column and thin layer chromatography and characterisation by GC–MS unveiled the presence of 2-Propanethiol, Trimethylphosphine, Pentanoyl chloride, Dimethylhydroxymethylphosphine and Propanedinitrile, ethylidene. A. hydrophila infected L. rohita fingerlings has survival percentage 81% and 94% in extract treated groups over 0% in negative control and 71% in positive control.

Economic impact of disease on small-scale catfish farms in Nigeria

Disease outbreaks are a key menace in aquaculture, capable of causing huge economic losses to the farms. However, its economic impact on small-scale catfish farms has not received enough researchers' attention. Therefore, this study quantifies the economic value of disease outbreaks at different levels, investigates the economic performance of fish farms at different mortality rates, assesses the effect of disease outbreaks on profitability, and identifies the constraints faced by farmers in preventing and controlling aquaculture disease in Nigeria. Data were collected from 240 catfish farms and analysed with descriptive statistics, profitability analysis, Kruskal-Wallis test, and beta regression. The results revealed that the catfish farms encountered disease occurrences at different levels, with a mortality rate ranging from 1.86% to 19.73%, which was valued at USD 192.79 to USD 2056.38 per production cycle, respectively. The economic performance of the small-scale catfish farms reduced as the disease outbreak increased, which was indicated by the fact that the catfish farms with a low mortality rate had a higher profit than those with a high mortality rate. The regression analysis further revealed that the disease outbreak, proxy with mortality rate, mortality value, treatment cost, water cost, and transportation cost, had a negative and significant effect on catfish farms' profitability. The major severe barriers faced by catfish farmers in preventing and controlling disease on their farm were a lack of aquaculture disease management training, the non-availability of effective drugs within the reach of the farmers, the high cost of quality feeds, the high cost of drugs and treatment, and poor credit facilities. These results indicate the need for catfish farmers to be well-trained in aquaculture disease management by research institutes and extension agents to reduce the occurrence of disease outbreaks and increase their farms' economic performance.

A detailed look at the impacts of biofloc on immunological and hematological parameters and improving resistance to diseases

The innate immunity of invertebrates serves as a critical trait that provides a valuable foundation for studying the common biological responses to environmental changes. With the exponential growth of the human population, the demand for protein has soared, leading to the intensification of aquaculture. Regrettably, this intensification has resulted in the overuse of antibiotics and chemotherapeutics, which have led to the emergence of resistant microbes or superbugs. In this regard, biofloc technology (BFT) emerges as a promising strategy for disease management in aquaculture. By harnessing the power of antibiotics, probiotics, and prebiotics, BFT offers a sustainable and eco-friendly approach that can help mitigate the negative impacts of harmful chemicals. By adopting this innovative technology, we can enhance the immunity and promote the health of aquatic organisms, thereby ensuring the long-term viability of the aquaculture industry. Using a proper carbon to nitrogen ratio, normally adding an external carbon source, BFT recycles waste in culture system with no water exchange. Heterotrophic bacteria grow along with other key microbes in the culture water. Heterotrophs play a major role in assimilating ammonia from feed and fecal waste, crucial pathway to form suspended microbial aggregates (known as 'biofloc'); while chemoautotrophs (e.g. nitrifying bacteria) oxidize ammonia into nitrite, and nitrite into nitrate promoting a healthy farming conditions. By using a highly aerated media and an organic substrates that contain carbon and nitrogen, protein-rich microbes are able to flocculate in culture water. Several types of microorganisms and their cell components have been studied and applied to aquatic animals as probiotics or immunostimulants (lipopolysaccharide, peptidoglycan, and 1-glucans) to enhance their innate immunity and antioxidant status, thereby enhancing their resistance to disease. In recent years, many studies have been conducted on the application of BFT for different farmed aquatic species and it has been observed as a promising method for the development of sustainable aquaculture, especially due to less use of water, increased productivity and biosecurity, but also an enhancement of the health status of several aquaculture species. This review analyses the immune status, antioxidant activity, blood and biochemical parameters, and level of resistance against pathogenic agents of aquatic animals farmed in BFT systems. This manuscript aims to gather and showcase the scientific evidences related to biofloc as a 'health promoter' in a unique document for the industry and academia.

Disease prevention and mitigation in US finfish aquaculture: A review of current approaches and new strategies

AbstractIn the United States, the aquaculture industry has not seen the same levels of growth in production as other countries—made evident by the $17 billion seafood trade deficit estimated in 2020. Nevertheless, aquaculture remains an important industry fully capable of supplementing the domestic seafood supply and reducing the US seafood trade deficit. Infectious diseases is one of several factors that threatens the capability and sustainability of the aquaculture industry, highlighting the importance of effective control strategies for these pathogens. Antimicrobial products are often used to control and eliminate undesirable microbes in effort to prevent or mitigate the impacts of infectious diseases. Some pathogens are capable of adapting to and resisting the antimicrobial effects, escalating the challenges associated with disease management in aquaculture. Antimicrobial resistance (AMR) is now recognised by numerous national and international agencies as a top global health concern and is problematic for US aquaculture. Currently, disease prevention and mitigation strategies utilised by US finfish aquaculture can be broken down into three levels; comprehensive protocols (biosecurity, disease response), good husbandry strategies (stress management, proper diet, optimal environment) and effective antimicrobial products (biocides, therapeutics). This review will discuss how each level contributes differently to the overall protection of fish from pathogens. In the era of AMR, this review will also highlight current and emerging alternative strategies that do not rely on traditional antimicrobial products (e.g., vaccines, dietary supplements, novel antimicrobial, stock selection) for disease prevention and mitigation.

Research pre-empting parasite adaptation is key to sustainable disease management in aquaculture

As the aquaculture sector continues to expand, there is likely to be a growing need to combat infectious diseases. The desire for rapid and effective results means that any concerns about longer-term effects of disease controls are often sidelined. In particular, the well-documented capacity for parasites and pathogens to evolve treatment resistance must not be ignored in aquaculture. Outbreaks of resistant parasites pose significant threats to the environment, as well as to farm production. If an industry wishes to avoid treatment resistance, there must first be committed research into the evolutionary biology of the parasite species. Such research should be incorporated into the early phases of developing and implementing a treatment strategy—the sooner the risk of resistance is identified, the sooner its impacts on aquaculture can be mitigated. Here I discuss a research framework that can help guide this process. A combination of theoretical (reviewing the literature), empirical (testing for heritable resistance) and modelling (simulating evolutionary dynamics) studies is recommended. Armed with the knowledge from these studies, parasite management strategies can then be optimised at a regional scale (e.g. with refugia or treatment combinations) in ways that minimise the potential for adaptation. The interaction between salmonid aquaculture and parasitic sea lice is an ideal case study for this topic, and the insights gained from this system should be considered across aquaculture industries. Nevertheless, there is no one-size-fits-all solution to treatment resistance. For each system, dedicated research into parasite evolutionary biology—with a research framework as a guide—is required for aquaculture to home in on the most sustainable disease management strategies for the future.

The many challenges of disease management in aquaculture

The many challenges of disease management in aquaculture

An overview of chemicals and drugs in aquaculture disease management

An overview of chemicals and drugs in aquaculture disease management

CRISPR-Cas Genome Editing Technique for Fish Disease Management: Current Study and Future Perspective.

Scientists have discovered many ways to treat bacteria, viruses, and parasites in aquaculture; however, there is still an impossibility in finding a permanent solution for all types of diseases. In that case, the CRISPR-Cas genome-editing technique can be the potential solution to preventing diseases for aquaculture sustainability. CRISPR-Cas is cheaper, easier, and more precise than the other existing genome-editing technologies and can be used as a new disease treatment tool to solve the far-reaching challenges in aquaculture. This technique may now be employed in novel ways, such as modifying a single nucleotide base or tagging a location in the DNA with a fluorescent protein. This review paper provides an informative discussion on adopting CRISPR technology in aquaculture disease management. Starting with the basic knowledge of CRISPR technology and phages, this study highlights the development of RNA-guided immunity to combat the Chilodonella protozoan group and nervous necrosis virus (NNV) in marine finfish. Additionally, we highlight the immunological application of CRISPR-Cas against bacterial diseases in channel catfish and the white spot syndrome virus (WSSV) in shrimp. In addition, the review summarizes a synthesis of bioinformatics tools used for CRISPR-Cas sgRNA design, and acceptable solutions are discussed, considering the limitations.

Isolation and identification of a new strain of nervous necrosis virus from the big-belly seahorse Hippocampus abdominalis

BackgroundBetanodaviruses, members of the Nodaviridae family, are the causative agents of viral nervous necrosis in fish, resulting in great economic losses worldwide.MethodsIn this study, we isolated a virus strain named seahorse nervous necrosis virus (SHNNV) from cultured big-belly seahorses Hippocampus abdominalis in Xiamen city, Fujian Province, China. Virus isolation, PCR detection, phylogenetic analysis, qRT-PCR, fluorescence in situ hybridization and histology were used for virus identification and analysis of virus histopathology. Furthermore, an artificial infection experiment was conducted for virulence testing.ResultsBrain and eye tissue homogenates of diseased big-belly seahorses were inoculated onto a grouper spleen (GS) cell monolayer at 28 °C. Tissue homogenates induced obvious cytopathic effects in GS cells. PCR and sequencing analyses revealed that the virus belonged to Betanodavirus and shared high sequence identity with red-spotted grouper nervous necrosis virus isolates. qRT-PCR and fluorescence in situ hybridization revealed that SHNNV mainly attacked the brain and eye. Histopathological examination revealed that the virus led to cytoplasmic vacuolation in the brain and retinal tissues. Infection experiments confirmed that SHNNV was highly infectious, causing massive death in big-belly seahorses.ConclusionA novel seahorse betanodavirus from the big-belly seahorse cultured in China was discovered. This finding will contribute to the development of efficient strategies for disease management in aquaculture.

Phytotherapy and combined nanoformulations as a promising disease management in aquaculture: a review

Phytotherapy and combined nanoformulations as a promising disease management in aquaculture: a review

Tissue‐specific differences in detection of Yersinia ruckeri carrier status in rainbow trout (Oncorhynchus mykiss)

Effective monitoring for subclinical infections is a cornerstone of proactive disease management in aquaculture. Salmonid fish that survive enteric redmouth disease (ERM) can carry Yersinia ruckeri as a latent infection for several months, potentially facilitating cryptic spread between facilities that exchange fish. In this study, fingerling rainbow trout (Oncorhynchus mykiss) were infected by immersion and sampled for up to 14weeks post-infection. Yersinia ruckeri was cultured from the posterior kidney of more than 89% of fish up to 4weeks post-infection, but from 2% or fewer of fish sampled at later time points. In contrast, qPCR-based detection of the Y.ruckeri 16s rRNA gene in intestine and spleen extracts revealed a much higher rate of infection: at 14weeks post-infection Y.ruckeri was detected in nearly 50% of spleens and 15% of intestines. The difference between spleen and intestine is likely due at least in part to technical limitations of qPCR on intestinal DNA extracts; accordingly, we propose that qPCR of spleen DNA ought to be considered the preferred standard for detection of carriers of Y.ruckeri.

The bioactive compounds and microbial endophytes from brown seaweed as antibacterial for aquaculture disease management: A review

Brown seaweed contain bioactive compounds such as flavonoids, steroids, triterpenoids, alkaloids, saponins, tannins that have antimicrobial potential. The use of brown seaweed extract in several studies has reported that brown seaweed extract has a capability to inhibit the activity of bacteria such as S. aureus and Pseudomonas aeruginosa and Klebsiella pneumoniae bacteria, these bacteria are bacteria that attack aquatic organisms such as fish. Endophytic microbes associated with seaweed such as bacteria and fungi are thought to be able to produce the same bioactive compounds as their host, seaweeds. Several studies have also shown that the antibacterial activity of endophytic microbes can inhibit pathogenic bacteria. Most of results showed that the extract of brown seaweed could inhibit the pathogens ranged moderate to strong category.

Effect of oxytetracycline on the biosafety, gut microbial diversity, immune gene expression and withdrawal period in Pacific whiteleg shrimp, Penaeus vannamei

Aquaculture disease management has been one of the primary focuses of improved production and profitability. Oxytetracycline (OTC) is a broad-spectrum antibiotic approved for therapeutic applications in aquaculture. Though maximum residue levels, safety and withdrawal period is established for finfish and tiger shrimp (Penaeus monodon), similar information is scanty on Pacific whiteleg shrimp, Penaeus vannamei, farmed under the tropical climates of South Asia. In this study, P. vannamei was administered with OTC for 14 days at different doses, 2.25, 4.5, 9.0, 18.0 g kg−1. OTC administration at 4.5 g kg−1 feed dose or less caused no significant impact on the growth or survival of the shrimp during the study period. The residual concentration in shrimp muscle declined below 0.1 ppm in 96 h post-treatment and was undetected at 120 h post-treatment. There were no significant histological changes in hepatopancreas, antennal gland and hematopoietic tissue at the therapeutic dose (4.5 g kg−1 feed), while dose-dependent toxic changes were observed in the lymphoid organ. Therapeutic dose of OTC administration did not influence the relative expression of crustin, penaeidin, lysozyme, pro-phenol oxidase and superoxide dismutase. Dose-dependent reduction in gut microbial diversity was observed as revealed by denaturing gradient gel electrophoresis (DGGE). In all the treatments, however, the microbial diversity was restored 14 days post-cessation of OTC administration. The observed 50% inhibition of phytoplankton Arthrospira platensis and Chlorella vulgaris (68.17 and 78.18 mg L−1 OTC, respectively) and 50% immobilisation of copepods and rotifers (173.89 and 257.16 mg L−1 OTC, respectively) was significantly higher than the therapeutic dose. Oxygen consumption, ammonia excretion, feeding rate and ingestion rate of copepod was significantly reduced at and above 187.5 mg L−1 OTC, while rotifers showed no impact of OTC up to 750 mg L−1, which is higher than the recommended therapeutic dose. The study has indicated that 96 h of withdrawal period may be required for safe use of OTC at 4.5 g kg−1 feed for 14 days in Indian P. vannamei farming.

Endophytes From Algae, a Potential Source for New Biologically Active Metabolites for Disease Management in Aquaculture

Endophytes are microorganisms that live inside the plant tissue without causing external symptoms. All plants in nature harbor endophytes. Some endophytes produce and secrete biologically active compounds, known as secondary metabolites, which can help the host plant cope with bacterial, fungal, and other pest pathogens. Endophytes are isolated from aquatic plants and algae. Diseases are detrimental in the aquaculture industry where chemical pesticides and antibiotics are widely used in an attempt to cope with fish pathogens. However, the ability to prevent disease outbreaks in aquaculture is currently extremely limited. Here, we isolated 173 bacterial and fungal endophytes from 16 Mediterranean seaweed and 4 algae from fresh or thermo-mineral water. We found 88 endophytes (51%) with biological activity against four common aquaculture pathogens. Fifty endophytes (29%) caused mortality of at least one of these four pathogens. We identified 23 bioactive endophytes, 18 of which are from the Bacilli class. Our findings suggest that macroalgae from different aquatic environments can serve as a good source of potential biocontrol agents against aquaculture diseases. To the best of our knowledge, there are no published studies demonstrating the use of algal endophytes to control aquaculture diseases. Our study may lead to finding new molecules for use as novel environmentally friendly products that will solve one of the most challenging problems for the growing aquaculture industry: pathogens and pests.