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Introduction to β-Glucan and Its Role in Aquaculture
In recent years, the aquaculture industry has been facing significant challenges due to various disease outbreaks affecting shrimp populations. The Pacific white shrimp (Penaeus vannamei), which constitutes a major portion of global shrimp production, is particularly vulnerable to bacterial and viral infections. To combat these issues, researchers have turned to natural immunostimulants like β-glucans, which are known to enhance the immune responses of aquatic animals. β-glucans are polysaccharides found in the cell walls of fungi, yeast, and some cereals, and they have been studied extensively for their immunomodulatory effects in aquaculture settings.
Recent studies have demonstrated that β-glucans can significantly improve shrimp health, enhance growth performance, and increase resistance to pathogens. The source and structure of β-glucans play a crucial role in their effectiveness as immunostimulants. This article focuses on a novel β-glucan derived from the insect fungus Ophiocordyceps dipterigena, exploring its potential benefits for Pacific white shrimp and the mechanisms by which it operates.
Mechanisms of β-Glucan in Immune System Activation
The immune system of shrimp is primarily composed of innate immune responses, which are crucial for defending against pathogens. β-glucans act as immunomodulators by enhancing these innate responses. When shrimp are fed diets supplemented with β-glucans, several immune-related mechanisms are activated, including:
- Recognition Proteins: β-glucans are recognized by specific receptors on immune cells, promoting the activation of immune pathways.
- Phagocytosis: The ingestion of pathogens by immune cells is enhanced, leading to improved clearance and survival rates.
- Prophenoloxidase System: This system plays a role in melanin synthesis and immune responses, which are crucial for combating infections.
- Cytokine Production: β-glucans stimulate the release of cytokines, which are signaling proteins that modulate the immune response.
Research has shown that the administration of β-glucans increases the expression of genes associated with immune functions, thereby bolstering the shrimp’s ability to respond to infections effectively. For instance, studies have indicated that shrimp fed with β-glucan from Ophiocordyceps dipterigena exhibited significantly improved immune levels and survival rates when challenged with pathogens like Vibrio harveyi.
Effects of β-Glucan on Growth Performance in Shrimp
In addition to enhancing immune responses, β-glucans have been shown to positively affect growth performance in shrimp. A study involving juvenile Penaeus vannamei fed diets supplemented with varying concentrations of β-glucan oligosaccharides (0%, 0.1%, and 0.4%) demonstrated that:
- Survival Rate: Shrimp receiving a higher concentration of β-glucan (0.4%) exhibited significantly greater survival rates compared to those in the control group.
- Specific Growth Rate (SGR): While the overall growth rate did not show significant differences, the immune enhancements contributed to better health status, which is critical in aquaculture.
- Feed Conversion Ratio (FCR): The efficiency of feed utilization also improved in shrimp given β-glucan, suggesting that these supplements can optimize feed resources.
The beneficial effects of β-glucan on growth performance are essential for aquaculture industries that strive to maximize yield and minimize the use of antibiotics.
Impact of β-Glucan on Microbiome Diversity and Composition
The gut microbiome of shrimp plays a vital role in nutrient absorption and overall health. β-glucan supplementation has been associated with alterations in the gut microbiota composition, which can further influence shrimp health. The administration of β-glucans has been shown to:
- Increase Microbiota Diversity: Shrimp fed with β-glucan supplements displayed a more diverse gut microbiome compared to controls. Enhanced diversity is linked to improved resilience against pathogens.
- Modulate Beneficial Bacteria: Specific bacterial taxa, such as Pseudoalteromonas and Vibrio, were significantly affected by β-glucan supplementation. For example, higher concentrations of β-glucan enriched the abundance of beneficial strains while suppressing potential pathogens.
- Promote Immune Function: A diverse microbiome supports the immune system by enhancing the production of short-chain fatty acids (SCFAs), which have anti-inflammatory properties.
The precise mechanisms through which β-glucans influence the microbiome are still under investigation, but the implications for shrimp health are promising, indicating a potential avenue for improving aquaculture practices.
Metabolomic Changes Induced by β-Glucan Supplementation
Metabolomics is a powerful tool for understanding the biochemical changes occurring in organisms in response to dietary interventions. In the case of shrimp fed β-glucans, several key metabolomic changes were noted:
- Enhanced Immune Metabolites: The presence of metabolites such as hydroquinone and nicotinic acid was found to increase in shrimp supplemented with β-glucan, indicating a boost in immune activity and homeostasis.
- Gut Health Indicators: Metabolomic profiling revealed alterations in metabolites related to gut health, suggesting that β-glucan supports the intestinal barrier and reduces inflammation.
- Energy Metabolism: Changes in metabolite profiles indicated improved energy utilization, which is critical for growth and immune function in shrimp.
By employing integrated -omics approaches, researchers can gain comprehensive insights into how β-glucans affect shrimp biology at molecular and systemic levels, thereby informing better dietary strategies in aquaculture.
Conclusion
The utilization of β-glucan derived from Ophiocordyceps dipterigena presents a promising strategy to enhance the health and performance of Pacific white shrimp (Penaeus vannamei). Through its immunomodulatory effects, β-glucan not only promotes higher survival rates and improved growth performance but also positively influences gut microbiome diversity and metabolomic profiles. This multifaceted approach to shrimp health could lead to reduced reliance on antibiotics and contribute to sustainable aquaculture practices.
References
- Uengwetwanit, T., Uawisetwathana, U., Angthong, P., Mongkhol, P., Metavee, P., Tala, S., Thepsuwan, T., Chaiyapechara, S., Prathumpai, W., & Rungrassamee, W. (2025). Investigating a novel β-glucan source to enhance disease resistance in Pacific white shrimp (Penaeus vannamei). Scientific Reports, 15, 1-13.
- Li, H. (2019). Beneficial effects of dietary β-glucan on growth and health status of Pacific white shrimp Litopenaeus vannamei at low salinity. Fish & Shellfish Immunology, 91, 315-324.
- Xu, B., & Yang, H. (2021). The influence of dietary β-1,3-glucan on growth performance, feed utilization, antioxidative, and immune status of Pacific white shrimp, Litopenaeus vannamei. Aquaculture Nutrition, 27, 1590-1601
- Amparyup, P., Charoensapsri, W., & Tassanakajon, A. (2013). Prophenoloxidase system and its role in shrimp immune responses against major pathogens. Fish & Shellfish Immunology, 34(4), 990-1001.
- Meena, D. K. (2022). β-glucan: an ideal immunostimulant in aquaculture (a review). Fish Physiology and Biochemistry, 39, 431-457
FAQ
What is β-glucan?
β-glucan is a polysaccharide found in the cell walls of fungi, yeast, and some cereals, known for its immune-enhancing properties.
How does β-glucan benefit shrimp?
β-glucan improves shrimp health by enhancing immune responses, increasing survival rates against pathogens, and potentially improving growth performance.
What is the role of the gut microbiome in shrimp health?
The gut microbiome aids in nutrient absorption, immune function, and overall health. β-glucan supplementation can positively influence gut microbiota diversity.
Why is it important to find alternatives to antibiotics in aquaculture?
The use of antibiotics can lead to resistance, making infections harder to treat. Natural immunostimulants like β-glucans provide a sustainable alternative to maintain shrimp health.
What further research is needed on β-glucans in aquaculture?
Future studies should focus on optimizing dosages, understanding specific microbial interactions, and exploring long-term effects on shrimp health and performance.
