In recent years, postbiotics have gained popularity as a key component for gut and overall health. If terms like probiotics, prebiotics, and synbiotics are already familiar to you, it’s time to explore the fourth piece: postbiotics.
This article will delve into what postbiotics are, their benefits for the health and nutrition of aquaculture species, practical examples, and their potential and challenges in aquaculture feeding.
What are postbiotics?
Postbiotics, also known as post-biotics, are bioactive compounds produced when probiotic microorganisms metabolize fibers or nutrients in the gut. These compounds include short-chain fatty acids, enzymes, antimicrobial peptides, vitamins, and polysaccharides.
The International Scientific Association of Probiotics and Prebiotics (ISAPP) defines postbiotics as: “a preparation of inanimate microorganisms and/or their components that confers a health benefit to the host” (Salminen et al., 2021).
Vinderola et al., (2022) highlight some key points about the definition of postbiotics:
- Inanimate: Postbiotics are derived from microorganisms that are no longer alive, or that are dead or inactivated.
- Components: Post-biotics may include intact microbial cells, structural fragments of microbes such as cell walls, and/or substances produced by microbes such as metabolites, proteins, or peptides.
- Health Benefit: To be considered a postbiotic, the preparation must demonstrate a health benefit for the host.
- Defined Microorganism: A post-biotic must be derived from a well-defined microorganism or combination of microorganisms with known genomic sequences, prepared through a delineated technological process for biomass production and inactivation that can be reproduced.
Unlike probiotics, which are live microorganisms, postbiotics are not organisms but the beneficial byproducts they leave behind.
Prebiotic vs probiotic vs synbiotic vs postbiotic vs paraprobiotic
By now, you might be confused with so many terms like prebiotics, probiotics, synbiotics, paraprobiotics, and postbiotics. The following table provides a comparison of these products.
Comparative table: Functional microbial additives in aquaculture nutrition.
| Category | Main Benefits | Limitations/Considerations | Specific Evidence |
| Probiotics | – Modulate immune function by increasing hemocytes. – Inhibit pathogens through biochemical compounds. – Combination of strains has a synergistic effect. | Non-significant results in some studies due to variation in strain, dosage, and treatment duration. | Secretion of bacteriocins, antibiotics, enzymes, among others. |
| Prebiotics | – Promote beneficial intestinal bacteria. – Improve nutrient and protein absorption. – Increase cells in the hepatopancreas. – Enhance immunity and overall health. | – Effectiveness influenced by host factors and culture conditions. – Less effective in improving growth. – Associated costs. | – Fructooligosaccharides (FOS) increase cells in the hepatopancreas. – Inulin enhances immunity and survival. |
| Synbiotics | – Synergistic effect between probiotics and prebiotics. – Boost immune function. – Improve resistance to oxidative stress. | – Require preliminary in vitro and in vivo studies to select optimal combinations. | – Increase hemocytes, PO, PA, and expression of antioxidant genes. |
| Paraprobiotics | – Modulate gut microbiota. – Promote beneficial bacteria. – Improve immune parameters. – Protect against salinity stress. | – Inactivation techniques must preserve strain benefits. – Associated production and standardization costs. | – Improve hemocyte counts and immune parameters. |
| Postbiotics | – Soluble factors that mimic probiotic effects. – Include bacteriocins, enzymes, peptides, organic acids, and vitamins. | – Mechanisms of action not fully understood. – Economic viability of large-scale production. | – Improve water quality and host health. |
Summary of Differences:
- Probiotics: Live microorganisms that benefit health.
- Prebiotics: Substrates that promote the growth of beneficial bacteria in the gut.
- Synbiotics: Combination of probiotics and prebiotics that act synergistically.
- Postbiotics: Non-viable microorganisms, cellular components, and/or metabolites that have beneficial effects on health.
- Paraprobiotics: Inactivated microorganisms or cellular fragments with health benefits.
Benefits of postbiotics in aquaculture
According to Liu et al., (2023) and Tao et al., (2024), postbiotics offer the following promising applications in aquaculture:
Enhancement of growth performance
Postbiotics can significantly improve the growth of various aquatic species. For example:
- Supplementation with Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) has been shown to enhance growth in juvenile black seabream (Acanthopagrus schlegelii).
- Growth improvements have also been observed in oriental river prawns (Macrobrachium nipponense), shrimp (Litopenaeus vannamei), and striped catfish (Pangasianodon hypophthalmus).
- The inclusion of HK L-137 postbiotics in the diet of bighead catfish (Clarias macrocephalus) resulted in significant increases in growth rate, protein efficiency rate, and feed conversion rate.
Disease resistance
Postbiotics strengthen the immune system of aquatic animals, enhancing their resistance to infectious diseases. Their administration can modulate immune responses, reduce disease outbreaks, and improve overall production efficiency.
Gut health improvement
Postbiotics can modulate the gastrointestinal microbiota, promoting a healthy gut balance. Studies have shown:
- Improved intestinal mucosa maturation.
- Strengthened mechanical barriers.
- Modulation of gut microbiota in aquatic species.
For instance:
- In zebrafish (Danio rerio), postbiotic administration enhanced microbiota homeostasis and reduced lipid metabolism disorders.
- In common carp (Cyprinus carpio), postbiotics increased the expression of genes encoding antioxidants and immune factors, improving intestinal integrity.
Improved nutrient utilization
By enhancing gastrointestinal tract health, postbiotics facilitate better digestion and nutrient absorption, leading to more efficient growth.
Environmental adaptability
Postbiotics help mitigate stress responses caused by adverse environmental conditions, such as high stocking density, hypoxia, and reduced salinity. For example:
- In Nile tilapia (Oreochromis niloticus), HK L-137 postbiotics significantly reduced cortisol secretion, alleviating stress induced by ammonium chloride exposure.
- Supplementation with L. plantarum improved fish tolerance to specific conditions.
Pathogen resistance
Postbiotics enhance host defenses against pathogens (Ang et al., 2020), improving survival rates after bacterial infections. This effect is primarily due to immunological stimulation. Sudhakaran et al., (2022) suggests that postbiotics can serve as an alternative to antibiotics.
Types of postbiotics in aquaculture
The studies by Ang et al. (2020) and Sudhakaran et al. (2022) highlight various categories of postbiotics and their applications in aquaculture:
Short-Chain fatty acids (SCFAs)
SCFAs, such as propionic acid and butyric acid, have been shown to modulate gut microbiota and protect hosts from infectious diseases. These acids, produced by bacteria like Propionibacterium and Clostridium tyrobutyricum, stimulate immune responses in various aquatic species, including shrimp, fish, and carp. For example, butyrate salts have been observed to provide protection against morbidity caused by pathogens such as Aeromonas hydrophila, Vibrio alginolyticus, and Photobacterium damselae ssp. piscicida.
Peptides (Bacteriocins)
Bacteriocins, antimicrobial proteins produced by bacteria, have the potential to replace antibiotics in treating aquatic diseases. These proteins are primarily active against closely related bacterial species, reducing the risk of developing antibiotic-resistant bacteria. Furthermore, bacteriocins can be digested by proteolytic enzymes in the digestive tract, leaving no residues in aquaculture feed.
Lal et al., (2023) reported that bacteriocins from postbiotics produced by two strains of Lactobacillus plantarum (GS12 and GS13) showed antibacterial activity against fish pathogens.
Exopolysaccharides (EPS)
EPS are polymers secreted into the external environment, exhibiting antimicrobial and anti-biofilm properties. These compounds can reduce the risk of pathogenic infections in aquaculture animals. For example:
- EPS from Bacillus cereus and Brachybacterium sp. have shown antimicrobial properties.
- EPS from Bacillus licheniformis and Pseudomonas stutzeri possess anti-biofilm properties.
Vitamins
Vitamin C (ascorbic acid) is a vital cofactor for biological processes and is used as an immunostimulant in aquaculture. It has been shown to enhance immune responses and increase resistance to infectious diseases in various aquaculture species (Kumar and Ravi, 2025).
Peptidoglycan (PG)
PG, a polymer of sugars and amino acids, also acts as an immunostimulant in aquaculture. It has been tested in sea cucumbers, Japanese flounder, and rainbow trout, improving immune responses and providing protection against pathogens.
Lipopolysaccharides (LPS)
LPS, molecules composed of lipids and polysaccharides, have been used as immunostimulants in various aquatic species. They have been shown to enhance immune responses and increase survival rates during infections.
Outer membrane proteins (OMP)
Outer membrane proteins (OMPs) are commonly used as vaccines in aquaculture. They have been demonstrated to stimulate immune responses, reduce bacterial loads, and decrease mortality. Successful polyvalent vaccines have been developed using OMPs from various pathogens.
Teichoic acids
Teichoic acids, a bacterial copolymer, show potential as vaccines, with antibodies demonstrating opsonization against Gram-positive species.
Methods of postbiotic preparation
The preparation of postbiotics involves a series of processes designed to inactivate microorganisms while preserving or extracting beneficial components. The methods vary depending on the type of postbiotic being produced (inactivated cells, cell-free extracts, metabolites) and the characteristics of the microbial strain used. Below is a summary of the main preparation methods:
Microbial inactivation methods
The primary objective of these methods is to eliminate the viability of microorganisms while preserving their bioactive components.
Thermal treatment
This is the most common method for inactivating microbial cells. It involves applying heat at a specific temperature for a set duration. The temperature and duration vary depending on the strain and the desired inactivation goal.
For instance:
- A water bath at 60°C for 30 minutes or 80°C for 1 hour.
- Heat treatment at 65°C for 30 minutes.
- Pasteurization at 70°C for 30 minutes.
Thermal treatment can result in the release of metabolites and cellular components into the surrounding medium.
Sonication (Ultrasound)
This method uses high-frequency sound waves to disrupt microbial cells. It serves as an alternative to thermal treatment and can facilitate the release of intracellular components. However, this method may affect the composition and efficacy of postbiotics.
Other Inactivation Methods
- Ionizing radiation: Uses radiation to inactivate microorganisms.
- UV irradiation: Employs ultraviolet light to damage the genetic material of microorganisms.
- High-pressure treatment: Uses hydrostatic pressure to inactivate cells.
Preparation of cell-free extracts (CE)
After inactivation, additional steps can be taken to obtain cell-free extracts:
Centrifugation
This method separates inactivated cells (pellet) from the supernatant containing soluble components (cell-free extract). For example, centrifugation at 4500 rpm for 10 minutes.
Filtration
Filtration removes solid particles to produce a purer cell-free extract.
Cell lysis
Mechanical, chemical, or enzymatic methods can be used to break cells and release intracellular components. For instance, alkaline lysis can be employed after thermal treatment.
Concentration and purification
Extracts can be concentrated using rotary evaporation or freeze-drying. Techniques such as dialysis and column chromatography can be used to purify the components of interest.
Microbial metabolite extraction
Metabolites can be obtained from the supernatant after microbial culture and inactivation.
Solvent extraction
Organic solvents are used to separate metabolites from the aqueous medium.
Chromatography
Various types of chromatography are employed to separate and identify specific metabolites.
Mass Spectrometry
When combined with chromatography, mass spectrometry allows classification and characterization of metabolites, such as fatty acids, glycerolipids, purines, and oligosaccharides.
Additional considerations
Culture medium
The medium used to grow microorganisms influences the composition and quantity of the products and metabolites obtained.
Microbial strain
The selection of the microbial strain is a key factor in the efficacy of the postbiotics produced. Not all probiotic strains are equally suitable for postbiotic production.
Fermentation process
The conditions of the fermentation process, including time and temperature, affect the production of postbiotics.
Standardization
The lack of standardized methods for evaluating postbiotics makes it challenging to compare results.
The preparation of postbiotics involves the inactivation of microorganisms, extraction of cellular components, and the acquisition of bioactive metabolites. Commonly used methods include thermal treatment, sonication, centrifugation, and filtration. The choice of preparation methods is critical to obtaining postbiotics with the desired composition and efficacy for their application in aquaculture.
Examples of Postbiotic Use in Aquatic Species
Tilapia
Quintanilla-Pineda et al., (2023) used Nile tilapia as a source of bacteria to investigate postbiotics with antimicrobial activity against fish pathogens. They found that Weissella cibaria produced postbiotics with great potential to inhibit the growth of Aeromonas salmonicida subsp. salmonicida.
Carp
Yu et al., (2023) reported that supplementing the diet of common carp (Cyprinus carpio) fed a high-fat diet (HFD) with postbiotics (SWFC) improved intestinal health and modulated the fish’s gut microbiota.
Rainbow trout
Mora-Sánchez et al., (2020) demonstrated that a postbiotic derived from lactic acid bacteria could modify the gut microbiota of rainbow trout, increase its diversity, and provide protection against lactococcosis.
Similarly, Quintanilla-Pineda et al., (2024) reported that Weissella cibaria produced postbiotics (CECT 30731 and CECT 30732) that improved gut microbiota and significantly enhanced the survival rate of rainbow trout (Oncorhynchus mykiss) when challenged with an experimental Yersinia ruckeri infection (the causative agent of Enteric Redmouth Disease).
Marine shrimp
Postbiotics can exhibit inhibitory activity against common shrimp pathogens. For instance, Hui et al., (2022) reported that cell-free supernatants from Lactobacillus plantarum fermentation cultures showed activity against Vibrio parahaemolyticus. Meanwhile, cell-free supernatants from Bacillus subtilis exhibited hemolytic activity against V. harveyi.
Vega-Carranza et al., (2025) reported that adding synbiotics and postbiotics to the diet of white shrimp (Litopenaeus vannamei) increased survival rates, modulated immune responses, and improved gut microbiota.
Limitations of postbiotics
Despite the promising potential of postbiotics in various applications, there are limitations and challenges that must be addressed to ensure their efficacy and large-scale viability. These challenges can be grouped into several key areas based on scientific literature:
Limited understanding of mechanisms of action
One major challenge is the lack of comprehensive understanding of how postbiotics work. While some mechanisms, such as immune modulation and gut barrier improvement, have been identified, the complexity of interactions between postbiotics and hosts requires further investigation.
Identifying and validating the specific bioactive components responsible for the observed benefits is essential. Additionally, the diversity of substances in postbiotics makes it difficult to determine which specific components produce the effects observed.
Variability and standardization
The composition and efficacy of postbiotics can vary significantly depending on the microbial strain used, preparation methods, and environmental conditions.
At a commercial level, postbiotics are less available compared to probiotics and prebiotics (Sudhakaran et al., 2022). Moreover, the lack of standardized methods for producing and evaluating postbiotics complicates comparisons across studies and products. Determining the optimal dosage for different species and conditions remains a significant challenge.
Availability and cost
Postbiotics are not as widely available commercially as probiotics and prebiotics. Large-scale production of postbiotics can be costly, potentially limiting their commercial application. Currently, most postbiotics are heat-inactivated probiotics, which restricts the diversity of available products.
Stability and shelf life
Although postbiotics are generally more stable than live probiotics, further research is needed to assess their stability in vitro and in vivo. Understanding how storage and processing conditions affect postbiotic shelf life and efficacy is critical. Studies are also required to explore how postbiotics interact with the host environment.
Safety and regulation
Rigorous safety assessments are essential to ensure that postbiotics pose no health risks to consumers or the environment. Establishing clear regulatory frameworks for the production and commercialization of postbiotics is crucial.
Limited research in some areas
Research on postbiotics in aquaculture is still in its early stages compared to fields like human health. More studies are needed to explore the potential of postbiotics in various aquatic species and their effects on disease control. Additionally, research on the interactions between postbiotics and other animal feed additives remains limited.
Industrial scaling
Most postbiotic research has been conducted at the laboratory scale. Scaling up production to an industrial level is necessary to evaluate their economic feasibility for commercial operations.
Conclusion
Although research on postbiotics is still developing, these compounds show significant promise as alternatives to probiotics and antibiotics in various fields, especially aquaculture.
Postbiotics represent a new frontier in aquaculture nutrition. From enhancing digestion to strengthening immune systems, these compounds offer natural and effective solutions for the health of aquatic species. Incorporating postbiotics through fermented foods or supplements can be a straightforward and powerful strategy.
References
Ang, C. Y., Sano, M., Dan, S., Leelakriangsak, M., & Lal, T. M. (2020). Postbiotics applications as infectious disease control agent in aquaculture. Biocontrol science, 25(1), 1-7.
Hui Goh, J. X., Teng-Hern Tan, L., Woan-Fei Law, J., Ser, L., Khaw, Y., Letchumanan, V., Lee, H., & Goh, H. (2022). Harnessing the potentialities of probiotics, prebiotics, synbiotics, paraprobiotics, and postbiotics for shrimp farming. Reviews in Aquaculture, 14(3), 1478-1557. https://doi.org/10.1111/raq.12659
Kumar, A., GR, S. K., & Ravi, L. (2025). Postbiotics metabolites in aquaculture. Postbiotics, 543-552.
Lal, M. T. M., Al A, S., & Motohiko, S. (2023). In Vitro Antibacterial Effect of Lactobacillus plantarum Postbiotics Against Fish Bacterial Pathogens. Journal of Survey in Fisheries Sciences, 2813-2819.
Liu, C., Ma, N., Feng, Y., Zhou, M., Li, H., Zhang, X., & Ma, X. (2023). From probiotics to postbiotics: Concepts and applications. Animal Research and One Health, 1(1), 92-114. https://doi.org/10.1002/aro2.7
Mora-Sánchez, B., Balcázar, J. L., & Pérez-Sánchez, T. (2020). Effect of a novel postbiotic containing lactic acid bacteria on the intestinal microbiota and disease resistance of rainbow trout (Oncorhynchus mykiss). Biotechnology Letters, 42, 1957-1962.
Quintanilla-Pineda, M., Achou, C. G., Díaz, J., Gutiérrez-Falcon, A., Bravo, M., Herrera-Muñoz, J. I., Peña-Navarro, N., Alvarado, C., Ibañez, F. C., & Marzo, F. (2023). In Vitro Evaluation of Postbiotics Produced from Bacterial Isolates Obtained from Rainbow Trout and Nile Tilapia against the Pathogens Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida. Foods, 12(4), 861. https://doi.org/10.3390/foods12040861
Quintanilla-Pineda, M., Ibañez, F. C., Garrote-Achou, C., & Marzo, F. (2024). A Novel Postbiotic Product Based on Weissella cibaria for Enhancing Disease Resistance in Rainbow Trout: Aquaculture Application. Animals, 14(5), 744. https://doi.org/10.3390/ani14050744
Salminen, S., Collado, M.C., Endo, A. et al. The International Scientific Association of Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of postbiotics. Nat Rev Gastroenterol Hepatol 18, 649–667 (2021). https://doi.org/10.1038/s41575-021-00440-6
Sudhakaran, G., Guru, A., Haridevamuthu, B., Murugan, R., Arshad, A., & Arockiaraj, J. (2022). Molecular properties of postbiotics and their role in controlling aquaculture diseases. Aquaculture Research, 53(9), 3257-3273. https://doi.org/10.1111/are.15846
Tao, L., Lu, H., Xiong, J., Zhang, L., Sun, W., & Shan, X. (2024). The application and potential of postbiotics as sustainable feed additives in aquaculture. Aquaculture, 592, 741237. https://doi.org/10.1016/j.aquaculture.2024.741237
Vega-Carranza, A. S., Escamilla-Montes, R., Luna-González, A., Fierro-Coronado, J. A., Diarte-Plata, G., & García-Gutiérrez, C. (2024). Survival, immune response, and gut microbiota in Litopenaeus vannamei fed with synbiotics and postbiotics and challenged with Vibrio parahaemolyticus. Aquaculture International, 32(1), 361-381.
Vinderola, G., Sanders, M. E., & Salminen, S. (2022). The concept of postbiotics. Foods, 11(8), 1077.
Yu, Z., Hao, Q., Liu, S., Zhang, Q., Chen, X., Li, S., Ran, C., Yang, Y., Teame, T., Zhang, Z., & Zhou, Z. (2023). The positive effects of postbiotic (SWF concentration®) supplemented diet on skin mucus, liver, gut health, the structure and function of gut microbiota of common carp (Cyprinus carpio) fed with high-fat diet. Fish & Shellfish Immunology, 135, 108681. https://doi.org/10.1016/j.fsi.2023.108681
