Poly-β-Hydroxybutyrate Applications in Aquaculture Nutrition

Poly-β-hydroxybutyrate (PHB) is a biodegradable bacterial polymer that has emerged as a multifunctional feed additive in aquaculture. When incorporated into diets or delivered via enriched microbial biomass, PHB supports growth performance, modulates gut microbiota and enhances host defence mechanisms. Both immunostimulatory and antimicrobial modes of action have been described: PHB can prime innate immune pathways, promoting cellular and humoral responses, while its degradation product, 3-hydroxybutyrate, interferes with pathogen virulence. Applications span larval fish and shrimp culture to echinoderms and carnivorous species, with practical benefits including improved survival under disease challenge, better feed conversion and elevated levels of beneficial fatty acids. Recent advances also demonstrate sustainable production routes for PHB from aquaculture wastes, offering a circular-economy solution that addresses environmental and nutritional objectives across global aquaculture systems.

Research from Nature Portfolio

Recent studies have elucidated multiple protective modes of PHB in aquatic organisms. Early investigations demonstrated that dietary PHB induced heat shock protein 70 in gnotobiotic brine shrimp, leading to enhanced innate immune responses via activation of prophenoloxidase and transglutaminase pathways, which conferred protection against Vibrio pathogens. Further work revealed that PHB degrades in the gastrointestinal tract to release 3-hydroxybutyrate, a monomer that impairs Vibrio virulence by suppressing haemolysin, protease and motility, thus reducing bacterial pathogenicity without affecting growth. These findings highlight both immunostimulatory and anti-virulence mechanisms underlying PHB’s efficacy in disease control.

Poly-β-Hydroxybutyrate Applications in Aquaculture Nutrition publication trend

The graph below shows the total number of articles in poly-β-hydroxybutyrate applications in aquaculture nutrition across all publications each year (not limited to Nature Index journals).

Technical terms

Poly-β-hydroxybutyrate (PHB): A biodegradable polymer synthesised by bacteria, used as a feed additive with immunostimulatory and antimicrobial properties.

3-hydroxybutyrate (3HB): A monomeric degradation product of PHB that modulates pathogen virulence factors.

Innate immunity: The non-specific first-line defence in animals, involving cellular (e.g., phagocytes) and humoral (e.g., complement) responses.

Coelomocytes: Immune effector cells in echinoderms responsible for phagocytosis and respiratory burst.

Virulence factors: Molecules produced by pathogens (e.g., haemolysin, proteases) that facilitate infection and disease.

NF-κB signalling pathway: A conserved transcription factor pathway regulating immune gene expression in response to stress and infection.

References

1. Probing the protective mechanism of poly-ß-hydroxybutyrate against vibriosis by using gnotobiotic Artemia franciscana and Vibrio campbellii as host-pathogen model. Scientific Reports (2015).
2. Virulence-inhibitory activity of the degradation product 3-hydroxybutyrate explains the protective effect of poly-β-hydroxybutyrate against the major aquaculture pathogen Vibrio campbellii. Scientific Reports (2018).
3. Effects of Dietary Poly-β-Hydroxybutyrate Supplementation on the Growth, Non-specific Immunity, and Intestinal Microbiota of the Sea Cucumber Apostichopus japonicus. Frontiers in Marine Science (2022).
4. Effect of Amorphous Halomonas-PHB on Growth, Body Composition, Immune-Related Gene Expression and Vibrio anguillarum Resistance of Hybrid Grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatu ♂) Juveniles. Animals (2024).
5. An Eco-Friendly Conversion of Aquaculture Suspended Solid Wastes Into High-Quality Fish Food by Improving Poly-β-Hydroxybutyrate Production. Frontiers in Physiology (2022).