Mini-review: Utilization of Sargassum and its role in the non-specific immune resistance of fish and shrimp against bacterial infections

Abstract

Bacterial infections are a major problem in fish farming, causing significant economic losses. Excessive use of antibiotics can lead to the risk of resistance and environmental pollution, making the use of safe and environmentally friendly natural antimicrobials crucial. Sargassum, a type of brown macroalgae, has the potential to act as a natural immunostimulant that can enhance fish's non-specific immune resistance to bacterial infections. Various species Sargassum, including S. kjellmanianum, S. muticum, S. polycystum, S. ilicifolium, and S. vulgaris, have been explored as a bioactive source through methods such as ethanol extraction, solvent fractionation, sequential extraction, phytochemical screening, and probiotic fermentation. In compound identification, phenolics, flavonoids, terpenoids, saponins, sulfated polysaccharides, and fucoidan have been found to be the dominant components. Administration through feed or seaweed supplements has been shown to increase immune gene expression (IL-1β, IL-8, TNF-α, IGF-1, LGBP, peroxinectin, prophenoloxidase, TLR, penaeid), leukocyte count, lysozyme activity, total complement, NBT, bactericidal activity, growth performance, and resistance to bacterial stress or challenge (Aeromonas hydrophila, Vibrio harveyi, Vibrio parahaemolyticus) in target species such as rainbow trout (Oncorhynchus mykiss), Asian seabass (Lates calcarifer), oscar fish (Astronotus ocellatus), common carp (Cyprinus carpio), yellow catfish (Pelteobagrus fulvidraco), and black tiger shrimp (Penaeus monodon). These findings indicate that Sargassum has great potential as a crucial feed immunostimulant to support the health and growth of fish and shrimp.

Keyword: aquaculture, bacterial infections, innate immunity, Sargassum