Immune response, gene expression, and intestinal microbial composition of Pacific white shrimp fed with multispecies synbiotic for the prevention of coinfection disease

Probiotic modulation of key immune macromolecules in shrimp

The rapid expansion of shrimp aquaculture has been accompanied by significant disease challenges, driving the need for innovative prevention strategies. Probiotics, which are live microorganisms that confer health benefits to the host, have shown promise in controlling diseases in aquatic environments. Shrimp rely on their innate immune system, including physical barriers, and cellular and humoral defenses, for protection against pathogens. Physical barriers include the exoskeleton and the digestive tract, while cellular defenses involve hemocytes that engage in encapsulation, phagocytosis, and nodulation. Humoral defenses include the prophenoloxidase (proPO) system, lectins, agglutinins, and antimicrobial peptides (AMPs). Recent studies suggest that shrimp innate immunity can exhibit immunological memory, primarily through the actions of phagocytic cells. This review explores the use of probiotics in shrimp aquaculture, with a focus on their interaction with the shrimp immune system and their potential role in probiotic selection, either through environmental adaptation or as feed additives. Probiotics that enhance shrimp immunity by boosting phagocytosis, modulating the proPO system, and interacting with key signaling pathways such as Toll, IMD, and JAK/STAT offer a promising means of improving disease resistance. Probiotics play a critical role in modulating the infection process, influencing pathogen virulence factors, and shaping host-pathogen interactions. Further research into emerging immune pathways in shrimp could deepen our understanding of crustacean immunity and its applications in aquaculture.

Dietary administration of yeast (Saccharomyces cerevisiae) hydrolysate from sugar byproducts promotes the growth, survival, immunity, microbial community and disease resistance to VP (AHPND) in Pacific white shrimp (Litopenaeus vannamei)

This study investigated the effects of yeast hydrolysate (YH) from sugar byproducts on various parameters in Pacific white shrimp (Litopenaeus vannamei). The study found no significant differences in water quality parameters across all treatment tanks, ensuring that the observed effects were not due to environmental variations. There were no significant differences in growth parameters between the control group and groups receiving YH at different dosages. However, the group given YH at 10.0 g/kg feed exhibited a notably higher survival rate and higher expression of growth-related genes (IGF-2 and RAP-2A) in various shrimp tissues. YH was associated with enhanced immune responses, including lysozyme activity, NBT dye reduction, bactericidal activity, and phagocytic activity. Notably, the 10.0 g/kg feed group displayed the highest phagocytic index, indicating a dose-dependent immune response. Expression of immune-related genes (ALF, LYZ, ProPO, and SOD) was upregulated in various shrimp tissues. This upregulation was particularly significant in the gills, hepatopancreas, intestine, and hemocytes. While total Vibrio counts remained consistent, a reduction in green Vibrio colonies was observed in the intestine of shrimp treated with YH. YH, especially at 5.0 and 10.0 g/kg feed dosages, significantly increased survival rates and RPS values in response to AHPND infection. The findings of this study suggest that incorporating additives derived from yeast byproducts with possible prebiotic properties obtained from sugar byproducts can lead to positive results in terms of enhancing growth performance, immunity, histological improvements, and resistance to V. parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND).

Recent progress in the use of purple non-sulfur bacteria as probiotics in aquaculture

The use of probiotics in aquaculture is widely recognized as an ecological and cost-effective approach to raising healthy, pathogen-tolerant aquatic animals, including fish and shrimp. In particular for shrimp, probiotics are viewed as a promising countermeasure to the recent severe damage to the shrimp industry by bacterial and viral pathogens. Purple non-sulfur bacteria (PNSB) are Gram-negative, non-pathogenic bacteria with wide application potential in agriculture, wastewater treatment, and bioenergy/biomaterials production. In aquaculture, lactic bacteria and Bacillus are the major probiotic bacteria used, but PNSB, like Rhodopseudomonas and Rhodobacter, are also used. In this review, we summarize the previous work on the use of PNSB in aquaculture, overview the previous studies on the stimulation of innate immunity of shrimp by various probiotic microorganisms, and also share our results in the probiotic performance of Rhodovulum sulfidophilum KKMI01, a marine PNSB, which showed a superior effect in promotion of growth and stimulation of immunity in shrimp at a quite low concentration of 1 × 10³ cfu (colony forming unit)/ml in rearing water.