Co-encapsulation of Bacillus aryabhattai CKNJH11 with Algae-derived Polysaccharides Enhances Growth Performance and Immune Response in Asian Seabass (Lates calcarifer)

The application of Bacillus species as probiotics in aquaculture has been widely documented, showing notable benefits in growth performance, feed efficiency, and immune response. In this study, Bacillus aryabhattai CKNJH11, isolated from shrimp pond sediment, was evaluated for its probiotic potential through 16S rRNA sequencing and comprehensive in vitro assays. The strain exhibited strong probiotic traits, including high acid tolerance (survival at pH 2.0), bile salt resistance (up to 5% for 6 h), and significant inhibition of biofilm formation by Pseudomonas aeruginosa and Vibrio parahaemolyticus (> 50% reduction). Safety evaluations confirmed the absence of hemolytic activity and susceptibility to common antibiotics, supporting its suitability for aquaculture use. An eight-week feeding trial involving 120 barramundi ( Lates calcarifer ) fingerlings compared four dietary treatments: control (no probiotics), free spores, alginate-encapsulated spores, and spores co-encapsulated with sodium alginate and red seaweed polysaccharides. Fish receiving the co-encapsulated probiotic diet exhibited significantly enhanced growth (final body length: 8.05 ± 0.11 cm; weight: 60.67 ± 1.98 g) and improved survival. Immunological analyses showed reduced Vibrio spp. in the gastrointestinal tract, along with elevated white and red blood cell counts and hemoglobin levels, indicating enhanced immune status. These results suggest that co-encapsulation of B. aryabhattai CKNJH11 with algae-derived polysaccharides improves probiotic efficacy and stability, offering a promising approach to enhance growth, immunity, and productivity in aquaculture systems.