Comparative evaluation of biofloc-derived probiotics on growth performance, immune response, and intestinal microbiota modulation in Penaeus vannamei

This study aimed to evaluate the effects of biofloc-derived probiotic applications on growth performance, immunity, and intestinal microbiota profiles in biofloc-reared whiteleg shrimp ( Penaeus vannamei ). Three biofloc-derived probiotics, 1AP ( Tenacibaculum discolor ), 2AP ( Acinetobacter radioresistens ), and 1UP ( Vibrio tubiashii ), were used, each exhibiting beneficial digestive enzyme activities, including amylase, protease, and lipase. Shrimp (initial weight, 0.08 ± 0.01 g) were reared for 30 days in 60 × 40 × 30 cm 3 aquaria containing 30 L of water at a stocking density of 1000 PL m −3 . The experimental design included three probiotic treatments (1AP, 2AP, and 1UP) and a control with no probiotic supplementation. Probiotics were administered daily to the treatment groups at a concentration of 10 5 colony-forming units (CFU)/mL. Probiotic supplementation significantly increased final body weight (0.92 ± 0.12–1.68 ± 0.12 g) and specific growth rate (SGR) (8.42% ± 0.29–10.39% ± 0.14%) and significantly reduced the feed conversion ratio (FCR) (from 1.25 ± 0.07–1.02 ± 0.05) compared with the control ( P < 0.05). In addition, probiotic treatments significantly increased immune parameters, including total hemocyte count, phagocytic activity, phenoloxidase activity, and respiratory burst activity ( P < 0.05). The 2AP treatment substantially increased intestinal microbiota diversity and the number of unique operational taxonomic units (OTUs). Activities of the digestive enzymes amylase, protease, and lipase were higher, whereas Vibrio abundance was lower in probiotic-treated groups than in the control ( P < 0.05). Probiotic supplementation in the biofloc system also improved intestinal morphology. Overall, these findings indicate that biofloc-derived probiotics enhance growth performance, immune response, and intestinal microbiota diversity in shrimp, with 2AP ( A. radioresistens ) showing the greatest efficacy. • Biofloc-derived probiotics enhanced shrimp growth and feed efficiency. • Biofloc with Acinetobacter radioresistens improves the morphology and enzyme activity of gut shrimp. • Biofloc with Acinetobacte r radioresistens boosted gut microbiota diversity and unique OTUs. • Probiotics reduced Vibrio abundance, including pathogenic V. parahaemolyticus