Tilapia aquaculture faces escalating disease losses under intensive farming, motivating safe antibiotic alternatives. We evaluated the probiotic potential of Lacticaseibacillus paracasei AAHM-LP2301, a strain isolated from healthy tilapia during a disease outbreak. Whole-genome sequencing confirmed species identity and safety indicators (3.12 Mb; GC 46.4 %; 2892 CDS). Red tilapia were fed for 30 days with cells, cell-free supernatant (Cfs), or both, then maintained 30 days on a basal diet. Growth performance and brain, muscle, and liver growth hormone ( gh ) expression were unaffected at Day 30 and Day 60 ( P > 0.05). In contrast, antioxidant capacity improved broadly. During feeding, catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH) increased across multiple tissues compared with controls ( P < 0.05), with a CAT-centered carry-over at Day 60. Lipid peroxidation decreased by Day 60, malondialdehyde levels rebounded in controls but remained significantly lower in probiotic groups ( P < 0.05). Intestinal barrier and immune readiness were enhanced, with marked upregulation of tight-junction genes muc , zo1 , ocln , cldn , and immune genes nfκb , il1b , il6 , il8 , ifng , tnfa , hamp , lyz, ctl , c3 at both time points ( P < 0.05). Humoral responses increased, including lysozyme activity, bactericidal activity, and serum IgM. Challenge with Edwardsiella tarda demonstrated functional protection: survival rates were 70 % in Cell (relative percent survival 53.8 %) and 65 % in Cfs and Cell+Cfs (RPS 46.2 %), exceeding controls (35 % and 45 %; P < 0.05). Principal component and correlation analyses supported coordinated antioxidant and immune profiles distinguishing probiotic groups from controls. Overall, L. paracasei AAHM-LP2301 is a safe, multifunctional probiotic that strengthens mucosal barriers, enhances antioxidant defenses, and increases disease resistance without compromising growth, supporting resilience-focused tilapia aquaculture. • Genome sequencing verified the identity and biosafety of Lacticaseibacillus paracasei AAHM-LP2301. • Probiotic supplementation enhanced antioxidant defenses, lowering oxidative stress in tilapia tissues. • Tight junction integrity and immune-related gene expression were significantly upregulated. • Humoral immunity was strengthened, with elevated lysozyme activity, bactericidal capacity, and IgM levels. • Dietary supplementation improved tilapia survival following Edwardsiella tarda challenge.
Meachasompop et al. (Tue,) studied this question.