Effects of combined supplementation of Bacillus pumilus SE5 peptidoglycan and lipoteichoic acid on immune, antioxidant capacity, and intestinal morphology of Epinephelus coioides.

The experiment aimed to investigate the effects of peptidoglycan and lipoteichoic acid extracted from Bacillus pumilus SE5, when added individually and in combination, on the immune response, antioxidant capacity, and intestinal morphology of Epinephelus coioides. A total of 540 healthy groupers with an initial body weight of (14.69±0.04) g were randomly divided into six groups, with three replicates per group and 30 fish per replicate. The control group (CG group) was fed a basal diet, while the experimental groups were fed the basal diet supplemented with inactivated Bacillus pumilus SE5 (1.0 x 108 CFU/g, HIB group), peptidoglycan (52.86 mg/kg, PGN group), lipoteichoic acid (6.60 mg/kg, LTA group), and combined peptidoglycan and lipoteichoic acid (26.43 mg/kg + 3.30 mg/kg, PLA01 group; 52.86 mg/kg + 6.60 mg/kg, PLA02 group). The trial period was eight weeks. The results showed that the acid phosphatase (ACP) activity in the liver of Epinephelus coioides in the HIB and PLA01 groups was significantly higher than that in the CG and LTA groups (P<0.05). The intestinal superoxide dismutase (SOD) activity in the HIB group was significantly higher than that in the CG group (P<0.05). The malondialdehyde (MDA) content in the intestines of all experimental groups was significantly lower than that in the CG group (P<0.05). Except for the HIB and LTA groups, the villus height in the intestines of all experimental groups was significantly higher than that in the CG group (P<0.05), with the PLA01 group having the longest villi. The muscle layer thickness was greatest in the PLA02 group, and the muscle layer thickness in the PGN, PLA02 groups was significantly higher than that in the CG group (P<0.05). The study indicates that the combined addition of lipoteichoic acid and peptidoglycan from Bacillus pumilus SE5 has a better promoting effect on the immune efficiency, intestinal antioxidant capacity, and intestinal morphology of Epinephelus coioides than individual additions, and PLA01 group shows better potential. [ABSTRACT FROM AUTHOR]