TY - JOUR AU - Hasaninia, Abbas AU - Vahabzadeh Roudari, Habib AU - Khara, Hosein AU - Shenavar Masouleh, Alireza AU - Ahmadnezhad, Mohadeseh PY - 2022/12/11 Y2 - 2024/03/29 TI - Effect of dietary Lactococcus lactis and Bacillus subtilis on the innate immunity, intestinal microbiota, histometrical indices, and resistance against Aeromonas hydrophila in Oscar, Astronotus ocellatus Agassiz, 1831 JF - International Journal of Aquatic Biology JA - Intl. J. Aquat. Biol. VL - 10 IS - 6 SE - Articles DO - 10.22034/ijab.v10i6.1753 UR - https://ij-aquaticbiology.com/index.php/ijab/article/view/1753 SP - 438-450 AB - <p>This work aimed to investigate the effect of dietary <em>Lactococcus</em> <em>lactis</em> and <em>Bacillus subtilis</em> on the immune responses, intestinal microbiota, and resistance to pathogens of Oscar, <em>Astronotus ocellatus</em>. During 70 days trial, 300 juveniles (8.96±0.033 g) were fed diets enriched with <em>L. lactis</em> and <em>B. subtilis</em>. The treatments included 150, 300, 450 mg kg<sup>-1</sup> of dietary <em>L. lactis</em> (LL<sub>150</sub>, LL<sub>300</sub>, LL<sub>450</sub>); 150, 300, 450 mg kg<sup>-1</sup> of dietary <em>B. subtilis</em> (BS<sub>150</sub>, BS<sub>300</sub>, BS<sub>450</sub>); 150, 300, 450 mg kg<sup>-1</sup> of diet an equal mixture of <em>L. lactis</em> and <em>B. subtilis</em> (MIX<sub>150</sub>, MIX<sub>300</sub>, MIX<sub>450</sub>); and a non-supplemented control group. At the end of the rearing period, histological, immunological, and intestinal microbiota indices in treatments were investigated. To evaluate disease resistance, 15 fish in each treatment were infected in each treatment by <em>Aeromonas hydrophila</em>. The results showed that adding <em>B. subtilis</em> and <em>L. lactis</em>, particularly in MIX<sub>300</sub>, reduced the anaerobic heterotrophic bacterial microbiota and increased lactic acid bacteria (LAB) in fish. The highest white blood cell (WBC) level was recorded in the LL<sub>150 </sub>group. The lymphocytes in fish fed LL<sub>150</sub>, LL<sub>300</sub>, MIX<sub>150</sub>, and MIX<sub>300</sub> diets were changed and neutrophils of LL<sub>150</sub>, LL<sub>300</sub>, LL<sub>450</sub>, MIX<sub>300, </sub>and MIX<sub>450</sub> were significantly increased. Monocytes in fish fed MIX<sub>300</sub> and MIX<sub>450</sub> diets raised significantly. The IgM, ACH<sub>50</sub>, and lysozyme levels in fish-fed diets enriched by bacteria, especially in LL<sub>450</sub>, were significantly higher than the control treatment. The intestinal villi in LL<sub>450</sub>, BS<sub>150</sub>, and MIX<sub>450</sub> were significantly higher, showing lower damages than the other treatments. The survival rates of the infected fishes were higher in MIX<sub>150</sub> and MIX<sub>300 </sub>groups.</p> ER -