en Treatment stategies with herbal or others Treatment stategies with herbal or others پژوهشي Original research papers <span style="font-size:11pt"><span style="line-height:97%"><span style="font-family:Calibri,sans-serif"><span lang="TR" style="font-size:11.5pt"><span style="line-height:97%"><span new="" roman="" style="font-family:" times="">Potential of a host-associated probiotic, <i>Bacillus subtilis</i>, was successfully screened from 6 isolates from the intestines of healthy rainbow trout (<a name="_Hlk176756749"><i>O. mykiss</i></a>) based on multiple probiotic characteristics in vitro assays, such as, hemolytic activity, biofilm formation, extracellular enzyme activity, inhibitory activity against pathogens, Physicochemical tolerance to gastrointestinal stress, cell surface hydrophobicity, autoaggregation, and antibiotic susceptibility. A total of 450 <i>O. mykiss</i> fingerlings were randomly distributed in three groups (one control and two probiotic-treated groups in triplicate) and fed with the basal (the control) and <i>B. subtilis</i>&ndash;supplemented diets (at a concentration of 5&times;10⁷ and 10⁸cell/mL <i>B. subtilis</i>,</span></span></span> <span lang="TR" style="font-size:11.5pt"><span style="line-height:97%"><span new="" roman="" style="font-family:" times="">over a period of 60 days. </span></span></span></span></span></span><br> <span style="font-size:11pt"><span style="font-family:Calibri,sans-serif"><span lang="TR" style="font-size:11.5pt"><span new="" roman="" style="font-family:" times="">After eight weeks of feeding trial revealed that dietary supplementation of <i>B. subtilis </i>6 at all two concentrations (5&times;10⁷ and 10⁸cell/mL of <i>B. subtilis</i>)</span></span> <span lang="TR" style="font-size:11.5pt"><span new="" roman="" style="font-family:" times="">immunological responses, biochemical parameters, antioxidant parameter and immune-relevant gene expression (interleukin 1&beta; (<i>IL-1&beta;</i>), <i>HSP70</i> and <i>TGF</i>-<i>&beta;</i>))) relevant to immunity were analyzed on the 30th, and 60th day post-feeding. After the 60-day feeding period, a significant (<i>p</i><0.05) enhancement in some immune-biochemical response and immune gene expression was evident. Serum AST, ALT levels exhibited a significant (<i>p</i><0.05) decrease. The inclusion of <i>B. subtilis </i>in the diets led to a substantial (<i>p</i><0.05) increase in the survival of <i>A. hydrophila</i>&ndash;challenged <i>O. mykiss</i>, thereby highlighting the potential of <i>B. subtilis </i>as a beneficial probiotic for aquaculture in short-time period.</span></span></span></span> Probiotic, Bacillus subtilis, Rainbow trout, Disease resistance 76 110 http://ijaah.ir/browse.php?a_code=A-10-415-1&slc_lang=en&sid=1 M. Bashiri m.bashiri1369@gmail.com 10031947532846003183 10031947532846003183 No 1 Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Iran M. Soltani msoltani@ut.ac.ir 10031947532846003184 10031947532846003184 Yes 1 Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Iran E. Pirali Kheirabadi pirali@sku.ac.ir 10031947532846003185 10031947532846003185 No 3Department of Fisheries, Faculty of Natural Resources, Shahrekord University, Shahrekord Province, Iran S.S. Mirzargar zargarm@ut.ac.ir 10031947532846003186 10031947532846003186 No 1 Department of Aquatic Animal Health, Faculty of Veterinary Medicine, University of Tehran, Iran S. Shafiei sshafiei@sku.ac.ir 10031947532846003187 10031947532846003187 No 4Department of Food hygiene, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord Province, Iran H. Momeni momenihosseindvm@gmail.com 10031947532846003188 10031947532846003188 No 5Aquatic Animal Health Unit, Department of Veterinary Medicine, Iran Veterinary Oragansiation, Shahrekord Province, Iran