fa Biology & physiology Biology & physiology پژوهشي Orginal research papers <p>In this study, two main probiotics (<em>Lactobacillus plantarum</em> and <em>Lactobacillus delbrueckii </em>subsp<em>. bulgaricus</em>) were isolated from the intestine of <em>Tor grypus</em> and their effects on growth performance, gut microbial flora and digestive enzymes activities (i.e., &alpha;-amylase, lipase, trypsin, chymotrypsin, and alkaline phosphatase) of <em>Tor grypus</em> (Karaman, 1971) were determined. Juveniles of <em>T. grypus</em> (n=480, weighing 45&plusmn;10 g) were randomly divided into 4 equal&nbsp; groups (with 3 replications) and fed on diets containing 5&times;10⁷ cfu g^-1 of <em>L. plantarum</em> (G1), <em>L. bulgaricus</em> (G2), <em>L. casei </em>(G3) and a control diet (without probiotic) for 60 continuous days. Results showed that probiotic supplementations had generally significant effects on growth performance (<em>p<0.05</em>). The G2 group had the best effect on specific growth rate (SGR) and feed utilization efficiency in <em>T. grypus</em>. The digestive enzyme activities, on day 30 after feeding, significantly increased in G1 when compared with those in the control group (<em>p<0.05</em>). Significant changes in bacterial intestinal flora were observed in all probiotic groups compared with the control (<em>p<0.05</em>). Our results indicated that supplementation of isolated bacteria from the intestine of <em>T. grypus </em>(i.e., G2) can efficiently improve growth performance, intestinal microbiota and some digestive enzyme activities in juvenile <em>T. grypus</em>. Therefore, it can be isolated and used as a growth enhancer just like the commercial probiotics.</p> Tor grypus, Intestine lactobacilli, Growth performance, Digestive enzyme activity, Microbial flora. 296 317 http://jifro.ir/browse.php?a_code=A-10-792-7&slc_lang=fa&sid=1 T. Mohammadian tak.mohammadian@gamil.com 100319475328460020057 100319475328460020057 Yes M. Alishahi 100319475328460020058 100319475328460020058 No M.R. Tabandeh 100319475328460020059 100319475328460020059 No M. Ghorbanpoor 100319475328460020060 100319475328460020060 No D. Gharibi 100319475328460020061 100319475328460020061 No