Screening And Application Of Probiotics From Intestinal Tract Of Channel Catfish

In order to find out the normal bacterial flora in the gastrointestinal tract of channel catfish (Ictalurus punctatus Rafinsque), aerobic and facultative anaerobic bacteria were quantitatively analyzed using the spread-plate method, and the separate strains were classified. The results showed that the number of bacteria in foregut, midgut and posterior intestine of channel catfish were 3.72×106cfu/g,4.32×106cfu/g and 16.25×106 cfu/g respectively. The main bacterial flora in foregut were alcaligenes, aeromonas and enterobacteriaceae; while in midgut and hindgut were alcaligenes and aeromonas.Effects of basic cultural components, main elements and inorganic ions on growth of BHI344 and BHI346 islolated from the gut of normally breeding channel catfish were conducted and optimized using orthogonal experiment method. Optimum formula for BHI344 strains:peptone 1.0%, beef anointed 0.1%, salt 0.5%, yeast anointed 0.5%, glucose 1.0%, ammonium sulfate 0.05%, MgSO4·7H2O 0.1 g/L, CuSO4·5H2O 0.15mg/L, MnSO4·H2O 1.5 mg/L, CoCl2·H2O 0.15 mg/L, optimum formula for BHI346 strains: peptone 1.0%, beef anointed 0.1%, salt 1.0%, yeast extract 0.5%, ammonium sulfate 0.05%, MgSO4·H2O 0.1 g/L, MnSO4·H2O 1.5 mg/L, CoC2l·H2O 0.15 mg/L, CaCl2 0.02 g/L. Through contrast test with optimum formula and Common nutritional broth (peptone 1.0%, beef broth anointed 0.3%, salt 0.5%), the yield of bacteria in optimized culture were effectively improved.In order to study the effect of BHI344 strain added in the feed on water purification, we add in feed with BHI344 continuous for 21 days, collect water sample regularly on the 7th,14th and 21th days respectively, and compared with the sample that didn't add with bacteria. Results showed that, test group could effectively reduce the ammonia nitrogen, BOD and COD values of aquaculture water. After 14 days culture with feed added bacteria, the survival rate, growth rate and the ability to environmental factor tolerance of fry of the channel catfish were significantly increased compared with the control group.In order to provide evidence for BHI344 which could be used as Microbial Ecological Agents, the effect of BHI344 on immune function of Ictalurus punctatus were studied by testing the phagocytic activity of leucocytes; determineing the lysozyme activity, the conversion rate of lymphocytes and observing and counting the lymphocyte of intestinal epithelium. Results:compared with the control group, the phagocytic activity of leucocytes, quantity lysozyme activity, the conversion rate of lymphocytes and the quantity of lymphocyte of intestinal epithelium in test group all increased, but not significantly different (t test, p>0.05). To sum up, the finding in this study provide the evidence for BHI344 which could be used as Microbial Ecological Agents.