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In this paper, based on the analysis of Pelteobagrus intestinal flora, from screening potential probiotic strains of common pathogens of freshwater fish have strong antagonism, and study its characteristics, while assessing its Feeding on the Growth, immune and intestinal flora diets, to provide a scientific basis for probiotic tie in yellow catfish feed. The main results are as follows: (1) the number of the gut of Pelteobagrus and their water flora and composition analysis. The results show that, each bowel in Pelteobagrus the number of aerobic and facultative anaerobic bacteria (value) were 5.27 ± 0.74,6.26 ± 0.36,7.56 ± 0.61. Anaerobic than aerobic and facultative anaerobes high number of 2-3 orders of magnitude, are dominant bifidobacteria (Bifidobacterium). Farming Waters of the number of bacteria (value) of 4.80 ± 0.73. The same yellow catfish intestinal aerobic and facultative anaerobic bacteria breeding waters advantages flora are Aeromonas (Aeromonas), Enterobacteriaceae (Enterobacteriaceae), Acinetobacter species (Acinetobacter). In addition, the results of research on the risk of the catfish intestinal flora bacterial hemorrhagic show a significant increase in the number of intestinal bacteria of diseased fish, the Aeromonas compared to healthy Pelteobagrus an increase of 18.3% -33.6%, bacterial species significantly reduced. (2) brain heart infusion medium (BHI) from the health of Pelteobagrus intestinal isolated 65 Bacillus Tablet o'clock screening 53 can inhibit common pathogens of freshwater fish (columnar addicted to fiber bacteria Cytophaga columnaris the Edwardsiella tarda Edwardsiella tarda, Aeromonas hydrophila Aeromonas bacteria Aeromonas hydrophila, mild Aeromonas of Aeromonas sobria E. coli antagonistic strains of Escherichia coli), inhibition zone diameter range of 6.9-20.5 (mm) . Stronger antibacterial activity of nine strains with Oxford cup method rescreening 3 antagonist, on six indicator bacteria have strong antagonistic. The API 50CHB identify them as Bacillus subtilis. Select F14 to further study its temperature tolerance, acidity tolerance, antibiotic sensitivity, metabolic crude extracts Antifungal Activity and survival in the feed. Show: strain F14 in 90 ℃ water bath for 5 min, the survival rate was 95.3%, the survival rate was 52.97% to 100 ° C water bath for 5min, 10min after survival rate was 8.26%; pH3.0-5.0 range, for 1h survival rate of more than 98%; survival for 2h can reach more than 87%; 15 drug susceptibility test results show that the eight kinds of drugs, F14 is very sensitive, more sensitive to the drugs, and three kinds the drug insensitive; F14 metabolic crude extract has strong antimicrobial effect. Pathogenic hydrophila Aeromonas crude extract for 2h, began a sharp decline in the number of bacteria, less than live bacteria has been detected up to 24 h. In addition, the F14 is sprayed on feed were stored at room temperature, 4 ° C and -20 ℃ conditions, 10d F14 survival rates were: 75.26%, 87.42% and 94.23% survival after 20d, respectively: 57.73 %, 77.53% and 87.63%, respectively. (3) the basic diet for the control group (A0), the period 60d feeding experiments farming systems, study of dietary 107cfu / g (A1), 108cfu / g (A2) and 109cfu / g (A3) Bacillus subtilis F14 Growth and immune and intestinal flora. The results showed that different concentrations of the F14 could improve the growth performance of catfish, the group A2 relative growth rate and specific growth rate is the highest (P lt; 0.05), feed conversion ratio was the lowest. F14 able to varying degrees to improve Pelteobagrus blood leukocytes phagocytic activity, lysozyme activity, serum myeloperoxidase (MPO) activity and serum complement activity. Compared with the control group, feeding F14 P. fulvidraco intestinal Aeromonas and Escherichia coli number was significantly lower (P lt; 0.05), the number of Bacillus with feeding time extension of a significant increase (P lt; 0.05). then stabilized at a higher level, the number of aerobic and facultative anaerobic bacteria also changed greatly. The results showed that the F14 can regulate intestinal flora, to activate Pelteobagrus immune defense system, increase resistance to disease, and to promote growth.
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