| Yellow cartfish(Pelteobagrus fulvidraco) was took as the experimental materials and focused on the intestinal microflora, then a strain of probiotic Bacillus Licheniformis HS140 was isolated and supplemented with appropriate amount in diets to fed yellow cartfish, the infulence of dietary B. licheniformis on the resistance of yellow cartfish were determined by intestinal bacterial and non-specific immune function.(1)The aerobic intestinal bacterial floral of yellow cartfish Pelteobagrus fulvidraco was investigated. The total number of bacteria in the foregut, midgut, and hindgut were 3.95×106cfu/g,1.56×107cfu/g,2.98×107cfu/g.121 bacterial strains were islolated form the yellow cartfish Pelteobagrus fulvidraco. The dominant bacteria were Aerornonas spp, Enterobacteriacea, Vibrio spp, Pseudomonas spp.12,9 and 7 taxonomic groups were identificated from the foregut, midgut and hindgut respectively. Those bacterial strains include Corynebacterium spp, Bacillus spp, Misrococcus spp, Staphulococcus spp, Enterobacteriacea, Pseudomonas spp, Alcaligenes spp, Vibrio spp, Aerornonas spp, Moraxella spp, Acinetobacter spp, Flavobacterium spp.(2) 121 baiteria strains isolated form intestinal tract of cultured Pelteobagrus fulvidraco were used for testing the zymogenicities of protease, lipase and amylase, the antagonistic against 5 kinds of common pathogenic bacterias and the antibiotic sensitivity. the toxicity of strain HS140 screened as potential probiotic for Pelteobagrus fulvidraco was evaluated, and HS140 was identified according to it's morphological, physiological and biochemical characteristics as well as homology analysis of 16S rRNA genes sequences. The results indicated that HS140 have high zymogenicities ability and inhibitory to Edwardsiella tarda, Aerononas sobria and Vibrio anguillarum. HS140 was resistant to ampicillin, sulfamethoxazole,Ⅵcefradine, but sensitive or medium sensitive to the other 13 kinds of antibiotics, such as fulgram, neomycin and so on. It was safe for Pelteobagrus fulvidraco when they were challenged by a high immersion concent ration of HS140 at 108cfu/mL. Morphology observation showed that HS140 was gram-positive, rod and motile. The results revealed that strain HS140 comprised sequences more related to B. licheniformis (99.3%) from partial 16S rRNA genes sequences. The identification showed that strain HS140 was B. licheniformis by the way of morphology, biochemistry characteristic and 16S rRNA genes sequence homology analysis.(3) A strain of B. licheniformis HS140 with high ectoenzyme-producing ability was screened from Pelteobagrus fulvidraco Intestine. The growth characters of HS140 and Tolerance of pH, bile salt and thermal were investigated. The results indicated that the optimum fermenting time of HS140 was 16 hours; HS140 had significant acid resistance, the survival counts of HS140 about 102cfu/mL could be detected when pH value was at 2 for 2 hour; the number of HS140 reduced with the increase of bile salt concentration, less than 104 cfu/mL number of HS140 was detected when more than 0.30% bile salt was added in culture medium for 2 hours; In addition, HS140 had Obvious thermal resistance, the number of HS140 can reach 5.6×106cfu/mL and 2.8×106 cfu/mL at 90℃and 100℃for 10 minutes. The study showed that HS140 have great development prospect in the Pelteobagrus fulvidraco microbial preparations for it's tolerance characteristics.(4) Pelteobagrus fulvidraco was fed with diets supplemented with different amount of B. licheniformis HS140.56 days after the inoculation, the infulence of dietary B. licheniformis on the resistance of yellow cartfish were determined by examing the variation of aerobic and facultative anaerobic bacterial quantity and composition of the predominant bacterias. The results showed that the numbers of the interstinal microflora of yellow cartfish increase to about 1×108 cfu/g after feeding B. licheniformis with HS140, the differences was not much evident among the groups. After feeding with B. licheniformis HS140 the percentage of aeromonas and enterobacteriaceae diclined and Bacilus increased as the feeding days inceasing.(5) Pelteobagrus fulvidraco was fed with diets supplemented with appopriate amount of B. licheniformis HS140.56 days after the inoculation, the infulence of dietary B. licheniformis on the resistance of Pelteobagrus fulvidraco were determined by examing their gained weigh, lysozyme activity, phagocytic activity, total protein, SGPT activity in serum and relative percent survival (RPS) by challenging with live A. hydrophi. The results showed the adding B. licheniformis into the diets can not only enhance the immune response and the resistance of Pelteobagrus fulvidraco to A.hydrophi, but also improve their liver function and promote their growth to some degree. The appropriate adding density of B. licheniformis was 5×10 cfu/g.
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