Effects Of Intestinal Dominant Bacteria On The Immune Faction Of Common Carp, Cyprinus Carpio

Now most commercial probiotics used in aquaculture practices are of non-fish origin.The investigation about the effects of intestinal bacteria on the immune faction of fish anddeveloping of fish special probiotic is relatively less. Therefore, the study analysed thecomprosition of intestinal flora of common carp(Cyprinus carpio) and selected the intestinaldominant bacteria. Then3strains of intestinal dominant bacteria were selected after hemolyticassays and safety evaluation test. The effects of these three strains of bacteria on thenon-special immunity of carp were investigated during feeding trials. The purpose of thisresearch is to provide theory basis for special probiotics of common carp. The achievementsof this research are as fellows:1.The study investigated the composition of the intestinal autochthonous bacteria, andidentified360strains of intestinal autochthonous bacteria belonged to Vibrio, Flavobacterium,Shewanella, Aeromonas, Micrococcus, Pseudomonas and Acinetobacter.Additionally,Aeromonas and Vibrio, Flavobacterium were dominant bacteria.2.Three strains of intestinal dominant bacteria BA-1, BA-2and BA-3were selected afterhemolytic assays which was used to exclude potential pathogens. The safety of the selectedisolates that showed no probable pathogenic in hemolytic assay was evaluated. Then, theywere identified as Aeromonas veronii BA-1, Vibrio lentus BA-2, and Flavobacteriumsasangense BA-3by16S rDNA gene and biochemical tests.3.To reveal the effects of these three strains of bacteria on the innate immunity of carp,the lysozyme, complement C3, total serum protein, albumin and globulin levels, respiratoryburst activity, phagocytic activity by blood leucocytes and the expression of IL-1b,lysozyme-C, and TNF-α were exmined after feeding with seven different diets for up to28days. Also the survival of carp against Aeromonas hydrophila was challenged for14days.The carp were fed seven different diets: one control, three diets supplemented with1×108cell g-1of carp intestinal bateria BA-1(Group D-I), BA-2(Group D-II) and BA-3(GroupD-III), and three diets supplemented with extracellular products FA-1(Group E-I), FA-2(Group E-II) and FA-3(Group E-III) which were corresponding to the strains BA-1, BA-2,and BA-3, respectively, up to28days. For groups D-I, D-III, E-I and E-III, the innate immuneparameters of carp were significantly increased, the expression of three immune-related genes in blood was significantly up-regulated examined during7,14, and21days of feeding, and thesurvival rate was improved. The study indicates that the two isolated intestinal autochthonousbacteria A. veronii BA-1and F. sasangense BA-3could positively influence immune responseand enhance disease resistance of carp against A. hydrophila infection.Therefore, it can be concluded that intestinal dominant A. veronii BA-1and F.sasangense BA-3could positively influence immune response and enhance disease resistanceof carp, and could be developed as probiotics.