The Study Of Special Probiotics To Penaeus Vannamei

The use of probiotics in aquiculture draw people attention more and more in nowadays. This research firstly analyzed the compositon of intestinal microbe in Penaeus vannamei. After that,through the experiments of producing enzyme, hem-olysis and inhibiting the growing of bacterium, the safety of probiotics were also evaluated3potential probiotics strains were selected. We add single probitotic and mixed probities to feed to study the effect on the immune function,growing function and disease resistance in Penaeus vannamei.The purpose of this research is to provide theory basis for special probiotics of Penaeus vannamei.The achievements of this research are as fellows:1. The total aerobe and facultative anaerobe in the intestinal tract of healthy Penaeus vannamei reached4.43±0.11×107cfu/g.The dominant species in the intestinal tractwas Photobacterium(25.34%±4.55%).The secondary dominant species were Shewanella (25.34%±4.55%)Bacillus(14.55%±3.26%) Aeromonas(9.22%±2.28%) and Vibrio(9.22%±2.28%)2.3potential probiotics strains were selected through the experiments of producing enzyme,hemolysis and inhibiting the growing of bacterium.3potential probiotics strains were identified by molecular biology and Phylogenetic tree.The strain of D4belong to Shewanella haliotis,strain of D7belong to Bacillus cereus and strain of D15belong to Aeromonas bivalvium.3. Experiment was conducted to investgate the effects of feeding single probiotic (D4D7D15)and mixed probiotics to Penaeus vannamei on immune function,growing function and disease resistance.The Penaeus vannamei were fed single probiotic (D4D7D15)and mixed probiotics in diet at a concentration of～107cfu/g for28days. After the experiment trial,the Penaeus vannamei were challenged with vibrio harveyi and the body weight were also evaluated.The result of immune paramenters show that:compared with control,respiratory burst activity,ACP activity and lysozyme activity were increased significantly(P<0.05)at treatment of D15. Respiratory burst activity and ACP activity were increased significantly(P<0.05)at mixed group. The related genes expression of proPO and LGBP were significantly increased (P<0.05) at groups D4and D15.The related gene expression of PE-3a was significantly increased(P<0.05)at mix group.The result of toxicity experiment show that:afte28d feeding trial,group D15and mix can decreased mortality rate of Penaeus vannamei (P<0.05)after challenged with vibrio harveyi.The result of growing function show that:all the trial groups can increased the body weight of Penaeus vannamei significantly(P<0.05),compared with the control.