Selection And Using Effect Of Probiotics For Shrimp Culturing

A total of 219 marine bacterial strains isolated from healthy shrimp and aquatic environment were tested for their inhibitory activities by using cross-streaking method,dot -inoculating method and scrip diffusion assay on 2216E plates. Six strains were selected by their inhibitory activities to four pathogenic indicating vibrios. Vibrio anguillarum,Vibrio parahaemolyticui,Vibrio campbelli and Vibrio natriegen were tested.Inhibitory activities of bacterial strain J-10 and it's extracellular products (ECP) against pathogenic Vibrio anguillarum was tested by viable bacteria counts, and influence facters were studied by plate diffusion assay.The results showed that J-10 indicated antagonistic action against Vibrio anguillarum after 24 h in the mixture culturing system.The bacterial counts decreased to a minimum at the third day,reducing the number of bacterium J-10 by 2Logio orders of magnitude than the first day,while the number of in the control group kept the number of the first from the second to the fifth day.This indicated that bacterial strain J-10 could strongly inhibit the growth in the mixture cultruing system.The ECP of bacterium J-10 could inhibit well the growth of Vibrio anguillarum, and it decreased the bacterial counts of Vibrio anguillarum in the test group to a minimum at 3 h and began to increase slowly after that, the bacterial number of control group kept increasing trend all the while.The ECP was sensitive to heat,not sensitive to various pH, not sensitive to proteinase K,the adding of Fe3+ could weaken the inhibitory activity of ECP.And bacterial strain J-10 was identified as Micrococcus sp.by morphological character, traditional physiological and biochemical method.Effect of temperature, salinity, pH, metal ion, different media volumes on the growth of bacterial strain J-10 were studied. The results showed that the optimal temperature condition is 24C~28C, salinity condition is 0-30, pH condition is7.5-9.0, and me bacterium can not grow in media with pH<5.0, the adding of KCl, CaC\2, NaCl, MgCl2, FeCl3 can not apparently promote the growth of bacterial strain J-10, rich soluble oxygen can increase the maximum biology volume.In the large-scale production, the optimal time of culturing is 24h~28h.Strsin J-10 was added to the feed of cultured shrimp and it's effect on phenoloxidase(PO),antibacterial activity(Ua),lysozyme activity(Ul) hemolysin activity, superoxide sismutase(SOD),peroxidase(POD)and protein concentration in the serum of Litopenaeus vannamei Boone was measured.All the indexes of the test group measured were better than the control group. Challenging with Vibrio parahaemolyticusi, the relative percent survived (RPS) value reached 40% .The results showed that probiotic J-10 could promote the non-special immune competence of Litopenaeus vannamei Boone.