Applied Research Of Bdellovibrio On The Culture Of Grass Carp

The paper is composed of three parts of tests. The first part aimed to clarify the effect of Bdellovibrio bacteriovorus on the water quality and bacterial community in the grass carp ponds, by one factor experiment. In the second part the effect of Bdellovibrio bacteriovorus on the growth and immunization of Ctenopharyngodon idellus was studied by feeding different dose of Bdellovibrio bacteriovorus. The effect of Bdellovibrio bacteriovorus on enzymes activities related to immunity in Ctenopharyngodon idellus was studied in the third part.The main results are shown as follows:1. The main water quality indexes of the ponds could be remarkably improved by use of Bdellovibrio bacteriovorus. The COD, NH₃-N, sulphide in experimental groups were significantly lower than those in the control (P<0.05) . The DO in experimental groups were significantly higher than the control (P<0.05) . There were no significant differences in pH between experimental groups and the control (P>0.05) . The total number of bacteria and pathogenic bacteria in the tanks exhibited significant decreases as the concentration of Bdellovibrio bacteriovorus increased.2. Accession of Bdellovibrio bacteriovorus in the feed could improve the growth of grass carp, and reduce the feed coefficient significantly. After 36 days the relative growth rate had been raised 32.6%. Meanwhile, the immune indexes were also affected to some extent. The immune organ index of the Thymus rose gradually, the immune organ index of the Head Kidney dropped after initial rise, and the number of NBT-positive cell increased gradually. The immunoresponse level of Ctenopharyngodon idellus was enhanced apparently after the inoculation with the vaccine. It was demonstrated that the suitable supplement dose was 0.5% (w/w) .3. Compared with control, on the 21^st day and the 42^nd day of trial, it was found that the activities of AKP in livers of grass carp were significantly promoted(P<0.05).While, the activities of AKP in serums increased gradually on the 21^st day, no significant differences were observed between control and experimental groups (P>0.05). However, on the 42^nd day, it was shown that there are significant differences between control and experimental groups (P<0.05). Contrasted with control, on the 21^st day and the 42^nd day, the activities of ACP in serums increased significantly (P<0.05) and the activities of ACP in livers were observed to have highly significant increase (P<0.01): The activities of ACP in serums and livers showed a little trend of ascend on the 21^st day and the 42^nd day...