EFFECTS OF THE IMMOBILIZED MICROALGAE ON THE QUANTITY DYNAMICS OF V IBRIO IN THE SHRIMP PONDS

There is close relationship between algae and microbes. The structure of bacterial community can be controlled by microalgae in the culture system of shrimp. The physiological capability capabilities of the microalgal cells are increased by the im -mobilization. After immobilized Oocystis borgei and Nannochloris oculata are artificially introduced into the culture systemof LitopPenaeus vannamei, the numbers of Vibrio are inspected in thewater, stomach and intestine posterior of shrimp to study the influence of immobilized microalgae over the quantity dynamics of Vibrio.The result shows that there is not detectable Vibrio in boththe culture systems with Oocystis borgei, Nannochloris oculata after 9 days, 15 days culture in this experiment respectively.Thereis not Vibrio in the culture system with microalga in the late period of culture. Introducing the algal alginate beads of Oocystisborgei and Nannochloris oculata into cultural environment of shrimp can inhibit growth of Vibrio. The numbers of Vibrio in thewater, stomach and intestine posterior of shrimp in the culture systemwith Oocystis borgei, Nannochloris oculata. Oocystis borgeimixing with Immobilized Nannochloris oculata are depressed 69192%, 63167%, 72107%; 71176%, 70179%, 79130% and80122%, 79112%, 81178% respectively in contrast to the control group. The inhibitory effect of immobilized Oocystis borgeimixing with immobilized Nannochloris oculata is brtter than immobilized Oocystis borgei and immobilized Oocystis borgei is betterthan immobilized Nannochloris oculata. The Vibrio numbers of the experiment group in the late period of the experiment are lessthan the early. The microalgas cell numbers in the algal beads begin to increase at second day of this experiment. The color ofthe algal alginate -beads is bottle green in the late period of the experiment.The cell numbers of immobilized Oocystis borgei andNannochloris oculata in the per bead increased from 0133@ 107to 3117@ 107cells and 1150@ 107to 25147 @ 107cells respec -tively and the biomass is increased about 10 and 17 times respectively in 21days of culture in this experiment. This proved thatthe physiological capabilities of the immobilized microalgal cells are not interrupted by the immobilization. Thus, the immobilizedmicroalgae can be used to micro -ecology control to prevent shrimp disease in the shrimp pond.