| In recent years,entrophication and the algae blooms are widely acclaimed to occur and have caused serious ecological problems all over the world. So it's high time did research to resist alga, probing new economic, efficient and safe ways to fight with alga.This thesis puts much attention on the technological and large-scale fermentation of a kind of Algicidal Bacteria S4, which was collected form a piece of high-alga-risk area in this reservoir. First of all, the researcher ascertained the medium ratio for large-scale producing. Then did some relevant researches to analyze the influence this nutrient medium could give to the growth of alga. It is demonstrated by the experiment that this medium ratio supports no obvious promoting or restraining influence on the growth of Microcystic aeruginosa 905, Anabaena flos-aquae1092, Scenedesmus 45, Chlorella. This assures the authenticity of the following detection on the dissolving alga effect. The research also demonstrated that under the same outer condition, S4 bacterial strain grows better in this nutrient medium than in the traditional beef extract peptone medium. Through the research, we can also come to the conclusion that the original carbon source density also effects S4's growth. And the best kind and density is: soluble corn flour, 10g/l.The research made tertiary production of S4, respectively in 500ml conical flask, 5L and 500L fermentation tank. The researcher optimized the fermentation conditions in the conical flask by response surface methodology(RSM), and drawn the conclusion for the best choice on this occasion: temperature 31.8℃; PH 7.21,wave bed speed 180r/min, fluid volume 60%, inoculums'size 10%. After a close-up view of the whole gradually increasing fermentation process, the researcher found that there's a scale effect and the main reason is the blending degree of nutrient fluid and density of dissolved oxygen. Cycling culture used for the 5l fermentation tank can cultivate 3.4 times more Algicidal Bacteria than the traditional partial producing method. 500l tank takes 20% Cycling culture, it can also increase density of Algicidal Bacteria in the nutrient fluid.Fermentation liquor of Algicidal Bacteria can be used directly in the alga area, or it can be used by drying up after adding some supporter and being made into powder. This thesis also did relevant research on the powder bacteriolysant to test its effect. The best matching proportion between supporter and bacteria liquor is: saw dust: turf: bacteria liquor = 4:1:20. This medium ratio can get effect of 86.41 in 4 days if it is used under the dosing proportion of 1:1000. This medium ratio can keep 6 months and its effect is high on 80% even after 3 months. So it can satisfy the emergency needs to fight with alga. It is not instant so its treatment effect for Chlorophyll A in the test liquor is not that obvious. chitosan has the ability of flocculation, S4 alga-dissolving liquor will get this ability two when being packed by chitosan. This improved liquor obtains 91.25% treatment effect of Chlorophyll A. Even after 4 days, the effect is still high at 81.3%. It has high effects which is not that inclined to the periods. |
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