Analysis Of Bacteria Structure And Diversity In Megalobrama Amblycephala Breeding System

In recent years, an increasing correlation has been observed between microorganism and local environmental conditions. Therefore, the present study seeks to determine the effects of different months on diversity analysis of community structure characteristics and composition in microorganism of water environment and bottom mud for aquaculture.In terms of the structure characteristics in bacteria communities:In present study, the test samples were obtained form the Yixing fish farm of the Fresh-water Fisheries Research Center, Chinese Academy of Fishery Sciences for 12 months. The biological diversity of community structure characteristics and composition in microorganism of different breeding sites of water (the culture system of the inlet? impounding reservoir?breeding pond) and bottom mud for aquaculture were analyzed by PCR-DGGE. The results as follows:(1) The most obvious diversity of bacteria community in water environment for aquaculture was observed in summer (P<0.05), the next is spring, and autumn and winter are finally. During the spring and summer breeding period, there is a trend that the diversity of bacteria communities increases gradually, from the water inlets to the reservoir, and finanlly to the aquiculture pond. However, we have the contrary trend during autum and winter. In addition, the similarity (>57%) of bacteria species of water environment for aquaculture in spring, autum and winter were significantly highest than that (>47%) bacteria species in summer. Our results indicated that the temperature and site are the factors that result in the change of diversity of bacteria community. (2) During the whole breeding period, the highest diversity of bacteria community of different sediment levels in aquaculture pond was observed in autum, the next is winter, and the finally are spring and summer. Sediment microbes mainly live in the upper-middle level of the sediment. The bottom sediment samples have the lowest bacteria diversity, and the community structure tends to be stable. The microbe quantity donesn't change significantly in the sediment samples of adjacent layers, and the community structure also tends to be stable and little difference. In addition, the similarity(>63%) of bacteria structure of sediment in winter, autumn and spring were significantly higher than that of structure in summer. The results indicated that different season and distribution could obvious affect the diversity of sediments bacteria.In terms of the compose diversity in bacteria communities:(1)In Megalobrama amblycephala culture cycles, the different sites (the culture system of the inlet? impounding reservoir?breeding pond) of water had different characteristic bands. The cloning sequence in spring and winter belonged to four bacterial phylums: Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria; In addition belonged to the common four bacterial phylums, the cloning sequence in autumn started to appear Firmicutes bacterial phylums; while the cloning sequence in summmer except belonged to the common five bacterial phylums in above three culture cycles,it started to appear Chloroflexi bacterial phylums.The Proteobacteria and Actinobacteria which consisted mainly of ?-Proteobacteria was the dominant group in Megalobrama amblycephala in autume and winter culture cycles, while a-Proteobacteria was the dominant group in spring, ?-Proteobacteria and ?-Proteobacteria in summer. (2)In rearing pond sediments, the bacteria species in the whole culture cycles existed certain differences. The Proteobacteria and Chloroflexi were the dominant group in Megalobrama amblycephala culture cycles, which consisted mainly of ?-Proteobacteria in spring and summer culture cycles, a-Proteobacteria and ?-Proteobacteria in summer,?-Proteobacteria in autume,?-Proteobacteria in winter. Some bacteria with different depths, sites and culture period presented certain distribution characteristics.some bacteria changed alter or replace, which can be thought of the performance of the bacteria adapt to the environment. This research found that the water and sediment of the hybrid culture pond which predominantly cultured Megalobrama amblycephala, excised a variety of aerobic bacteria and anaerobic bacteria. The interaction of the bacteria which ensured the normal conduct of cultivation.Therefore, the mode which predominantly cultured Megalobrama amblycephala and keep the other species was beneficial to the culture environment.