| As sea cage culture is a high-density and high feeding artificial breeding method,its output (including bait and waste of metabolism and excretion)leading to high nutrient loads in sea water caused eutrophication in sea water aquaculture,which provided material foundation to occurrence of red tide and become incentives of occurrence of red tide. It is founded by survey that content of nitrogen and phosphorus is very rich in most eutrophication water, especilly inorganic nitrogen pollution most serious. Inorganic nitrogen pollution in Marine cage culture environment restricts the economic benefits and development of aquaculture seriously. Aerobic denitrifying bacteria with unique advantages compared with traditional anaerobic denitrifying bacteria as a new technology for biological nitrogen removal has been suitable for nitrogen pollution control in large-scale water. In this study, Aerobic denitrifying bacteria for removal of inorganic nitrogen were screened from the sediment in the marine cage fish farm in Dapeng Ao Cove in the east coast of Shenzhen City, it have some scientific significance to further explore bio-situ remediation of inorganic nitrogen for polluted sediment environment in marine cage farm, solve the environmental constraints for marine cage fish farming industry. The results are as followings.1.In this study, aerobic denitrifying bacterias were enriched by adding nitrate quantitatively and control of aeration to improve nitrate removal rate of bacterias under aerobic conditions, there are 10 aerobic denitrifying bacterias were isolated, they are strain N41-1,N41-2,N42-1,N42-2,N42-3,N51-1,N51-2,N51-5 and N52-1. Two aerobic denitrifying bacterias N42-2 and N52-1, which effectively decreased nitrite and nitrate concentrations during 3-10days, in which N42-2 has a NO2--N removal rate of 99.5% and a NO3--N removal rate of 98.1%, N52-1 has a NO2--N removal rate of 95.8% and a NO3--N removal rate of 100%, were screened from enriched aerobic denitrifying bacterias by denitrification performance tests.2.Sequence analysis based on partial 16SrDNA and performed by BioEdit and MEGA3.0 showed that the strains N42-2 and N52-1 were the closet relative of Halomonas sp. with 99% sequence similarity and high homology, combined with morphological and physiological biochemical characteristics of bacteria showed that strains N42-2 and N52-1 all belonged to genus of Halomonas sp.3.It is showed by experimental restoration of inorganic nitrogen in simulated marine cage culture environment that, strain N42-2 with higher effectively denitrification capacity compared with N52-1.The denitrifation Comparison of restoration of inorganic nitrogen of two strains in simulated marine cage farms environment, although the 2 strains all have a denitrification capacity of NO3--N are capacity, bacteria of N42-2 has a better biological restoration ability than N52-1. Bacteria of N42-2 has denitrification capacity of NO3--N to a certain extent under different test conditions, with a removal rate of NO3--N up to 94.6%, while bacteria of N52-1 has a denitrification capacity of NO3--N only at 20℃.4.1t is obtained by a comprehensive comparison of denitrification results of aerobic denitrifying bacterias at 20℃and 28℃that,20℃is the better temperature to simulate inorganic nitrogen bioremediation experiment in marine cage farms environment.
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