Isolation and Denitrification Characteristics of Salt-tolerant Aerobic Denitrifier Marinobacter sp.Strain B108

WANG Jiao; LIN Jiushu; WANG Wenxin; WANG Fuhai; MU Minghao; HONG Bo; JI Junyuan

doi:10.19672/j.cnki.1003-6504.0542.23.338

Abstract：A high-efficient aerobic denitrifier was successfully isolated from the biological aerated filter of the marine recir-culating aquaculture system(MRAS)belonging to an aquaculture company in Yantai.The isolated strain was identified as Marinobacter and termed Marinobacter sp.strain B108 based on its morphological characteristics and 16S rRNA analysis.The optimal factors affecting the nitrogen removal performances of Marinobacter sp.strain B108 were determined through single-factor experimental analysis.The growth characteristics,aerobic denitrification performance and nitrogen balance were also clarified under the optimal conditions.Marinobacter sp.strain B108 has high-efficient aerobic denitrification performance,and no heterotrophic nitrification capability.The optimal factors were CH3COONa as carbon source,C/N ratio 16,salinity 30‰.The NO3--N and TN removal efficiencies of Marinobacter sp.strain B108 under the optimum conditions in 24 hours were 100％and 98.89％with nitrate(102.86 mg/L)as the substrate,respectively.The NH4+-N removal efficiency under the optimum conditions in 24 hours was 55.85％.The NH4+-N removed was completely converted into intracellular nitrogen,and NO3--N and NO2--N were not detected during the degradation process.Nitrogen balance analysis showed that the assimilation rates of NO3--N,NO2--N and NH4+-N by Marinobacter sp.strain B108 were 36.53％,38.80％and 50.47％,respectively.At the same time,the rates of nitrogen loss in the form of gases were 62.48％,47.55％and 1.12％,respectively.The nitrate reduction metabolic pathway of Marinobacter sp.strain B108 comprise the assimilatory nitrate reduction to ammonium and dissimilato-ry nitrate reduction based on aerobic denitrification,not include the dissimilatory nitrate reduction to ammonium.The nitrogen removal is mainly performed through aerobic denitrification.Marinobacter sp.strain B108 shows a broad application prospect in nitrate treatment of marine recirculating aquaculture.