Isolation of a Strain of Denitrifying Bacterium and its Denitrification Characteristics
ZHANG Chun-yang et al(School of Life Science,Shandong University of Technology,Zibo,Shandong 255091)
[Objective] The purpose was to study the elimination on nitrogen pollution by microorganisms and provide base for better development and utilization of denitrifying bacterium in production practice.[Method] By directional enrichment method,a denitrifying bacterium D3 was isolated from the active sludge collected in the wastewater treatment system of a printing and dyeing plant in Zibo city and its denitrifying characteristic was researched systemically.[Result] The denitrifying bacterium D3 was Gram negative short rod bacterium.It could eliminate 10.43%～13.13% nitrate in the defined denitrifying medium in 60 h.It could make use of sucrose,glucose,acetate,citrate sodium and sodium bicarbonate as single carbon source for denitrification,in which citrate sodium was the optimum one.The suitable molar ratio of carbon/nitrogen for denitrification of the bacterium was 12.0∶1.0.The optimum inoculation concentration was 9.6×108 CFU/L.[Conclusion] Additions containing organic nitrogen such as beef extract,yeast extract,peptone and acetamide could not promote the elimination of nitrate effectively,while the denitrifying bacterium D3 was more suitable for the nitrate elimination in some industrial wastewater containing less organic nitrogen.