title: Characteristics of a Novel Aerobic Denitrifying Bacterium, Enterobacter cloacae Strain HNR.
abstract: A novel aerobic denitrifier strain HNR, isolated from activated sludge, was identified as Enterobacter cloacae by16S rRNA sequencing analysis. Glucose was considered as the most favorable C-source for strain HNR. The logistic equation well described the bacterial growth, yielding a maximum growth rate (μmax) of 0.283 h(-1) with an initial NO3 (-)-N concentration of 110 mg/L. Almost all NO3 (-)-N was removed aerobically within 30 h with an average removal rate of 4.58 mg N L(-1) h(-1). Nitrogen balance analysis revealed that proximately 70.8 % of NO3 (-)-N was removed as gas products and only 20.7 % was transformed into biomass. GC-MS result indicates that N2 was the end product of aerobic denitrification. The enzyme activities of nitrate reductase and nitrite reductase, which are related to the process of aerobic denitrification, were 0.0688 and 0.0054 U/mg protein, respectively. Thus, the aerobic denitrification of reducing NO3 (-) to N2 by strain HNR was demonstrated. The optimal conditions for nitrate removal were C/N ratio 13, pH value 8, shaking speed 127 rpm and temperature 30 °C. These findings show that E. cloacae strain HNR has a potential application on wastewater treatment to achieve nitrate removal under aerobic conditions.
authors.affiliation: The Key Laboratory of Eco-environments in Three Gorges Reservoir Region, College of Urban Construction & Environmental Engineering, Chongqing University, Chongqing, 400045, People's Republic of China.
authors.forename: Long-Jie
authors.initials: LJ
authors.lastname: Guo
authors.affiliation: The Key Laboratory of Eco-environments in Three Gorges Reservoir Region, College of Urban Construction & Environmental Engineering, Chongqing University, Chongqing, 400045, People's Republic of China. binzhao11@cqu.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.affiliation: The Key Laboratory of Eco-environments in Three Gorges Reservoir Region, College of Urban Construction & Environmental Engineering, Chongqing University, Chongqing, 400045, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: An
authors.affiliation: National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing, 400045, People's Republic of China.
authors.forename: Meng
authors.initials: M
authors.lastname: Tian
mesh_terms: D000332:Aerobiosis; D058440:Denitrification; D016972:Enterobacter cloacae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012722:Sewage
keywords: Aerobic denitrification; Nitrate reductase; Nitrate removal; Nitrite reductase; Nitrogen balance