Kinetic affinity index informs the divisions of nitrate flux in aerobic denitrification

Yunjie Ruan; Bin Ma; Chen Cai; Lei Cai; Jun Gu; Hui-Feng Lu; Xiang-Yang Xu; Meng Zhang

doi:10.1016/j.biortech.2020.123345

Kinetic affinity index informs the divisions of nitrate flux in aerobic denitrification

Bioresour Technol. 2020 Aug:309:123345. doi: 10.1016/j.biortech.2020.123345. Epub 2020 Apr 8.

Authors

Yunjie Ruan¹, Bin Ma², Chen Cai³, Lei Cai⁴, Jun Gu⁵, Hui-Feng Lu⁶, Xiang-Yang Xu⁶, Meng Zhang⁷

Affiliations

¹ Institute of Agricultural Bio-Environmental Engineering, College of Bio-Systems Engineering and Food Science, Zhejiang University, Hangzhou 310058, PR China; The Rural Development Academy, Zhejiang University, Hangzhou 310058, PR China.
² Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
³ Advanced Water Management Centre, Faculty of Engineering, Architecture and Information Technology, The University of Queensland, Brisbane, QLD 4072, Australia.
⁴ Laboratory of Microbial Resources, College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310035, China.
⁵ Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, Singapore, Singapore.
⁶ Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
⁷ Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China; Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, Singapore, Singapore. Electronic address: zhang.meng@ntu.edu.sg.

PMID: 32305844
DOI: 10.1016/j.biortech.2020.123345

Abstract

Aerobic denitrification is attracting increasing attention since its advantage of complete nitrogen removal in a single aerobic reactor with simplified configurations. This study investigated the nitrate kinetic affinity (half-saturation index, K_m) by an isolated aerobic denitrifier named P. balearica strain RAD-17. It turned out that strain RAD-17 had a high K_m of 162.5 mg-N/L and maximum nitrate reduction rate of 21.7 mg-N/(L•h), enabling it to treat high-strength nitrogen wastewater with high efficiency. Further analysis illustrated that K_m was the critical value for the change of growth yield rate along initial nitrate concentrations. Nitrogen balance results elucidated an opposite nitrogen flux to cell synthesis and nitrogen loss during aerobic denitrification. Moreover, the expression of functional genes provided proofs for these phenotypic results at transcriptional level. Consequently, K_m could be an indicator for nitrate flux division directing to respiration and assimilation in aerobic denitrifiers, shedding light on its regulation for wastewater treatment.

Keywords: Aerobic denitrification; Gene transcriptional expression; Growth characteristics; Kinetic affinity; Nitrogen balance.

MeSH terms

Aerobiosis
Denitrification*
Nitrates*
Nitrification
Nitrogen
Wastewater

Substances

Nitrates
Waste Water
Nitrogen