title: Dissimilatory nitrate reduction by Pseudomonas alcaliphila with an electrode as the sole electron donor.
abstract: Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were considered two alternative pathways of dissimilatory nitrate reduction. In this study, we firstly reported that both denitrification and DNRA occurred in Pseudomonas alcaliphila strain MBR with an electrode as the sole electron donor in a double chamber bio-electrochemical system (BES). The initial concentration of nitrate appeared as a factor determining the type of nitrate reduction with electrode as the sole electron donor at the same potential (-500 mV). As the initial concentration of nitrate increased, the fraction of nitrate reduced through denitrification also increased. While nitrite (1.38 ± 0.04 mM) was used as electron acceptor instead of nitrate, the electrons recovery via DNRA and denitrification were 43.06 ± 1.02% and 50.51 ± 1.37%, respectively. The electrochemical activities and surface topography of the working electrode catalyzed by strain MBR were evaluated by cyclic voltammetry and scanning electron microscopy. The results suggested that cells of strain MBR were adhered to the electrode, playing the role of electron transfer media for nitrate and nitrite reduction. Thus, for the first time, the results that DNRA and denitrification occurred simultaneously were confirmed by powering the strain with electricity. The study further expanded the range of metabolic reactions and had potential value for the recognization of dissimilatory nitrate reduction in various ecosystems.
authors.affiliation: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China.
authors.forename: Wentao
authors.initials: W
authors.lastname: Su
authors.forename: Lixia
authors.initials: L
authors.lastname: Zhang
authors.forename: Daping
authors.initials: D
authors.lastname: Li
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Zhan
authors.forename: Junwei
authors.initials: J
authors.lastname: Qian
authors.forename: Yong
authors.initials: Y
authors.lastname: Tao
mesh_terms: D001422:Bacterial Adhesion; D004566:Electrodes / Q000382:microbiology*; D004583:Electrons; D008855:Microscopy, Electron, Scanning; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010084:Oxidation-Reduction; D011549:Pseudomonas / Q000378:metabolism*; D000644:Quaternary Ammonium Compounds / Q000378:metabolism
chemical_list: D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds