title: Enhanced denitrification of Pseudomonas stutzeri by a bioelectrochemical system assisted with solid-phase humin.
abstract: The denitrification reactions performed by Pseudomonas stutzeri JCM20778 were enhanced electrochemically with the use of solid-phase humin, although P. stutzeri itself was incapable of receiving electrons directly from the graphite electrode. Electrochemically reduced humin enhanced the microbial, but not abiotic, denitrification reactions. Electric current and cyclic voltammetry analyses suggested that the solid-phase humin functioned as an electron donor for the denitrification reactions of P. stutzeri. Nitrogen balance study and the estimation of the first-order rate constants of the consecutive denitrification reactions suggested that the solid-phase humin enhanced all reducing reactions from nitrate to nitrogen gas. Considering the wide distribution of humin in the environment, the findings that solid-phase humin can assist in electron transfer, from the electrode to a denitrifying bacterium that has little ability to directly utilize external electrons, has important implications for the widespread application of bioelectrochemical systems assisted by solid-phase humin for enhancing microbial denitrification.
authors.affiliation: Department of Civil Engineering, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Zhixing
authors.initials: Z
authors.lastname: Xiao
authors.affiliation: Department of Civil Engineering, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan; EcoTopia Science Institute, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Takanori
authors.initials: T
authors.lastname: Awata
authors.affiliation: Department of Civil Engineering, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Zhang
authors.affiliation: EcoTopia Science Institute, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Chunfang
authors.initials: C
authors.lastname: Zhang
authors.affiliation: EcoTopia Science Institute, Nagoya University, Chikusa, Nagoya 464-8603, Japan.
authors.forename: Zhiling
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Civil Engineering, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan; EcoTopia Science Institute, Nagoya University, Chikusa, Nagoya 464-8603, Japan. Electronic address: a-katayama@esi.nagoya-u.ac.jp.
authors.forename: Arata
authors.initials: A
authors.lastname: Katayama
mesh_terms: D058440:Denitrification; D004560:Electricity; D055664:Electrochemical Techniques; D004566:Electrodes; D004579:Electron Transport; D004583:Electrons; D006812:Humic Substances; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D044223:Pseudomonas stutzeri / Q000378:metabolism*
chemical_list: D006812:Humic Substances; D009566:Nitrates; C001861:humin; D009584:Nitrogen
keywords: Bioelectrochemical system; Denitrification; Pseudomonas stutzeri; Redox mediator; Solid-phase humin