title: Microbial community structure and function of nitrobenzene reduction biocathode in response to carbon source switchover.
abstract: The stress of poised cathode potential condition and carbon source switchover for functional biocathode microbial community influences is poorly understood. Using high-throughput functional gene array (GeoChip v4.2) and Illumina 16S rRNA gene MiSeq sequencing, we investigated the phylogenetic and functional microbial community of the initial inoculum and biocathode for bioelectrochemical reduction of nitrobenzene to less toxic aniline in response to carbon source switchover (from organic glucose to inorganic bicarbonate). Selective transformation of nitrobenzene to aniline maintained in the bicarbonate fed biocathode although nitrobenzene reduction rate and aniline formation rate were significantly decreased compared to those of the glucose-fed biocathode. When the electrical circuit of the glucose-fed biocathode was disconnected, both rates of nitrobenzene reduction and of aniline formation were markedly decreased, confirming the essential role of an applied electric field for the enhancement of nitrobenzene reduction. The stress of poised cathode potential condition led to clear succession of microbial communities from the initial inoculum to biocathode and the carbon source switchover obviously changed the microbial community structure of biocathode. Most of the dominant genera were capable of reducing nitroaromatics to the corresponding aromatic amines regardless of the performance mode. Heterotrophic Enterococcus was dominant in the glucose-fed biocathode while autotrophic Paracoccus and Variovorax were dominant in the bicarbonate-fed biocathode. Relatively higher intensity of diverse multi-heme cytochrome c (putatively involved in electrons transfer) and carbon fixation genes was observed in the biocarbonate-fed biocathode, likely met the requirement of the energy conservation and maintained the nitrobenzene selective reduction capability after carbon source switchover. Extracellular pilin, which are important for biofilm formation and potential conductivity, had a higher gene abundance in the glucose-fed biocathode might explain the enhancement of electro-catalysis activity for nitrobenzene reduction with glucose supply. Dominant nitroaromatics-reducing or electrochemically active bacteria and diverse functional genes related to electrons transfer and nitroaromatics reduction were associated with nitrobenzene reduction efficiency of biocathode communities in response to carbon source switchover.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
authors.forename: Haoyi
authors.initials: H
authors.lastname: Cheng
authors.affiliation: Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.affiliation: Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Jincai
authors.initials: J
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Deyong
authors.initials: D
authors.lastname: Kong
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China.
authors.forename: Wenzong
authors.initials: W
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China.
authors.forename: Nanqi
authors.initials: N
authors.lastname: Ren
authors.affiliation: Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Liyou
authors.initials: L
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, PR China. Electronic address: waj0578@hit.edu.cn.
authors.forename: Aijie
authors.initials: A
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, PR China; Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan. Electronic address: djlee@ntu.edu.tw.
authors.forename: Duu-Jong
authors.initials: DJ
authors.lastname: Lee
authors.affiliation: Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA; State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China; Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry / Q000378:metabolism; D052818:Autotrophic Processes / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D001483:Base Sequence; D001674:Bioelectric Energy Sources; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D002244:Carbon / Q000494:pharmacology*; D057486:Carbon Cycle / Q000187:drug effects; D016000:Cluster Analysis; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004553:Electric Conductivity; D004566:Electrodes; D004583:Electrons; D036781:Fimbriae Proteins / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D016014:Linear Models; D009578:Nitrobenzenes / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010802:Phylogeny; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000814:Aniline Compounds; D009578:Nitrobenzenes; D012336:RNA, Ribosomal, 16S; D036781:Fimbriae Proteins; D002244:Carbon; D003577:Cytochrome P-450 Enzyme System; C036077:nitrobenzene; C023650:aniline
keywords: Biocathode; Carbon source switchover; Function; Microbial community structure; Nitrobenzene reduction