Mechanisms of synthesis and maintenance of reduced solid humic substances functioning as energy source for anaerobic microorganisms remediating the environment

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H01899
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Modeling and technologies for environmental conservation and remediation
• Research Institution: Nagoya University
• Principal Investigator: Katayama Arata 名古屋大学, 未来材料・システム研究所, 教授 (60185808)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 固体腐植ヒューミン / 細胞外電子伝達 / 化学構造解析 / 嫌気性微生物 / 最終電子受容体

Outline of Final Research Achievements

This study aimed to elucidate the formation and maintenance mechanism of solid-phase　humic substance (humin, humic substances insoluble in any pH), functioning as energy source for the reducing reactions of anaerobic microorganisms, important reactions for environmental remediation. Carried out were the chemical structural analysis of redox center in humin, its electrochemical characterization, and the analysis of community structure of anaerobic microbial consortium reducing humin. The comparative study of the various spectra for humins with different extracellular electron mediating efficiencies suggested the association of peptide glycan structure in the extracellular electron mediating function. Electrochemical analysis using electrochemical impedance spectra showed the trend agreeing with the microbial metabolism but not with the values. Microbial consortium containing the reaction of humin reduction was composed of mostly Clostridiales (>90%).

Free Research Field

環境生物工学

Academic Significance and Societal Importance of the Research Achievements

土壌や底質に広く存在する腐植物質、特にその中でもかなりの割合を占める有機無機複合体である固体腐植ヒューミンが、嫌気性微生物に対して電気的エネルギー源として機能する機構の解析は、これまで不明であったエネルギー欠乏条件の自然環境の中で生残する微生物戦略の解明につながると同時に、それを利用して環境中で得られる小電力を利用した自立分散型の環境浄化システムの構築の端緒にもつながるものとして期待される。