Effects and mechanisms of modified biochars on microbial iron reduction of Geobacter sulfurreducens. (November 2021)

• Record Type: Journal Article
• Authors: Lu, Yue; Hu, Yingju; Tang, Lin; Xie, Qingqing; Liu, Qian; Zhong, Linrui; Fu, Leiling; Fan, Changzheng
• Is Part Of: Chemosphere. Volume 283(2021)
• Publication Date: 2021-11
• Subjects: Modified biochars -- Microbial iron reduction -- Extracellular electron transfer -- Electron shuttle -- Surface functional groups; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.130983
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Biochar was proved as an electron shuttle to facilitate extracellular electron transfer (EET) of electrochemically active bacteria (EAB); however, its underlying mechanism was not fully understood. In this study, we aimed to further explore how the regulation of surface functional groups of biochar would affect the microbial iron reduction process of Geobacter sulfurreducens as a typical EAB. Two modified biochars were achieved after HNO3 (NBC) and NaBH4 (RBC) pretreatments, and a control biochar was produced after deionized water (WBC) washing. Results showed that WBC and RBC significantly accelerated microbial iron reduction of G. sulfurreducens PCA, while had no effect in the final Fe (II) minerals (e.g., vivianite and green rust (CO3 2− )). Besides, Brunauer-Emmett-Teller (BET) surface area, electron spin resonance (ESR) and electrochemical measurements showed that larger surface area, lower redox potential, and more redox-active groups (e.g., aromatic structures and quinone/hydroquinone moieties) in RBC explained its better electron transfer performance comparing to WBC. Interestingly, NBC completely suppressed the Fe (III) reduction process, mainly due to the production of reactive oxygen species which inhibited the growth of G . sulfurreducens PCA. Overall, this work paves a feasible way to regulate the surface functional groups for biochar, and comprehensively revealed its effect on EET process of microorganisms. Graphical abstract: Image 1 Highlights: Three biochars (RBC/NBC/WBC) were gained by reduced/oxidized/neutral pretreatment. RBC was optimal electron shuttle for Geobacter sulfurreducens PCA. WBC and RBC significantly accelerated the microbial iron reduction of strain PCA. Abundant redox-active groups endowed better electron transfer performance of RBC. NBC inhibited the Fe (III) reduction of strain PCA due to its biotoxicity.