Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Environ Sci Technol. 2021 Apr 20;55(8):5559-5568. doi: 10.1021/acs.est.0c08355. Epub 2021 Mar 17.
The fate and transport of bacteria in porous media are essential for bioremediation and water quality control. However, the influence of biological activities like extracellular electron transfer (EET) and swimming motility toward granular media on cell transport remains unknown. Here, electroactive bacteria with higher Fe(III) reduction abilities were found to demonstrate greater retention in ferrihydrite-coated sand. Increasing the concentrations of the electron donor (1-10 mM lactate), shuttle (0-50 μM anthraquinone-2,6-disulfonate), and acceptor (ferrihydrite, MnO, or biochar) under flow conditions significantly reduced MR-1's mobility through redox-active porous media. The deficiency of EET ability or flagellar motion and inhibition of intracellular proton motive force, all of which are essential for energy taxis, enhanced MR-1's transport. It was proposed that EET could facilitate MR-1 to sense, tactically move toward, and attach on redox-active media surface, eventually improving its retention. Positive linear correlations were established among parameters describing MR-1's energy taxis ability (relative taxis index), cell transport behavior (dispersion coefficient and relative change of effluent percentage), and redox activity of media surface (reduction potential or electron-accepting rate), providing novel insights into the critical impacts of bacterial microscale motility on macroscale cell transport through porous media.
细菌在多孔介质中的运移和归宿对于生物修复和水质控制至关重要。然而，细胞输运过程中，生物活性如细胞外电子传递（EET）和游动能力对颗粒介质的影响仍不清楚。本研究发现，具有更高三价铁还原能力的电活性细菌在水铁矿涂层砂中表现出更高的滞留能力。在流动条件下，增加电子供体（1-10 mM 乳酸盐）、穿梭剂（0-50 μM 蒽醌-2,6-二磺酸钠）和受体（水铁矿、MnO 或生物炭）的浓度显著降低了 MR-1 通过氧化还原活性多孔介质的迁移能力。EET 能力或鞭毛运动的缺乏以及细胞内质子动力势的抑制，这些都是趋化性所必需的，从而增强了 MR-1 的迁移能力。提出 EET 可以促进 MR-1 感知、策略性地向氧化还原活性介质表面移动，并附着在表面上，最终提高其保留率。MR-1 的能量趋化能力（相对趋化指数）、细胞输运行为（弥散系数和流出百分比的相对变化）和介质表面氧化还原活性（还原电位或电子接受速率）等参数之间建立了正线性相关关系，为细菌微观运动对多孔介质中宏观细胞输运的关键影响提供了新的见解。
