In natural or engineered anaerobic environments, iron oxidation-driven microbial denitrification plays a critical role in the water or wastewater treatment. Herein, we report a previously unidentified metallic iron (Fe⁰)-dependent denitrification mode driven by the electro-syntrophic interaction between electroactive microorganism and denitrifier. In a model denitrifying consortium of Shewanella oneidensis and Pseudomonas aeruginosa, we find that P. aeruginosa can accept electrons for nitrate reduction via the constructed electron transfer system of Fe⁰–S. oneidensis–P. aeruginosa. In the electro-syntrophic consortium, the membrane-bound CymA–OmcA–MtrC protein complexes of S. oneidensis drive the generation, transfer and consumption of electrons, thus enabling modulation of microbial metabolic activity. Specially, using Fe⁰ as the sole electron donor, S. oneidensis can act as a bio-engine to harvest electrons and conserve energy from Fe⁰ biocorrosion. Electrons released by S. oneidensis are utilized by P. aeruginosa for accomplishing microbial denitrification. Metatranscriptomics analysis demonstrated that the direct electron cross-feeding process facilitates the expression of genes encoding for denitrification enzymes, intracellular electron transfer proteins, and quorum sensing of P. aeruginosa. The Fe⁰-dependent electronic syntrophy in this work could provide a metabolic window for the growth of denitrifiers that is a new insight into nitrate removal or global nitrogen cycle.

中文翻译：

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电syntrophy驱动调节Fe0依赖性微生物反硝化作用


在自然或工程厌氧环境中，铁氧化驱动的微生物反硝化在水或废水处理中起着关键作用。在此，我们报道了一种以前未鉴定的金属铁 （Fe⁰） 依赖性反硝化模式，该模式由电活性微生物和反硝化剂之间的电共养相互作用驱动。在 Shewanella oneidensis 和 Pseudomonas aeruginosa 的模型反化联盟中，我们发现铜绿假单胞菌可以通过构建的 Fe^0-S. oneidensis-P. aeruginosa 的电子转移系统接受电子进行硝酸盐还原。在电共养联盟中，S. oneidensis 的膜结合 CymA-OmcA-MtrC 蛋白复合物驱动电子的产生、转移和消耗，从而能够调节微生物代谢活性。特别是，使用 Fe⁰ 作为唯一的电子供体，S. oneidensis 可以充当生物引擎来收集电子并保存 Fe⁰ 生物腐蚀的能量。铜绿假单胞菌利用 S. oneidensis 释放的电子来完成微生物反硝化。元转录组学分析表明，直接电子交叉喂养过程促进了编码反硝化酶、细胞内电子转移蛋白和铜绿假单胞菌群体感应的基因的表达。这项工作中的 Fe⁰ 依赖性电子共养可能为反式剂的生长提供一个代谢窗口，这是对硝酸盐去除或整体氮循环的新见解。