Abstract. Microbial fuel cell (MFC) is an efficient in-situ approach to combat pollutants and generate electricity. This study constructed a soil MFC (SMFC) to reduce Cr(VI) in paddy soil and investigate its influence on microbial community and microbial resistance characteristics. Fe₃O₄ nanoparticle as the cathodic catalyst effectively boosted power generation (0.97 V, 102.0 mW/m²), whose porous structure and reducibility also contributed to Cr reduction and immobilization. After 30 days, 93.67 % of Cr(VI) was eliminated. The bioavailable Cr decreased by 97.44 % while the residual form increased by 88.89 %. SMFC operation greatly changed soil enzymatic activity and microbial structure, with exoelectrogens like Desulfotomaculum (3.32 % in anode) and Cr(VI)-reducing bacteria like Hydrogenophaga (2.07 % in cathode) more than 1000 folds of soil. In particular, SMFC operation significantly enhanced the abundance of heavy metal resistance genes (HRGs). Among them, chrA, chrB, and chrR increased by 99.54~3314.34 % in SMFC anode than control, probably attributed to the enrichment of potential tolerators like Acinetobacter, Limnohabitans, and Desulfotomaculum. These key taxa were positively correlated with HRGs but negatively correlated with pH, EC, and Cr(VI), which could have driven Cr(VI) reduction. This study provided novel evidence for bioelectrochemical system application in contaminated paddy soil, which could be a potential approach for environmental remediation and detoxification.

中文翻译：

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微生物燃料电池运行下稻田土壤中 Cr(VI) 的还原、发电和微生物抗性变化


摘要。微生物燃料电池（MFC）是一种有效的原位消除污染物和发电的方法。本研究构建了土壤MFC（SMFC）来还原水稻土中的Cr（VI），并研究其对微生物群落和微生物抗性特征的影响。 Fe ₃ O ₄纳米粒子作为阴极催化剂有效地提高了发电量（0.97 V，102.0 mW/m ² ），其多孔结构和还原性也有助于Cr的还原和固定。 30 天后，93.67% 的 Cr(VI) 被消除。生物利用度Cr下降了97.44%，而残留形式增加了88.89%。 SMFC 的运行极大地改变了土壤酶活性和微生物结构， Desulfotomaculum （阳极中的 3.32%）等产电体和Hydrogenophaga （阴极中的 2.07%）等 Cr(VI) 还原细菌超过土壤的 1000 倍。特别是，SMFC 的运行显着提高了重金属抗性基因（HRG）的丰度。其中，SMFC阳极中的chrA、chrB和chrR比对照增加了99.54~3314.34%，这可能归因于不动杆菌、Limnohabitans和Desulfotomaculum等潜在耐受菌的富集。这些关键类群与 HRG 呈正相关，但与 pH、EC 和 Cr(VI) 呈负相关，这可能导致 Cr(VI) 减少。该研究为生物电化学系统在污染稻田土壤中的应用提供了新的证据，这可能成为环境修复和解毒的潜在方法。