The present study investigates the changes in the microbial community and the degradation of organic compounds in microbial fuel cells (MFCs) operated on human urine. An anaerobic community was enriched in “urine-degrading” electroactive microorganisms by stepwise lowering the dilution factor of the anode media from 50 times diluted to undiluted urine. In a duplicated assay a current density of 495 ± 16 mA m⁻², a chemical oxygen demand (COD) removal of 75.5 ± 0.7% and a coulombic efficiency (CE) of 26.5 ± 0.7% were obtained during operation on undiluted urine. In a control assay, operated on undiluted urine without the microbial enrichment procedure, a current density of only 81 ± 9 mA m⁻² was obtained. The organic compounds commonly found in urine as well as the metabolic products associated with their degradation were analyzed by proton nuclear magnetic resonance (¹H-NMR). The main compounds initially identified in the urine were urea, creatinine, glycine, trimethylamine N-oxide and acetate. Most of the organic compounds, except acetate, were depleted within 10 days of operation. The microbial community responsible for urine degradation in the anode of both MFCs was investigated using the Illumina MiSeq platform. Bacteria related with the Firmicutes phyla were enriched in the anodic biofilms compared to the initial anaerobic inoculum, within which Tissierella and Paenibacillus were the dominant genera. Tissierella can metabolize creatinine producing acetate whereas several bacterial species belonging to the Paenibacillus genus demonstrated the ability to function as exoelectrogens. Corynebacterium that comprise urea-hydrolysing bacteria was also amongst the main genera detected in the developed biofilms.

中文翻译：

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研究在真实人类尿液上运行的微生物燃料电池中细菌群落的变化和有机底物的降解

本研究调查了在人类尿液上操作的微生物燃料电池（MFCs）中微生物群落的变化和有机化合物的降解。通过逐步将阳极介质的稀释因子从50倍稀释为未稀释尿液，可以使厌氧菌富集“降解尿液”的电活性微生物。在重复测定中，在未稀释尿液的操作过程中，获得了495±16 mA m ^-2的电流密度，75.5±0.7％的化学需氧量（COD）去除和26.5±0.7％的库仑效率（CE）。在未经微生物富集程序的情况下对未稀释尿液进行操作的对照测定中，电流密度仅为81±9 mA m ^-2获得了。通过质子核磁共振（¹ H-NMR）分析了尿液中常见的有机化合物及其降解相关的代谢产物。最初在尿液中鉴定出的主要化合物是尿素，肌酐，甘氨酸，三甲胺N-氧化物和乙酸盐。除乙酸盐外，大多数有机化合物在运行10天之内就被消耗掉了。使用Illumina MiSeq平台研究了导致两个MFC阳极尿液降解的微生物群落。与最初的厌氧接种菌相比，与菌门相关的细菌在阳极生物膜中富集，其中以Tissierella和Paenibacillus为主要属。Tissierella可以代谢产生肌酸酐的乙酸盐，而属于Paenibacillus属的几种细菌则证明具有作为外生电子的功能。包括尿素水解细菌的棒杆菌也是在已开发的生物膜中检测到的主要属之一。