极性反转MFC中电化学活性菌及其电子传递机制研究

In bioelectrochemical system (BES), the acceleration of recalcitrant compound degradation, self-buffering of electrolyte and quick establishment of biocathode can be achieved using polarity-inverting mode. However, there is little knowledge about polarity-inverting microbiology and the associated electron transfer mechanism. This study focuses on as follows:(1) Different inocula are inoculated into the polarity-inverting microbial fuel cells (PIMFCs), bio-samples are regularly collected and sequenced to obtain the evolution and structure information of the polarity-inverting microbial consortia, which are used to infer the metabolic ways of each constituted genus and their interaction for substrate degradation and electricity generation; (2) The pure strains are isolated from the mixed polarity-inverting consortia and inoculated into PIMFCs for polarity-inverting tests, the pure strains are sequenced to ascertain the mumber correspondences between the mixed consortia and pure stains; (3) Standard voltammograms of electrochemically active components are built by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), the electron transfer pathways and the involved active components are identified by comparing CVs and DPVs of the original mixed/pure biofilms with those of standard active components, the apparent endogenous energy comsuption for metabolism and voltage output are caculated based on the thermodynamic and electrochemical theories, finally, the regulating ways of energy metabolism in polarity-inverting bacteria are concluded. This study will provide insight to polarity-inverting processes and theoretical basis for their potential applications.

极性反转在生物电化学系统(Bioelectrochemical system, BES)中能够促进难降解物分解，实现pH自缓冲，快速获取生物阴极功能菌。然而，极性反转电化学活性菌的微生物学及产电机制信息相对较少。本研究拟：（1）接种不同微生物于极性反转MFCs中，定期取测生物样品，揭示极性反转混菌落结构及其演替规律，解析其中各菌属代谢功能及相互作用关系；（2）分离极性反转混菌落中各组成纯菌，并接种于极性反转MFCs中检验各菌株功能性，依据高通量测序，解析混菌/纯菌对应关系；（3）通过循环伏安及差分脉冲伏安法构建标准活性组分谱图，并以此鉴定极性反转混菌/纯菌电子传递途径及所涉及活性组分，进而结合热力学和电化学理论计算表观内源代谢耗能和电池能量输出，总结功能菌极性反转时的能量代谢调节规律。本项目的成功实施，将深化对极性反转过程的认识，为极性反转菌的潜在应用提供理论基础。

极性反转电极在生物电化学系统(Bioelectrochemical system, BES)中能够实现pH自缓冲，抑制产甲烷，改善电极反应动力学，促进难降解物分解。本项目研究了：（1）极性反转微生物燃料电池（microbial fuel cell, MFC）可长期稳定输出0.25-0.30 V电压，极性反转功率密度比非极性反转提高48.38％，内阻下降46.55%；电极生物膜主要菌属为Trichococcus（19.68%-74.91%）、Lactococcus（0.33%-17.56%）和Comamonas（0.13%-8.46%），而Comamonas和Shinella可能作为极性反转菌株，得到富集；（2）从极性反转MFC中分离筛选得到两菌株（pr-2和pr-3），其细胞形态均为杆状，pr-2菌株可产生一对氧化还原峰，说明其可能作为电化学活性菌并产生电化学活性物质；pr-3可能因生物膜电容性影响，未出现氧化还原峰，但其产电能力较好。（3）向极性反转MFC中添加核黄素、AQDS和亚甲基蓝三种氧化还原介体，均增强反应器产电能力，但活性电位不同，可以通过添加活性物质调节产电菌自身代谢获能及输出电能。本项目的成功实施，深化了对极性反转过程的认识，为极性反转菌的潜在应用提供了理论基础。