微生物电解池阳极生物膜功能菌群构建及群落特征分析

【目的】微生物电解电池(MEC)是近几年快速发展的利用电极呼吸微生物快速降解有机质,通过较小的辅助外加电压直接生成氢气的新工艺。MEC能够有效地富集高效率电子传递功能菌群,是未来工艺放大和快速启动的关键。【方法】采用不同驯化方法构建MEC电极微生物菌群,通过单链构象多肽性技术(Single-strand conformation poly-morphism,SSCP)快速检测分析启动后电子传递功能菌群特征。【结果】阳极生物膜接种MEC可以实现2 d的快速启动,库仑效率达到20%以上,7 d获得稳定产氢,氢气转化率达到30%,能量回收效率达到90%以上。通过SSCP群落分析发现,采用微生物燃料电池阳极生物膜构建的MEC主要电子传递功能相关的菌群包括Pseudomonas sp.、Flavobacterium sp.、Ochrobactrum sp.,而直接由产氢MEC阳极生物膜新启动的MEC功能菌群组成丰度更大,包括电子传递效能更高的Desulfovibrio、Pseudomonas和Shewanella成为主要优势电子传递菌群。通过稳定产氢运行,MEC阳极生物膜优势菌群中存在的较大比例的厌氧菌与电子传递辅助菌对体系的快速稳定运行十分重要。【结论】与MFC阳极生物膜相比,MEC生物膜作为启动菌源能够获得多样性更丰富的电极功能菌群,其库仑效率和产氢效率更具优势。     

微生物燃料电池阳极产电微生物和阴极受体特性及研究进展

介绍微生物燃料电池的基本工作原理。根据电子传递方式阳极产电微生物分为无需中间体微生物和需中间体微生物。对阴极进行不同反应所涉及的最终电子受体进行了概述,并展望了微生物燃料电池的应用前景。     

微生物燃料电池中产电微生物的研究进展

产电微生物是微生物燃料电池系统的核心组成, 本文从生物学角度介绍了几种产电微生物的分类学地位、形态特征、生理生化特征及在微生物燃料电池中的产电机理和产电能力, 分析了利用产电微生物进行废水处理同时生物发电的应用前景, 提出产电微生物在MFC系统中的进一步研究方向为微生物的富集、驯化、改造和多种菌种优化组合等。     

利用异化金属还原菌构建含糖微生物燃料电池

环境中的一些微生物通过还原金属氧化物进行无氧呼吸,而石墨电极与金属氧化物相似,也可以作为这类微生物呼吸作用的最终电子受体,利用这类微生物构建微生物燃料电池,以糖类物质为燃料,对电池产电情况、产电原理进行研究。实验结果表明,以Rhodoferaxferrireducens为产电微生物,在外接电阻510Ω条件下,以葡萄糖为燃料,常温下产生的电流密度达158mAm2(平台电压为0.46V,电极有效接触表面积为57cm2),且循环性能良好。更换燃料为其它糖,发现微生物可以利用多种糖进行产电;通过SEM观察发现大量微生物吸附在石墨电极上,用Bradford法对运行20d后电池的细胞量进行定量,测得悬浮细胞蛋白浓度为140mgL,吸附在电极上的生物量为1180mgm2。通过数据采集分析和细菌还原实验,发现吸附在电极上的微生物对电压的产生贡献最大,具有电化学和生物学活性;悬浮细胞对产电贡献很小,不具有电化学和生物学活性。     

产电微生物及微生物燃料电池最新研究进展

新型产电微生物(Electricigens)的发现,使得微生物燃料电池概念的内涵发生了根本性的变化,展现了广阔的应用前景。这种微生物能够以电极作为唯一电子受体,把氧化有机物获得的电子通过电子传递链传递到电极产生电流,同时微生物从中获得能量而生长。这种代谢被认为是一种新型微生物呼吸方式。以这种新型微生物呼吸方式为基础的微生物燃料电池可以同时进行废水处理和生物发电,有望可以把废水处理发展成一个有利可图的产业,是MFC最有发展前景的方向。     

微生物燃料电池中阳极产电微生物的研究进展

微生物燃料电池（MFC）是利用阳极产电微生物为催化剂降解有机废物直接将化学能转化为电能的装置。在MFC系统中,产电微生物是影响产电性能的核心要素之一。介绍了MFC中产电微生物的最新研究现状,详细讨论了产电微生物的种类、产电机理和产电能力．为产电微生物的富集、驯化、改造和多种菌种优化组合提供思路。     

微生物燃料电池中假单胞菌F026的产电性能研究

基于微生物燃料电池的反应装置,从污水处理厂曝气池的污泥中通过富集,筛选和基于16S rRNA基因序列的系统发育分析等手段驯化出1株高效产电假单胞菌F026。以F026为阳极产电菌制作微生物燃料电池,考察了底物种类、温度和p H值等因素对微生物燃料电池产电性能的影响。结果表明,F026最适合在以可溶性淀粉为底物,p H为中性偏碱性,温度在30~35℃的环境下生长。在此条件下,微生物燃料电池的最高电压达到500 m V,体积功率密度达到2 W/m3。     

微生物燃料电池中产电微生物的研究进展

微生物燃料电池(Microbial fuel cell,MFC)作为一种新型的环境治理和能源技术,目前已得到研究者们的广泛关注。微生物燃料电池是一种利用微生物将有机物中的化学能转化成电能的装置,产电微生物作为生物催化剂,对微生物燃料电池的发展至关重要。不同种类的产电微生物,其电子转移机制与能力有所差异,直接影响MFC的产电性能,从而决定MFC在工程实践中的性能与应用。任何含有大量微生物的废水、污泥、沉积物都可以作为产电微生物的筛选来源,尝试从不同环境条件下分离筛选高效产电微生物有望促进MFC的进一步完善,从而加速其在环境中的应用。通过对微生物燃料电池的发展、产电微生物种类及其电子传递机制等进行总结分析,综述了MFC中产电微生物的最新研究进展,包括产电微生物的筛选方法、种类以及技术研究等,最后展望了今后在产电微生物方面的主要研究方向及MFC的发展前景,以期为产电微生物的的筛选和应用奠定相应的理论基础及提供思路。     

一株耐盐产电菌Shewanella algae E-1的分离及其产电特性分析

【背景】产电微生物的种类和电化学活性机制对微生物燃料电池的产电性能有着重要的影响。【目的】从海水中分离获得一株耐盐产电微生物,研究其产电特性并鉴定种属信息。【方法】以取自南海的海水为接种液启动并运行阳极液中含有不同盐浓度的微生物燃料电池,从富集的阳极生物膜上分离得到一株纯培养的微生物菌株,命名为E-1。通过接种于阳极液中添加不同盐浓度的微生物燃料电池中对其产电特性进行分析,并利用形态学观察、Biolog分析和16SrRNA基因序列比对相结合的方法进行种属鉴定。【结果】菌株E-1在无外源添加和外源添加6.6%NaCl条件下产生的功率密度分别为51.69 m W/m2和26.56 m W/m2,这与其良好的耐盐能力相关。菌株E-1被鉴定为海藻希瓦氏菌(Shewanella algae),表现出多样的底物利用能力,生长的温度范围为25-40°C,pH范围为5.0-10.0。【结论】这是首次对Shewanella algae种内微生物产电性能及其在微生物燃料电池中应用的报道,丰富了产电微生物的多样性,菌株E-1能够在较高盐浓度条件下表现出良好的产电性能,为微生物燃料电池在海水资源化处理方面的应用提供新的实验材料。     

驯化对生物阴极微生物燃料电池中阴极微生物群落多样性的影响

【背景】生物阴极微生物燃料电池因其构造成本低和阴极可持续性发展的优点而成为一种很有前途的废水处理系统,但阴极微生物的氧化还原性能限制了其在实际应用中的推广。【目的】为了提高生物阴极的性能,需要深入了解影响阴极氧化还原性能的微生物群落。【方法】利用16S rRNA基因高通量测序技术分析对比原始接种污泥样品和驯化后阴极电极上生物膜样品多样性及结构变化。【结果】测序结果表明,原始接种污泥样品与驯化后阴极电极生物膜样品中微生物群落种类和结构存在显著差异,驯化后阴极电极生物膜样品中变形菌门(Proteobacteria)、γ-变形菌纲(Gammaproteobacteria)和特吕珀菌属(Trueperaceae)相对丰度比例高于原始污泥样品,成为优势菌群。【结论】驯化对系统阴极电极生物膜群落影响显著,随着产电量的输出,优势菌群不断富集,最终形成一个适应该实验环境下的新的微生物群落。对优势菌群结构和变化进行探讨,为生物阴极的研究补充更多生物学方面的理论基础。     

The effect of flavin electron shuttles in microbial fuel cells current production

The effect of electron shuttles on electron transfer to microbial fuel cell (MFC) anodes was studied in systems where direct contact with the anode was precluded. MFCs were inoculated with Shewanella cells, and flavins used as the electron shuttling compound. In MFCs with no added electron shuttles, flavin concentrations monitored in the MFCs' bulk liquid increased continuously with FMN as the predominant flavin. The maximum concentrations were 0.6 μM for flavin mononucleotide and 0.2 μM for riboflavin. In MFCs with added flavins, micro-molar concentrations were shown to increase current and power output. The peak current was at least four times higher in MFCs with high concentrations of flavins (4.5–5.5 μM) than in MFCs with low concentrations (0.2–0.6 μM). Although high power outputs (around 150 mW/m²) were achieved in MFCs with high concentrations of flavins, a Clostridium-like bacterium along with other reactor limitations affected overall coulombic efficiencies (CE) obtained, achieving a maximum CE of 13%. Electron shuttle compounds (flavins) permitted bacteria to utilise a remote electron acceptor (anode) that was not accessible to the cells allowing current production until the electron donor (lactate) was consumed.     

Microbial fuel cell (MFC) power performance improvement through enhanced microbial electrogenicity

Within the past 5?years, tremendous advances have been made to maximize the performance of microbial fuel cells (MFCs) for both “clean” bioenergy production and bioremediation. Most research efforts have focused on parameters including (i) optimizing reactor configuration, (ii) electrode construction, (iii) addition of redox-active, electron donating mediators, (iv) biofilm acclimation and feed nutrient adjustment, as well as (v) other parameters that contribute to enhanced MFC performance. To date, tremendous advances have been made, but further improvements are needed for MFCs to be economically practical. In this review, the diversity of electrogenic microorganisms and microbial community changes in mixed cultures are discussed. More importantly, different approaches including chemical/genetic modifications and gene regulation of exoelectrogens, synthetic biology approaches and bacterial community cooperation are reviewed. Advances in recent years in metagenomics and microbiomes have allowed researchers to improve bacterial electrogenicity of robust biofilms in MFCs using novel, unconventional approaches. Taken together, this review provides some important and timely information to researchers who are examining additional means to enhance power production of MFCs.     

New exoelectrogen Citrobacter sp. SX-1 isolated from a microbial fuel cell

Aims: Isolation, identification and characterization of a new exoelectrogenic bacterium from a microbial fuel cell (MFC). Methods and Results: Exoelectrogenic bacterial strain SX‐1 was isolated from a mediator‐less MFC by conventional plating techniques with ferric citrate as electron acceptor under anaerobic condition. Phylogenetic analysis of the 16S rDNA sequence revealed that it was related to the members of Citrobacter genus with Citrobacter sp. sdy‐48 being the most closely related species. The bacterial strain SX‐1 produced electricity from citrate, acetate, glucose, sucrose, glycerol and lactose in MFCs with the highest current density of 205 mA m^?2 generated from citrate. Cyclic voltammetry analysis indicated that membrane‐associated proteins may play an important role in facilitating the electrons transferring from bacteria to electrode. Conclusions: This is the first study that demonstrates that Citrobacter species can transfer electrons to extracellular electron acceptors. Citrobacter strain SX‐1 is capable of generating electricity from a wide range of substrates in MFCs. Significance and Impact of the Study: This finding increases the known diversity of power generating exoelectrogens and provided a new strain to explore the mechanisms of extracellular electron transfer from bacteria to electrode. The wide range of substrate utilization by SX‐1 increases the application potential of MFCs in renewable energy generation and waste treatment.     

Change in microbial communities in acetate- and glucose-fed microbial fuel cells in the presence of light

Power densities produced by microbial fuel cells (MFCs) in natural systems are changed by exposure to light through the enrichment of photosynthetic microorganisms. When MFCs with brush anodes were exposed to light (4000 lx), power densities increased by 8–10% for glucose-fed reactors, and 34% for acetate-fed reactors. Denaturing gradient gel electrophoresis (DGGE) profiles based on the 16S rRNA gene showed that exposure to high light levels changed the microbial communities on the anodes. Based on 16S rRNA gene clone libraries of light-exposed systems the anode communities using glucose were also significantly different than those fed acetate. Dominant bacteria that are known exoelectrogens were identified in the anode biofilm, including a purple nonsulfur (PNS) photosynthetic bacterium, Rhodopseudomonas palustris, and a dissimilatory iron-reducing bacterium, Geobacter sulfurreducens. Pure culture tests confirmed that PNS photosynthetic bacteria increased power production when exposed to high light intensities (4000 lx). These results demonstrate that power production and community composition are affected by light conditions as well as electron donors in single-chamber air-cathode MFCs.     

Effect of different acclimation methods on the performance of microbial fuel cells using phenol as substrate

Single-chamber microbial fuel cells (MFCs) with air-cathode were constructed. MFCs were fed different feedstocks during their inoculation, their role on phenol degradation and MFC performance were investigated. The results showed that the MFC inoculated using glucose exhibited the highest power density (31.3 mW m^?2) when phenol was used as the sole substrate for MFC. The corresponding biodegradation kinetic constant was obtained at 0.035 h^?1, at an initial phenol concentration of 600 mg L^?1. Moreover, the phenol degradation rates in this MFC with closed circuit were 9.8–16.5 % higher than those in MFC with opened circuit. The cyclic voltammograms revealed a different electrochemical activity of the anode biofilms in the MFC, and this led to differences in performance of the MFCs with phenol as sole substrate. These results demonstrated that phenol degradation and power production are affected by current generation and type of acclimation.     

Improvement of a microbial fuel cell performance as a BOD sensor using respiratory inhibitors

Studies were made to improve the performance of a microbial fuel cell (MFC) as a biochemical oxygen demand (BOD) sensor. The signal from MFCs decreased in the presence of electron acceptors of higher redox potential such as nitrate and oxygen. The addition of azide and cyanide did not change the signal in the absence of the electron acceptors. The respiratory inhibitors eliminated the inhibitory effects of the electron acceptors on the current generation from MFCs. Similar results were obtained using oligotrophic MFCs fed with an environmental sample that contained nitrate. The use of the respiratory inhibitors is therefore recommended for the accurate BOD measurement of environmental samples containing nitrate and/or oxygen with an MFC-type BOD sensor.     

The outer membrane protein Omp35 affects the reduction of Fe(III), nitrate,and fumarate by <Emphasis Type="Italic">Shewanella oneidensis</Emphasis> MR-1

Background  

Shewanella oneidensis MR-1 uses several electron acceptors to support anaerobic respiration including insoluble species such as iron(III) and manganese(IV) oxides, and soluble species such as nitrate, fumarate, dimethylsulfoxide and many others. MR-1 has complex branched electron transport chains that include components in the cytoplasmic membrane, periplasm, and outer membrane (OM). Previous studies have implicated a role for anaerobically upregulated OM electron transport components in the use of insoluble electron acceptors, and have suggested that other OM components may also contribute to insoluble electron acceptor use. In this study, the role for an anaerobically upregulated 35-kDa OM protein (Omp35) in the use of anaerobic electron acceptors was explored.     

Electricity-producing bacterial communities in microbial fuel cells

Microbial fuel cells (MFCs) are not yet commercialized but they show great promise as a method of water treatment and as power sources for environmental sensors. The power produced by these systems is currently limited, primarily by high internal (ohmic) resistance. However, improvements in the system architecture will soon result in power generation that is dependent on the capabilities of the microorganisms. The bacterial communities that develop in these systems show great diversity, ranging from primarily delta-Proteobacteria that predominate in sediment MFCs to communities composed of alpha-, beta-, gamma- or delta-Proteobacteria, Firmicutes and uncharacterized clones in other types of MFCs. Much remains to be discovered about the physiology of these bacteria capable of exocellular electron transfer, collectively defined as a community of "exoelectrogens". Here, we review the microbial communities found in MFCs and the prospects for this emerging bioenergy technology.     

Microbial fuel cells: novel biotechnology for energy generation

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy from biodegradable, reduced compounds. MFCs function on different carbohydrates but also on complex substrates present in wastewaters. As yet there is limited information available about the energy metabolism and nature of the bacteria using the anode as electron acceptor; few electron transfer mechanisms have been established unequivocally. To optimize and develop energy production by MFCs fully this knowledge is essential. Depending on the operational parameters of the MFC, different metabolic pathways are used by the bacteria. This determines the selection and performance of specific organisms. Here we discuss how bacteria use an anode as an electron acceptor and to what extent they generate electrical output. The MFC technology is evaluated relative to current alternatives for energy generation.     

Electrochemical analysis of Clostridium propionicum and its acrylic acid production in microbial fuel cells

Currently, acrylic acid is produced at a low yield by the resting cells of Clostridium propionicum with the supplement of extra electron acceptors. As an alternative way, acrylic acid production coupled with electricity generation was achieved by C. propionicum‐based microbial fuel cells (MFCs). Electricity was generated in the salt‐bridge MFCs with cysteine and resazurin in the anode chamber as mediators, and K₃Fe(CN)₆ as the cathode electron acceptor. Power generation was 21.78 mW/m² with an internal resistance of 9809 Ω. Cyclic voltammograms indicated the main mechanism of power production was the electron transfer facilitated by mediators in the system. In the salt‐bridge MFC system, 0.694 mM acrylic acid was produced together with electricity generation.