好氧-厌氧混合污泥启动微生物燃料电池产电性能及微生物群落动态特征

【目的】为探讨好氧-厌氧混合污泥启动微生物燃料电池(Microbial fuel cell,MFC)产电性能以及MFC对微生物群落的选择作用,【方法】以乳酸为底物,应用不依赖于培养的微生物分子生物学技术解析单室MFC启动过程中微生物群落的组成和结构动态学特征。【结果】结果表明,MFC经过3个周期启动成功,最高输出电压230 m V。当MFC外电阻为1656Ω时,最大功率密度11.15 W/m3,电池运行稳定。混合污泥启动MFC以后,阳极生物膜微生物群落结构同种泥差异较大,且多样性降低。生物膜中微生物类群按丰度依次为β-变形菌纲(Betaproteobacteria)24.90%、拟杆菌门(Bacteroidetes)21.30%、厚壁菌门(Firmicutes)9.70%、γ-变形菌纲(Gammaproteobacteria)8.50%、δ-变形菌纲(Deltaproteobacteria)7.90%、绿弯菌门(Chloroflexi)4.20%以及α-变形菌纲(Alphaproteobacteria)3.60%。有利于生物膜形成与稳定的动胶菌属(Zoogloea)和不动杆菌属(Acinetobacter)序列丰度分别占生物膜群落的5.00%和3.90%,与MFC产电能力直接相关的地杆菌属(Geobacter)序列由混合污泥中的0.60%上升至阳极生物膜中的2.60%。【结论】本研究表明,MFC阳极生物膜在驯化过程中对污泥中的微生物进行淘汰和选择,最终驯化形成了有利于生物膜形成与稳定、有机物厌氧发酵与产电的微生物菌群。     

微生物燃料电池利用乳酸产电性能与微生物群落分布特征

【目的】为探讨以乳酸为基质的微生物燃料电池(Microbial fuel cell,MFC)产电性能以及微生物群落在阳极膜、悬浮液、阳极沉淀污泥中的分布特征,【方法】试验建立了双室MFC,以乳酸为阳极主要碳源,研究了反应器的启动过程及产电效能,同时以电镜和PCR-变性梯度凝胶电泳(Denaturing gradient gelelectrophoresis,DGGE)技术解析了微生物群落的空间分布特征。【结果】结果表明,反应器启动第7天时外电压达到0.56 V,当外阻为80Ω时,电流密度为415 mA/m2,MFC的功率密度达到最大值82 mW/m2。电镜观察发现大量杆菌附着在阳极表面,结合较为紧密;DGGE图谱显示阳极膜表面微生物与种泥最为相似,与阳极悬浮液、底部沉淀污泥中的主要菌群一致,条带序列与睾丸酮丛毛单胞菌(Comamonas testosteroni)和布氏弓形菌(Arcobacter butzleri)等最为相似。【结论】本研究表明以乳酸为基质MFC可产生较高的功率密度,阳极附着的优势菌与接种污泥来源密切相关。     

关于微生物燃料电池底物的研究进展

近年来,微生物燃料电池已引起了广泛关注,它将低能量废水和木质纤维素生物质等有机废物转化为电能。在将来,微生物电能将成为一种重要的生物能源,因为微生物燃料电池提供了一种复合有机物和可再生生物能源中提取电能的可行性。人们研究了许多物质,以考察其是否能作为微生物电能转化的底物。这些物质包括人工的和天然废物,以及木质纤维素生物质。尽管现在微生物燃料电池提供的电流和功率较低,但是随着技术的发展和对微生物燃料电池系统的深入了解,微生物燃料电池转化的电流和电力将极大增加,从而向世人提供了一种可以将纤维素生物质和废水直接转化为有用能源的有效方法。本文介绍了迄今为止在微生物燃料电池中用到的各种反应底物,并对它们的应用效率和存在的不足进行了分析。     

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。     

高通量测序和DGGE分析土壤微生物群落的技术评价

【目的】比较新一代高通量测序与传统的变性梯度凝胶电泳(Denaturing Gradient Gel Electrophoresis,DGGE)指纹图谱技术,评价两种技术研究土壤微生物群落结构的优缺点。【方法】针对新西兰典型草地和森林土壤,以16S rRNA基因为标靶,通过高通量测序和DGGE技术分析土壤微生物群落的组成、丰度和多样性,比较两种方法在土壤微生物研究中的适用性。【结果】在不同的微生物分类水平,高通量测序草地土壤检测到22门,54纲,60目,131科,350属;而DGGE仅检测到6门,9纲,8目,10科,10属,表明DGGE显著低估了土壤微生物的群落组成。森林土壤也得到了类似规律,高通量测序的检测灵敏度是DGGE的3.8、6.7、6.4、19.2及39.4倍。进一步分析土壤中主要微生物类群的相对丰度,发现分类水平越低,高通量测序与DGGE的结果差异越大,尤其在科和属的水平上差异最大。以高通量测序结果为标准,DGGE明显高估了土壤中大多数微生物类群的相对丰度,最高可达2000倍。两种方法都表明草地土壤的多样性指数高于森林土壤,但DGGE多样性指数的绝对值远低于高通量测序结果。【结论】高通量测序能够较为全面和准确的反映土壤微生物群落结构,而DGGE仅能够反映有限的优势微生物类群,在很大程度上极可能低估土壤微生物的物种组成并高估其丰度。     

纳米材料修饰微生物燃料电池阳极的研究进展

阳极作为微生物燃料电池中的重要组成部分,其性能的高低显著影响着微生物燃料电池的产电性能。纳米材料具有导电性好、表面积大等优良特性。因此,纳米材料修饰阳极能够有效减小电极内阻、增大微生物的粘附量,从而显著提高微生物燃料电池的产电性能。本文首先简要介绍了微生物燃料电池中阳极修饰纳米材料的种类,然后重点归纳了不同纳米材料修饰阳极对微生物燃料电池产电性能的影响及其原因。最后对微生物燃料电池阳极修饰纳米材料和技术进行展望。     

分子生物学技术在肠道微生物研究中的应用进展

肠道微生物与宿主的健康状况息息相关,已成为当今的热点研究领域。随着分子生物学技术的快速发展,高通量测序技术、实时荧光定量PCR技术和PCR-DGGE技术等凭借其高灵敏度、高通量、无需体外培养等优势,为研究微生物结构和功能基因组提供了新方法,并在肠道菌群的研究中应用广泛。本文对这三种分子生物学技术在肠道微生物研究中的应用进行了综述,总结了这三种技术在肠道微生物研究中的应用范围和优缺点,并展望了其在肠道微生物研究中的广阔应用前景。     

双阳极室甲烷微生物燃料电池同步脱氮除硫性能及微生物群落分析

【背景】甲烷厌氧氧化(anaerobic oxidation of methane, AOM)包含反硝化型甲烷厌氧氧化和硫酸盐还原型甲烷厌氧氧化。目前,人们向水体中排放过量的含氮及含硫污染物,引起了严重的环境污染和生态破坏。【目的】利用甲烷厌氧氧化微生物燃料电池(microbial fuel cell, MFC)研究同步脱氮除硫耦合反应机理及反应过程中微生物的多样性信息。【方法】构建了3个微生物燃料电池(N-S-MFC、N-MFC、S-MFC),以甲烷作为唯一碳源,探究其同步脱氮除硫性能,并采用16S rRNA基因高通量测序技术对微生物群落结构进行分析。【结果】N-S-MFC中硝酸盐和硫酸盐的去除率分别为90.91%和18.46%。阳极室中微生物的相对丰度提高,与反硝化及硫酸盐还原菌相关的微生物大量富集,如门水平上拟杆菌门(Bacteroidota)、厚壁菌门(Firmicutes)和脱硫杆菌门(Desulfobacterota),同时属水平上Methylobacterium＿Methylorubrum、Methylocaldum、Methylomonas等常见的甲烷氧化菌增多。【结论...     

不同底物对海洋混合菌群产氢的影响

将采自天津潮间带的污泥进行热休克处理,厌氧条件下富集混合菌群进行产氢试验。混合菌群分别接种于含葡萄糖、蔗糖、乳糖、淀粉和蛋白胨的培养液中,测定不同底物培养条件下混合菌群产氢量及菌群组成。结果表明,以蔗糖为底物时,混合菌群产氢量最高,为（787±24）mL／L;混合菌群以葡糖糖、乳糖和淀粉为底物时,产氢量依次为（530±20）、（46±5）和（455±35）mL／L;混合菌群不能利用蛋白胨为底物产氢。变性梯度凝胶电泳（DGGE）分析不同底物培养条件下的产氢混合菌群组成。混合菌群16S rRNA基因的DGGE分离结果表明,在蛋白胨培养条件下,混合菌群没有能够形成优势菌,其他底物培养时,混合菌群的优势菌是Clostridium sp．。     

微生物燃料电池降解苯酚过程中微电场对阴极微生物多样性的影响

[背景]苯酚废水作为一种毒性强、难降解的废水而备受关注.目前,微生物燃料电池(microbial fuel cell,MFC)已经广泛用于苯酚废水的降解,MFC的产电效果和苯酚的降解效率与反应器内的微生物群落有着密切关系.[目的]为了提高MFC的产电效果及对有害物质的降解能力,需要对MFC中苯酚的降解和微生物群落结构进...     

Convergent development of anodic bacterial communities in microbial fuel cells

Microbial fuel cells (MFCs) are often inoculated from a single wastewater source. The extent that the inoculum affects community development or power production is unknown. The stable anodic microbial communities in MFCs were examined using three inocula: a wastewater treatment plant sample known to produce consistent power densities, a second wastewater treatment plant sample, and an anaerobic bog sediment. The bog-inoculated MFCs initially produced higher power densities than the wastewater-inoculated MFCs, but after 20 cycles all MFCs on average converged to similar voltages (470±20 mV) and maximum power densities (590±170 mW m⁻²). The power output from replicate bog-inoculated MFCs was not significantly different, but one wastewater-inoculated MFC (UAJA3 (UAJA, University Area Joint Authority Wastewater Treatment Plant)) produced substantially less power. Denaturing gradient gel electrophoresis profiling showed a stable exoelectrogenic biofilm community in all samples after 11 cycles. After 16 cycles the predominance of Geobacter spp. in anode communities was identified using 16S rRNA gene clone libraries (58±10%), fluorescent in-situ hybridization (FISH) (63±6%) and pyrosequencing (81±4%). While the clone library analysis for the underperforming UAJA3 had a significantly lower percentage of Geobacter spp. sequences (36%), suggesting that a predominance of this microbe was needed for convergent power densities, the lower percentage of this species was not verified by FISH or pyrosequencing analyses. These results show that the predominance of Geobacter spp. in acetate-fed systems was consistent with good MFC performance and independent of the inoculum source.     

Microbial communities and electrochemical performance of titanium-based anodic electrodes in a microbial fuel cell

Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species.     

Electricity generation and microbial community response to substrate changes in microbial fuel cell

The effect of substrate changes on the performance and microbial community of two-chamber microbial fuel cells (MFCs) was investigated in this study. The MFCs enriched with a single substrate (e.g., acetate, glucose, or butyrate) had different acclimatization capability to substrate changes. The MFC enriched with glucose showed rapid and higher power generation, when glucose was switched with acetate or butyrate. However, the MFC enriched with acetate needed a longer adaptation time for utilizing glucose. Microbial community was also changed when the substrate was changed. Clostridium and Bacilli of phylum Firmicutes were detected in acetate-enriched MFCs after switching to glucose. By contrast, Firmicutes completely disappeared and Geobacter-like species were specifically enriched in glucose-enriched MFCs after feeding acetate to the reactor. This study further suggests that the type of substrate fed to MFC is a very important parameter for reactor performance and microbial community, and significantly affects power generation in MFCs.     

Anode microbial communities produced by changing from microbial fuel cell to microbial electrolysis cell operation using two different wastewaters

Conditions in microbial fuel cells (MFCs) differ from those in microbial electrolysis cells (MECs) due to the intrusion of oxygen through the cathode and the release of H₂ gas into solution. Based on 16S rRNA gene clone libraries, anode communities in reactors fed acetic acid decreased in species richness and diversity, and increased in numbers of Geobacter sulfurreducens, when reactors were shifted from MFCs to MECs. With a complex source of organic matter (potato wastewater), the proportion of Geobacteraceae remained constant when MFCs were converted into MECs, but the percentage of clones belonging to G. sulfurreducens decreased and the percentage of G. metallireducens clones increased. A dairy manure wastewater-fed MFC produced little power, and had more diverse microbial communities, but did not generate current in an MEC. These results show changes in Geobacter species in response to the MEC environment and that higher species diversity is not correlated with current.     

Electricity generation using p-nitrophenol as substrate in microbial fuel cell

The cell voltage and degradation rate of p-nitrophenol (PNP) were monitored in a two-chambered microbial fuel cell (MFC) system. Degradation metabolites in the anode solution of MFC were analyzed by gas chromatography–mass spectrometry (GC–MS). PNP was used as substrate by the MFC that was inoculated with anaerobic sludge. The results showed that electricity output increased with the PNP concentration increased, the MFC displayed a maximum power density of 1.778 mW m⁻² and a maximum PNP degradation rate of 64.69% when PNP was used as a sole substrate. However, the cell voltage and the PNP degradation rate with sodium acetate (402.3 mV and 95.96%) were higher than those fed with glucose (341.9 mV and 83.51%) when glucose and sodium acetate were used as a substrate, respectively. Furthermore, GC–MS analysis showed that the PNP was biodegraded completely after 142 h in the MFC. These results demonstrate that PNP can be used for electricity generation in MFC for practical applications of wastewater treatment.     

Response of marine microbial communities to anthropogenic stress

Marine microbial communities adapt rapidly to changingenvironmental conditions, including anthropogenicstress. Adaptation involves a wide range ofstrategies, including, (a) formation of resistant,dormant stages, (b) initiation of repair mechanisms, (c)immobilization of toxic chemicals, (d) active transportof chemicals out of the cell, (e) use of contaminantchemicals as carbon or energy sources, and (f)transformation of contaminants to less toxic or morevolatile forms.Adaptation responses are generally plasmid- orchromosomally-mediated and controlled throughinduction or derepression of a variety of biochemicalpathways. Characterization of microbial communityresponses at the molecular level provides biomarkersof contaminant exposure which in turn may be used toprovide an overall picture of ecosystem health. Thisreview will discuss the interactions betweenmicroorganisms and environmental contaminants and thepotential use of microbial biomarkers to assess thehealth of the microbial ecosystem.     

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.     

Importance of temperature and anodic medium composition on microbial fuel cell (MFC) performance

The performance of a microbial fuel cell (MFC) was investigated at different temperatures and anodic media. A lag phase of 30 h occurred at 30 degrees C which was half that at room temperature (22 degrees C). The maximum power density at 30 degrees C was 70 mW/m(2) and at 22 degrees C was 43 mW/m(2). At 15 degrees C, no successful operation was observed even after several loadings for a long period of operation. Maximum power density of 320 mW/m(2) was obtained with wastewater medium containing phosphate buffer (conductivity: 11.8 mS/cm), which was approx. 4 times higher than the value without phosphate additions (2.89 mS/cm).     

Performance of microbial fuel cell in response to change in sludge loading rate at different anodic feed pH

Performance of two dual chambered mediator-less microbial fuel cells (MFCs) was evaluated at different sludge loading rate (SLR) and feed pH. Optimum performance in terms of organic matter removal and power production was obtained at the SLR of 0.75 kg COD kg VSS⁻¹ d⁻¹. Maximum power density of 158 mW/m² and 600 mW/m² was obtained in MFC-1 (feed pH 6.0) and MFC-2 (feed pH 8.0), respectively. Internal resistance of the cell decreased with increase in SLR. When operated only with biofilm on anode, the maximum power density was 109.5 mW/m² in MFC-1 and 459 mW/m² in MFC-2, which was, respectively, 30% and 23.5% less than the value obtained in MFC-1 and MFC-2 at SLR of 0.75 kg COD kg VSS⁻¹ d⁻¹. Maximum volumetric power of 15.51 W/m³ and 36.72 W/m³ was obtained in MFC-1 and MFC-2, respectively, when permanganate was added as catholyte. Higher feed pH (8.0) favoured higher power production.     

Electrocatalytic activity of anodic biofilm responses to pH changes in microbial fuel cells

This study investigates the effects of anodic pH on electricity generation in microbial fuel cells (MFCs) and the intrinsic reasons behind them. In a two-chamber MFC, the maximum power density is 1170 ± 58 mW m⁻² at pH 9.0, which is 29% and 89% higher than those working at pH 7.0 and 5.0, respectively. Electrochemical measurements reveal that pH affects the electron transfer kinetics of anodic biofilms. The apparent electron transfer rate constant (k_app) and exchange current density (i₀) are greater whereas the charge transfer resistance (R_ct) is smaller at pH 9.0 than at other conditions. Scanning electron microscopy verifies that alkaline conditions benefit biofilm formation in MFCs. These results demonstrate that electrochemical interactions between bacteria and electrodes in MFCs are greatly enhanced under alkaline conditions, which can be one of the important reasons for the improved MFC output.