Microbial community differences between propionate-fed microbial fuel cell systems under open and closed circuit conditions (original) (raw)
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Bacterial community structure, compartmentalization and activity in a microbial fuel cell
Journal of Applied Microbiology, 2006
Aims: To characterize bacterial populations and their activities within a microbial fuel cell (MFC), using cultivation-independent and cultivation approaches. Methods and Results: Electron microscopic observations showed that the fuel cell electrode had a microbial biofilm attached to its surface with loosely associated microbial clumps. Bacterial 16S rRNA gene libraries were constructed and analysed from each of four compartments within the fuel cell: the planktonic community; the membrane biofilm; bacterial clumps (BC) and the anode biofilm. Results showed that the bacterial community structure varied significantly between these compartments. It was observed that Gammaproteobacteria phylotypes were present at higher numbers within libraries from the BC and electrode biofilm compared with other parts of the fuel cell. Community structure of the MFC determined by analyses of bacterial 16S rRNA gene libraries and anaerobic cultivation showed excellent agreement with community profiles from denaturing gradient gel electrophoresis (DGGE) analysis. Conclusions: Members of the family Enterobacteriaceae, such as Klebsiella sp. and Enterobacter sp. and other Gammaproteobacteria with Fe(III)-reducing and electrochemical activity had a significant potential for energy generation in this system. Significance and Impact of the Study: This study has shown that electrochemically active bacteria can be enriched using an electrochemical fuel cell.
Journal of Bioscience and Bioengineering, 2013
It is important for practical use of microbial fuel cells (MFCs) to not only develop electrodes and proton exchange membranes but also to understand the bacterial community structure related to electricity generation. Four lactate fed MFCs equipped with different membrane electrode assemblies (MEAs) were constructed with paddy field soil as inoculum. The MEAs significantly affected the electricity-generating properties of the MFCs. MEA-I was made with Nafion 117 solution and the other MEAs were made with different configurations of three kinds of polymers. MFC-I equipped with MEA-I exhibited the highest performance with a stable current density of 55 ± 3 mA m L2 . MFC-III equipped with MEA-III with the highest platinum concentration, exhibited the lowest performance with a stable current density of 1.7 ± 0.1 mA m L2 . SEM observation revealed that there were cracks on MEA-III. These results demonstrated that it is significantly important to prevent oxygen-intrusion for improved MFC performance. By comparing the data of DGGE and phylogenetic analyzes, it was suggested that the dominant bacterial communities of MFC-I were constructed with lactate-fermenters and Fe(III)-reducers, which consisted of bacteria affiliated with the genera of Enterobacter, Dechlorosoma, Pelobacter, Desulfovibrio, Propioniferax, Pelosinus, and Firmicutes. A bacterium sharing 100% similarity to one of the DGGE bands was isolated from MFC-I. The 16S rRNA gene sequence of the isolate shared 98% similarity to grampositive Propioniferax sp. P7 and it was confirmed that the isolate produced electricity in an MFC. These results suggested that these bacteria are valuable for constructing the electron transfer network in MFC.
Journal of Water Process Engineering, 2020
This study investigated the microbial community structure on the anode surface of four dual chamber bioelectrochemical systems. These systems were Microbial Fuel Cell (MFC) and Microbial Electrolysis Cell (MEC). The systems were inoculated with activated sludge and operated for electricity generation/hydrogen (H 2) production, and phosphorus (P) recovery. The MFC achieved a maximum power output of 185 mW/m 2 (1.62 kW h/m 2), whilst the MEC achieved a maximum H 2 production rate of 0.28 m 3-H 2 /m 3-d. Results from Illumina highthroughput sequencing of 16S rRNA genes showed that the microbial community structure of the MFCs was more diverse than that of the MECs, and this variation may be attributed to the differences in the operational conditions of the MFC and the MEC. MFC and MEC shared the same dominant bacterial phyla; Bacteroidetes, Proteobacteria and Firmicutes, with the most abundant bacterial genus in both systems belonging to Desulfovibrio. However, the abundance of Desulfovibrio in the MECs (13.2 ± 0.7 %) was greater than that in the MFCs (4.25 ± 0.2 %).
Applied Microbiology and Biotechnology, 2007
Microbial fuel cells (MFCs) harness the electrochemical activity of certain microbes for the production of electricity from reduced compounds. Characterizations of MFC anode biofilms have collectively shown very diverse microbial communities, raising ecological questions about competition and community succession within these anodereducing communities. Three sets of triplicate, two-chamber MFCs inoculated with anaerobic sludge and differing in energy sources (acetate, lactate, and glucose) were operated to explore these questions. Based on 16S rDNA-targeted denaturing gradient gel electrophoresis (DGGE), all anode communities contained sequences closely affiliated with Geobacter sulfurreducens (>99% similarity) and an uncultured bacterium clone in the Bacteroidetes class (99% similarity). Various other Geobacter-like sequences were also enriched in most of the anode biofilms. While the anode communities in replicate reactors for each substrate generally converged to a reproducible community, there were some variations in the relative distribution of these putative anode-reducing Geobacter-like strains. Firmicutes were found only in glucose-fed MFCs, presumably serving the roles of converting complex carbon into simple molecules and scavenging oxygen. The maximum current density in these systems was negatively correlated with internal resistance variations among replicate reactors and, likely, was only minimally affected by anode community differences in these two-chamber MFCs with high internal resistance.
Anodic and cathodic microbial communities in single chamber microbial fuel cells
New Biotechnology, 2015
Microbial fuel cells (MFCs) are a rapidly growing technology for energy production from wastewater and biomasses. In a MFC, a microbial biofilm oxidizes organic matter and transfers electrons from reduced compounds to an anode as the electron acceptor by extracellular electron transfer (EET). The aim of this work was to characterize the microbial communities operating in a Single Chamber Microbial Fuel Cell (SCMFC) fed with acetate and inoculated with a biogas digestate in order to gain more insight into anodic and cathodic EET. Taxonomic characterization of the communities was carried out by Illumina sequencing of a fragment of the 16S rRNA gene. Microorganisms belonging to Geovibrio genus and purple non-sulfur (PNS) bacteria were found to be dominant in the anodic biofilm. The alkaliphilic genus Nitrincola and anaerobic microorganisms belonging to Porphyromonadaceae family were the most abundant bacteria in the cathodic biofilm.
Convergent development of anodic bacterial communities in microbial fuel cells
The ISME Journal, 2012
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 À 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.
Electricity-producing bacterial communities in microbial fuel cells
Trends in Microbiology, 2006
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 d-Proteobacteria that predominate in sediment MFCs to communities composed of a-, b-, g-or d-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.
Energy, 2016
Microbial Fuel Cells (MFC) are bio-electrochemical systems that convert chemical energy into electrical energy from the respiratory metabolic profit of electrochemically active bacteria. In order to contribute to a greater understanding regarding the MFCs performance, real-time quantitative PCR was applied to determining typical planktonic bacteria in the production of electricity in MFCs, evaluating their relations with different carbon-based anode materials: carbon felt (C-FELT), carbon felt with polyaniline (C-PANI) and carbon-coated Berl saddles (C-SADDLES). Bacteria distribution among the three different MFC anode materials was evaluated: statistically significant differences were detectable for total bacteria (p < 0.01), Geobacter (p < 0.05) and Shewanella (p < 0.05), due to a greater abundance in C-FELT anode MFC. Significant difference (p < 0.001) was shown for maximum power density: C-PANI showed a maximum power density of 28.5 W/m3 with respect to C-FELT (4.7 W/m3) and C-SADDLES (4.6 W/m3). In general the largest electrochemically active planktonic microbes was present in the C-FELT while the best carbon-based anode materials results C-PANI.
ChemSusChem, 2021
In memory of Dr. Alessandra Colombo A cross-laboratory study on microbial fuel cells (MFC) which involved different institutions around the world is presented. The study aims to assess the development of autochthone microbial pools enriched from domestic wastewater, cultivated in identical single-chamber MFCs, operated in the same way, thereby approaching the idea of developing common standards for MFCs. The MFCs are inoculated with domestic wastewater in different geographic locations. The acclimation stage and, consequently, the startup time are longer or shorter depending on the inoculum, but all MFCs reach similar maximum power outputs (55 � 22 μW cm À 2) and COD removal efficiencies (87 � 9 %), despite the diversity of the bacterial communities. It is inferred that the MFC performance starts when the syntrophic interaction of fermentative and electrogenic bacteria stabilizes under anaerobic conditions at the anode. The generated power is mostly limited by electrolytic conductivity, electrode overpotentials, and an unbalanced external resistance. The enriched microbial consortia, although composed of different bacterial groups, share similar functions both on the anode and the cathode of the different MFCs, resulting in similar electrochemical output.