Microbial solar cells: applying photosynthetic and electrochemically active organisms

Microbial solar cells (MSCs) are recently developed technologies utilizing solar energy to produce electricity or chemicals. MSCs use photoautotrophic microorganisms or higher plants to harvest solar energy, and use electrochemically active microorganisms in the bioelectrochemical system to generate electrical current. Here, we review the principles and performance of various MSCs, in an effort to identify the most promising systems as well as the bottlenecks and potential solutions towards „real life. MSC application. We give an outlook on future applications based on the intrinsic advantages of MSCs, showcasing specifically how these living energy systems can facilitate the development of an electricity-producing green roof.This is a "Post-Print" accepted manuscript, which has been published in "Trends in Biotechnology". This version is distributed under the Creative Commons Attribution 3.0 Netherlands License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Please cite this publication as follows: 2011 Trends in Biotechnology Microbial solar cells: applying photosynthetic and electrochemically active organisms. David P.B.T.B. Strik, Ruud A. Timmers, Marjolein Helder, Kirsten J.J. Steinbusch, Hubertus V.M. Hamelers, , Cees J.N. Buisman. Trends in Biotechnology 29 (1), 41-49 You can download the published version at: http://dx.doi.org/10.1016/j.tibtech.2010.10.00

Long-term performance of a plant microbial fuel cell with Spartina anglica

The plant microbial fuel cell is a sustainable and renewable way of electricity production. The plant is integrated in the anode of the microbial fuel cell which consists of a bed of graphite granules. In the anode, organic compounds deposited by plant roots are oxidized by electrochemically active bacteria. In this research, salt marsh species Spartina anglica generated current for up to 119 days in a plant microbial fuel cell. Maximum power production was 100 mW m−2 geometric anode area, highest reported power output for a plant microbial fuel cell. Cathode overpotential was the main potential loss in the period of oxygen reduction due to slow oxygen reduction kinetics at the cathode. Ferricyanide reduction improved the kinetics at the cathode and increased current generation with a maximum of 254%. In the period of ferricyanide reduction, the main potential loss was transport loss. This research shows potential application of microbial fuel cell technology in salt marshes for bio-energy production with the plant microbial fuel cell

Microbial community structure elucidates performance of Glyceria maxima plant microbial fuel cell

The plant microbial fuel cell (PMFC) is a technology in which living plant roots provide electron donor, via rhizodeposition, to a mixed microbial community to generate electricity in a microbial fuel cell. Analysis and localisation of the microbial community is necessary for gaining insight into the competition for electron donor in a PMFC. This paper characterises the anode–rhizosphere bacterial community of a Glyceria maxima (reed mannagrass) PMFC. Electrochemically active bacteria (EAB) were located on the root surfaces, but they were more abundant colonising the graphite granular electrode. Anaerobic cellulolytic bacteria dominated the area where most of the EAB were found, indicating that the current was probably generated via the hydrolysis of cellulose. Due to the presence of oxygen and nitrate, short-chain fatty acid-utilising denitrifiers were the major competitors for the electron donor. Acetate-utilising methanogens played a minor role in the competition for electron donor, probably due to the availability of graphite granules as electron acceptors

A comparison of high‑throughput plasma NMR protocols for comparative untargeted metabolomics (Metabolomics

Following publication of the original article, the authors would like to correct a sentence in the paragraph “1H-NMR spectra were recorded at 298 K…” under the heading “NMR experiments”. The sentence currently reads: “The LED pulse sequence had the form -RD-901-G1- 1801-G1-901-G2-T-901-G1-1801-G1-901-G2-t-901-acquire FID, where RD is a relaxation delay, 901 is a 901 RF pulse, G1 is the pulsed-field gradient that is applied to allow editing, 1801 is a 1801 RF pulse, G2 is a spoil gradient applied to remove unwanted magnetization components. The diffusion delay Δ is the time during which the molecules are allowed to diffuse—this is the period (901-G1-1801-G1- 901-G2-T-); and t is a delay to allow the longitudinal eddy currents caused within the sample to decay (Beckonert et al. 2007).” The sentence should read: “The LED pulse sequence had the form -RD-90°-G1- 180°-G1-90°-G2-T-90°-G1-180°-G1-90°-G2-t-90°-acquire FID, where RD is a relaxation delay, 90° is a 90° RF pulse, G1 is the pulsed-field gradient that is applied to allow editing, 180° is a 180° RF pulse, G2 is a spoil gradient applied to remove unwanted magnetization components. The diffusion delay ? is the time during which the molecules are allowed to diffuse—this is the period (90°-G1-180°-G1-90°-G2 T-); and t is a delay to allow the longitudinal eddy currents caused within the sample to decay (Beckonert et al. 2007).” This has been corrected with this erratum.</p

Controlling Ethanol Use in Chain Elongation by CO₂ Loading Rate

Chain elongation is an open-culture biotechnological process which converts volatile fatty acids (VFAs) into medium chain fatty acids (MCFAs) using ethanol and other reduced substrates. The objective of this study was to investigate the quantitative effect of CO₂ loading rate on ethanol usages in a chain elongation process. We supplied different rates of CO₂ to a continuously stirred anaerobic reactor, fed with ethanol and propionate. Ethanol was used to upgrade ethanol itself into caproate and to upgrade the supplied VFA (propionate) into heptanoate. A high CO₂ loading rate (2.5 L_CO2·L^–1·d^–1) stimulated excessive ethanol oxidation (EEO; up to 29%) which resulted in a high caproate production (10.8 g·L^–1·d^–1). A low CO₂ loading rate (0.5 L_CO2·L^–1·d^–1) reduced EEO (16%) and caproate production (2.9 g·L^–1·d^–1). Heptanoate production by VFA upgrading remained constant (∼1.8 g·L^–1·d^–1) at CO₂ loading rates higher than or equal to 1 L_CO2·L^–1·d^–1. CO₂ was likely essential for growth of chain elongating microorganisms while it also stimulated syntrophic ethanol oxidation. A high CO₂ loading rate must be selected to upgrade ethanol (e.g., from lignocellulosic bioethanol) into MCFAs whereas lower CO₂ loading rates must be selected to upgrade VFAs (e.g., from acidified organic residues) into MCFAs while minimizing use of costly ethanol