Electrical Stress-directed Evolution of Biocatalysts Community Sampled from A Sodic-saline Soil for Microbial Fuel Cells

Abstract

Anode-respiring bacteria (ARB) perform an unusual form of respiration in which their electron acceptor is a solid anode. The focus of this study was to characterize the electrical stress direct evolution of biocatalysts as a way of enriching the community with ARB for microbial fuel cell. The original microbial consortium was sampled from a sodic-saline bottom soil (Texcoco Lake). Interestingly, iron (III) reducing bacteria consortium in the sodic-saline bottom soil was 8500 ± 15 MPN/100 mL by the most probable number method, since microbial reduction of iron (III) is reported to be associated to anode-respiring capabilities. Cyclic voltammetry studies of electrochemical stressed biofilm-ARB were conducted at 28th and 135th days, and an irreversible electron transfer reaction was found possibly related to electron transfer reaction of the cytochrome. The electrochemical impedance spectroscopy results revealed that the resistance of the biofilm-ARB decreased with time (28th day-11.11 ω and 135th day- 5.5 ω ), possibly associated to the adaptability of electroactive biofilm on the graphite electrode surface. Confocal microscopy showed that the biofilms are active in nature and the biofilm-ARB attained ~40 μ m thickness at the 136th day. Electrical stressed-ARB gave a maximum power density of 79.4mW/m2, and unstressed-ARB gave a maximum power density of 41.0mW/m2 in a single-chamber microbial fuel cell (SCMFC). All these electrochemical experiments and evaluation suggest that the electrical-stress directed evolution of ARB community was associated to a more efficient extracellular electron transfer process in SCMFC.

Electricity generation from Nopal biogas effluent using a surface modified clay cup (cantarito) microbial fuel cell

“…In conclusion, the oxidation of the substrate (NBE) by microbes was observed to be more effective/active at closed-circuit rather than at intermittent electrochemical characterization. This can be explained because the higher oxidation of NBE by the microbes is expected with a high ratio of oxidized electron carriers of the culture under the electrochemical stress over the microbes to remove the COD at a higher rate (Sathish-Kumar et al., 2012). Control experiment of NBE revealed 54 % of COD removal at the same period of C-MFC operation.…”

Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

“…The culture was thermally isolated to preserve the medium at +4ºC. The electrochemical enrichment was performed through 11 an electrolysis process using graphite as a working and counter electrodes, applying a potential of -150 mV over 150 days [31][32][33]. The procedure was repeated twice at which point hybrid H inocula was finally obtained.…”

“…Details of the design and construction of a single chamber microbial fuel cell (SCMFC) can be found elsewhere [33]. In summary, the MFC consisted of a vertical cylinder built in glass, 9 cm long and 5.6 cm internal diameter (200 mL capacity).…”

Anodic concentration loss and impedance characteristics in rotating disk electrode microbial fuel cells

“…7 a Nyquist plots from the EIS experiments with an amplitude of 10 mV and a frequency of 10-10,000 kHz. b, c Resistance and capacitance by fitting the impedance results to EEC R 1 (R 2 C 1 )(R 3 C 2 ), where R 1 is the ohmic resistance, R 2 is the anodic resistance, R 3 is the cathodic resistance, C 1 is the anodic capacitance, and C 2 is the cathodic capacitance In microbial fuel cells, bacterial capacitance is an effective compensation to eliminate power overshoot [36]. A characteristic amount of backup capability per unit of power production is normally observed in a MFC.…”