Make the distinction among Warburg and pseudocapacitive responses. Overall, we testedMake the distinction between Warburg

Make the distinction among Warburg and pseudocapacitive responses. Overall, we tested
Make the distinction between Warburg and pseudocapacitive responses. Overall, we tested the hypothesis that the rotating disk electrode can be used as an electrochemical tool that controls mass transfer processes when studying electrochemically active biofilms and facilitates our understanding of EIS in microbially driven electrochemical systems.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptMaterials and MethodsBioelectrochemical Cell Biofilms have been grown within a constantly fed, temperature controlled electrochemical cell as shown in Figure 2. The counter electrode was placed behind porous glass. The functioning electrode, on which G.sulfurreducens respired, was a five mm diameter glassy carbon rotating disk electrode (#970-00060, Gamry Instruments, Warminster, PA). The glassy carbon surface was polished with 0.1 m alumina suspension on a felt pad followed by five min sonication in IL-23 custom synthesis deionized (DI) water. A final polish using 0.05 m alumina suspension was done followed by a further 5 min sonication in DI water. The functioning electrode was mounted towards the cell utilizing a high-precision adapter with ball-bearing (Gamry Instruments #970-00089). The counter electrode was a graphite rod (Sigma-Aldrich #496545), and the reference electrode was a saturated KCl AgAgCl reference. The reactor physique was a temperature-controlled electrochemical cell (Gamry Instruments #990-00249) modified to permit continuous feeding. Norprene tubing (Cole-Parmer #EW-06404-14 and #EW-06404-13) was used for the feed and waste streams, respectively. Flow breakers have been utilized within the feed and waste streams to prevent back contamination. A 0.2-mm filter was used in the gas inlet to sparge a mixture of N2CO2 (80 20 ). Gas inlet stress was adjustedBiotechnol Bioeng. Author manuscript; available in PMC 2014 November 30.Babuta and BeyenalPageslightly above the water column stress inside the cell to provide optimistic pressure devoid of vigorous cIAP-2 Storage & Stability mixing by increasing gas bubbles. Yet another 0.2-m filter was used at the gas outlet to relieve stress buildup. The entire setup except for the reference and working electrodes have been autoclaved for 20 min at 121 . The growth medium was autoclaved separately inside a 1L autoclavable glass bottle for 20 min at 121 . When the biofilm reactor and development medium cooled to area temperature, the development medium bottle was aseptically connected to the biofilm reactor feed stream. Operating and reference electrodes had been placed in 70 vv ethanol in DI water for 45 min beneath UV exposure ahead of getting placed inside the cell. A temperature controller was employed to keep a cell temperature of 30 using the glass jacket. A mixture of N2CO2 (80 20 ) gas was then sparged for 24 h. Development Medium Development medium applied to develop G.sulfurreducens strain PCA (ATCC 51573) biofilms consisted of: potassium chloride, 0.38 gL; ammonium chloride, 0.2 gL; sodium phosphate monobasic, 0.069 gL; calcium chloride, 0.04 gL; magnesium sulfate heptahydrate, 0.2 gL; sodium carbonate, 2 gL; Wolfe’s vitamin answer, 10 mLL; modified Wolfe’s mineral solution, 10 mLL. Acetate (20 mM) was provided because the electron donor. No fumarate or other soluble electron acceptor was added for the development medium. Expanding the Biofilms The cell was then inoculated with G.sulfurreducens inoculum prepared following a previously published approach (Babauta et al., 2012). Cell volume was 115 mL. Within 24 h, the existing began to raise as well as the feed pump was turned on. The dilution rate from the cell was 0.01 h-1 (or possibly a.