Generation of Electricity by Electrogenic Bacteria in a Microbial Fuel Cell Powered by Waste Water

The present study aimed at isolation characterization and evaluation of electrogenic bacteria for electricity generation using waste water. In this context, waste water samples were collected from University of Nizwa waste water treatment plant. A total of eight distinct bacterial isolates were isolated from these samples by serial dilution and plating on LB Agar medium. The bacterial isolates were than grown at different temperatures and pH. DNA from bacterial samples was isolated and 16S rRNA gene amplification was carried out. The 16S rRNA gene PCR products were directly sequenced and the resulting sequence was blasted using BLASTn. Based on BLAST results, the bacterial strains were identified. The bacteria were used in different combinations to generate electricity from waste water in microbial fuel cells constructed using plastic bottles. The microbial isolates were found to produce varying levels of currents and their electrogenic potential in waste water was observed to increase with the passage of time.

Electrogenic sulfur oxidation mediated by cable bacteria and its ecological effects

At the sediment-water interfaces,filamentous cable bacteria transport electrons from sulfide oxidation along their filaments towards oxygen or nitrate as electron acceptors.These multicellular bacteria belonging to the family Desulfobulbaceae thus form a biogeobattery that mediates redox processes between multiple elements.Cable bacteria were first reported in 2012.In the past years,cable bacteria have been found to be widely distributed across the globe.Their potential in shaping the surface water environments has been extensively studied but is not fully elucidated.In this review,the biogeochemical characteristics,conduction mechanisms,and geographical distribution of cable bacteria,as well as their ecological effects,are systematically reviewed and discussed.Novel insights for understanding and applying the role of cable bacteria in aquatic ecology are summarized.

In-Cell Nanoelectronics:Opening the Door to Intracellular Electrophysiology

Establishing a reliable electrophysiological recording platform is crucial for cardiology and neuroscience research.Noninvasive and label-free planar multitransistors and multielectrode arrays are conducive to perform the large-scale cellular electrical activity recordings,but the signal attenua-tion limits these extracellular devices to record subthreshold activities.In recent decade,in-cell nanoelectronics have been rapidly developed to open the door to intracellular electrophysi-ology.With the unique three-dimensional nanotopography and advanced penetration strategies,high-throughput and high-fidelity action potential like signal recordings is expected to be realized.This review summarizes in-cell nanoelectronics from versatile nano-biointerfaces,penetration strategies,active/pas-sive nanodevices,systematically analyses the applications in electrogenic cells and especially evaluates the influence of nanodevices on the high-quality intracellular electrophysiological signals.Further,the opportunities,challenges and broad prospects of in-cell nanoelectronics are prospected,expecting to promote the development of in-cell electrophysiological platforms to meet the demand of theoretical investigation and clinical application.

Hepatocyte growth factor gene therapy prevents radiation-induced liver damage

AIM: To transfer human HGF gene into the liver of rats by direct electroporation as a means to prevent radiationinduced liver damage.METHODS: Rat whole liver irradiation model was accomplished by intra-operative approach. HGF plasmid was injected into liver and transferred by electroporation using a pulse generator. Control rats (n = 8) received electrogene therapy (EGT) vehicle plasmid and another 8rats received HGF-EGT 100 μg 48 h before WLIR.Expression of HGF in liver was examined by RT-PCR and ELISA methods. Apoptosis was determined by TUNEL assay. Histopathology was evaluated 10 wk after whole liver irradiation.RESULTS: Marked decrease of apoptotic cells and downregulation of transforming growth factor-beta 1 (TGF-β1)mRNA were observed in the HGF-EGT group 2 d after liver irradiation compared to control animals. Less evidence of radiation-induced liver damage was observed morphologically in liver specimen 10 wk after liver irradiation and longer median survival time was observed from HGF-EGT group (14 wk) compared to control rats (5 wk). (P = 0.031).CONCLUSION: For the first time it has been demonstrated that HGF-EGT would prevent liver from radiation-induced liver damage by preventing apoptosis and down-regulation of TGF-β1.

Simultaneous electrogenerative leaching of chalcopyrite concentrate and MnO_2

In order to enhance the electrogenerative leaching rate of chalcopyrite concentrate reasonably, the principle of generative process was applied to simultaneous leaching of chalcopyrite concentrate and MnO2. The results show that Cu^2＋ and Mn^2＋ in addition to electrical energy could be acquired in the simultaneous electrogenerative leaching process. The leaching cell has the open circuit potential of about 1.0 V and gains quantity of electricity of about 700 C. The optimum leaching rates of Cu^2＋ and Mn^2＋ are 23.10% and 22.1%, respectively after electrogenera- tive leaching for about 10 h under the present conditions.

Electrogenerative leaching of nickel sulfide concentrate with ferric chloride

In order to utilize the chemical energy in hydrometallurgical process of sulfide minerals reasonably and to simplify the purifying process, the electrogenerative process was applied and a dual cell system was introduced to investigate FeCl3 leaching of nickel sulfide concentrate. Some factors influencing the electrogenerative leaching, such as electrode structure, temperature and solution concentration were studied. The results show that a certain quantity of electrical energy accompanied with the leached products can be acquired in the electrogenerative leaching process. The output current and power increase with the addition of acetylene black to the electrode. Varying the components of electrode just affects the polarization degree of anode. Increasing FeCl3 concentration results in a sharp increase in the output of the leaching cell when c（FeCl3） is less than 0.1 mol/L. The optimum value of NaCl concentration for electrogenerative leaching nickel sulfide concentrate with FeCl3 is 3.0 mol/L. Temperature influences electrogenerative leaching by affecting anodic and cathodic polarization simultaneously. The apparent activation energy is determined to be 34.63 kJ/mol in the range of 298 K to 322 K. The leaching rate of Ni2+ is 29.3% after FeCl3 electrogenerative leaching of nickel sulfide concentrate for 620 min with a filter bag electrode.

Mechanism of influence of chloride ions on electrogenerative leaching of sulfide minerals

A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl^- concentration. The influence on the electrogenerative leaching rate decreases when the Cl^- concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl^- is relatively low, the electrogenerative leaching rates are predicted to have 2/5,3/7,1/3 and 1/3 order dependence on Cl^- concentration for chalcopyrite concentrate,nickel concentrate, sphalerite and galena. As concentration of Cl^- increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl^- becomes weak.

Electrogenerative leaching for sphalerite-MnO_2 in the presence of Acidithiobacillus thiooxidans

A dual cell system was used to study the electrogenerative leaching sphalerite-MnO2 in the presence and absence of Acidithiobacillus thiooxidans (A. thiooxidans). The polarization of anode and cathode, and the relationship between the electric quantity (Q) and some factors, such as the dissolved rate of Zn2+ and Fe2+, and the time in the bio-electro-generating simultaneous leaching (BEGL) and electro-generating simultaneous leaching (EGL) were studied. A three-electrode system was applied to studying anodic and cathodic self-corrosion current, which was inappreciable compared with the galvanic current between sphalerite and MnO2. The results show that the dissolved Zn2+ in the presence of A. thiooxidans is nearly 43% higher than that in the absence of A. thiooxidans; the electrogenerative quantity in the former is about 150% more than that in the latter. The accumulated sulfur on the surface of sulfides produced in the electrogenerative leaching process can be oxidized in the presence of A. thiooxidans, and the ratio of biologic electric quantity reaches 27.9% in 72 h.

Microbial Reduction of Graphene Oxide by Shewanella

Graphene oxide （GO） can be reduced to graphene in a normal aerobic setup under ambient conditions as mediated by microbial respiration of Shewanella cells. The microbially-reduced graphene （MRG） exhibited excellent electrochemical properties. Extracellular electron transfer pathways at the cell/GO interface were systematically investigated, suggesting both direct electron transfer and electron mediators are involved in the GO reduction.

Factors Affecting the Performance of Single-Chamber Soil Microbial Fuel Cells for Power Generation

There is limited information about the factors that affect the power generation of single-chamber microbial fuel cells （MFCs） using soil organic matter as a fuel source. We examined the effect of soil and water depths, and temperature on the performance of soil MFCs with anode being embedded in the flooded soil and cathode in the overlaying water. Results showed that the MFC with 5 cm deep soil and 3 cm overlaying water exhibited the highest open circuit voltage of 562 mV and a power density of 0.72 mW m-2. The ohmic resistance increased with more soil and water. The polarization resistance of cathode increased with more soil while that of anode increased with more water. During the 30 d operation, the cell voltage positively correlated with temperature and reached a maximum of 162 mV with a 500 ft external load. After the operation, the bacterial 16S rRNA gene from the soil and anode was sequenced. The bacteria in the soil were more diverse than those adhere to the anode where the bacteria were mainly affiliated to Eseherichia coli and Deltaproteobacteria. In summary, the two bacterial groups may generate electricity and the electrical properties were affected by temperature and the depth of soil and water.