Modification of bacterial cell membrane to accelerate decolorization of textile wastewater effluent using microbial fuel cells: role of gamma radiation

The aim of the present work was to increase bacterial adhesion on anode via inducing membrane modifications to enhance textile wastewater treatment in Microbial Fuel Cell (MFC). Real textile wastewater was used in mediator-less MFCs for bacterial enrichment. The enriched bacteria were pre-treated by exposure to 1 KGy gamma radiation and were tested in MFC setup. Bacterial cell membrane permeability and cell membrane charges were measured using noninvasive dielectric spectroscopy measurements. The results show that pre-treatment using gamma radiation resulted in biofilm formation and increased cell permeability and exopolysaccharide production; this was reflected in both MFC performance (average voltage 554.67 mV) and decolorization (96.42%) as compared to 392.77 mV and 60.76% decolorization for non-treated cells. At the end of MFC operation, cytotoxicity test was performed for treated wastewater using a dermal cell line, the results obtained show a decrease in toxicity from 24.8 to 0 (v/v%) when cells were exposed to gamma radiation. Fourier-transform infrared (FTIR) spectroscopy showed an increase in exopolysaccharides in bacterial consortium exposed to increasing doses of gamma radiation suggesting that gamma radiation increased exopolysaccharide production, providing transient media for electron transfer and contributing to accelerating MFC performance. Modification of bacterial membrane prior to MFC operation can be considered highly effective as a pre-treatment tool that accelerates MFC performance

Life cycle assessment of constructed wetland systems for wastewater treatment coupled with microbial fuel cells

The aim of this study was to assess the environmental impact of microbial fuel cells (MFCs) implemented in constructed wetlands (CWs). To this aim a life cycle assessment (LCA) was carried out comparing three scenarios: 1) a conventional CW system (without MFC implementation); 2) a CW system coupled with a gravel-based anode MFC, and 3) a CW system coupled with a graphite-based anode MFC. All systems served a population equivalent of 1500 p.e. They were designed to meet the same effluent quality. Since MFCs implemented in CWs improve treatment efficiency, the CWs coupled with MFCs had lower specific area requirement compared to the conventional CW system. The functional unit was 1 m3 of wastewater. The LCA was performed with the software SimaPro® 8, using the CML-IA baseline method. The three scenarios considered showed similar environmental performance in all the categories considered, with the exception of Abiotic Depletion Potential. In this impact category, the potential environmental impact of the CW system coupled with a gravel-based anode MFC was around 2 times higher than that generated by the conventional CW system and the CW system coupled with a graphite-based anode MFC. It was attributed to the large amount of less environmentally friendly materials (e.g. metals, graphite) for MFCs implementation, especially in the case of gravel-based anode MFCs. Therefore, the CW system coupled with graphite-based anode MFC appeared as the most environmentally friendly solution which can replace conventional CWs reducing system footprint by up to 20%. An economic assessment showed that this system was around 1.5 times more expensive than the conventional CW system.Peer ReviewedPostprint (author's final draft

Consortium Building For PEM MFC Using Synthetic Media As Substrate

Microbial production of electricity is an important form of bioenergy since Microbial Fuel cells (MFC) offer the possibility of extracting electric current from a wide range of organic wastes and renewable biomass. Factors affecting the MFC operational effectiveness are the MFC design and the bacterial metabolism and electron transfer. The purpose of this study is to identify species which are responsible for electricity generation so as to build a suitable consortium and to investigate the relative efficiencies between the microbial consortiums. Enrichment by repeated transfer of a bacterial consortium harvested from the anode compartment of a MFC with synthetic media as a substrate increased the output from an initial level of 34 mA to a maximal level of 363 mA. Scanning electron microscope image indicated the enhanced microbial biofilm deposition over the electrode which were not initially detected in the community

Microbial fuel cells: a green and alternative source for bioenergy production

Microbial fuel cell (MFC) represents one of the green technologies for the production of bioenergy. MFCs using microalgae produce bioenergy by converting solar energy into electrical energy as a function of metabolic and anabolic pathways of the cells. In the MFCs with bacteria, bioenergy is generated as a result of the organic substrate oxidation. MFCs have received high attention from researchers in the last years due to the simplicity of the process, the absence in toxic by-products, and low requirements for the algae growth. Many studies have been conducted on MFC and investigated the factors affecting the MFC performance. In the current chapter, the performance of MFC in producing bioenergy as well as the factors which influence the efficacy of MFCs is discussed. It appears that the main factors affecting MFC’s performance include bacterial and algae species, pH, temperature, salinity, substrate, mechanism of electron transfer in an anodic chamber, electrodes materials, surface area, and electron acceptor in a cathodic chamber. These factors are becoming more influential and might lead to overproduction of bioenergy when they are optimized using response surface methodology (RSM)

Brain-state determines learning improvements after transcranial alternating-current stimulation to frontal cortex

Published in final edited form as: Brain Stimul. 2018 ; 11(4): 723–726. doi:10.1016/j.brs.2018.02.008BACKGROUND Theories of executive control propose that communication between medial frontal cortex (MFC) and lateral prefrontal cortex (lPFC) is critical for learning. 6-Hz phase synchronization may be the mechanism by which neural activity between MFC and lPFC is coordinated into a functional network. Recent evidence suggests that switching from eyes closed to open may induce a change in brain-state reflected by enhanced executive control and related functional connectivity. OBJECTIVE/HYPOTHESIs To examine whether causal manipulation of MFC and lPFC can improve learning according to the brain-state induced by switching from eyes closed to open. METHODS Within-subjects, sham-controlled, double-blind study of 30 healthy subjects, each receiving 6-Hz in-phase high definition transcranial alternating-current stimulation (HD-tACS) applied to MFC and right lPFC prior to performing a time estimation task. RESULTS HD-tACS with eyes open improved learning ability relative to sham, whereas HD-tACS with eyes closed had no significant effect on behavior. CONCLUSION Results suggest a phase-sensitive mechanism in frontal cortex mediates components of learning performance in a state-dependent manner.Accepted manuscrip

Anti fungal activity of alcoholic extract of Peganum harmala seeds

In our study, it was aimed to determine antifungal activity of Peganum harmala on medically important yeasts and molds in vitro. Fungal suspensions of Candida spp and aspergillus spp isolated from the clinical specimens were treated with serial dilutions of P. harmala alcoholic extract in Sabouraud Broth. The titers included: 1/20, 1/40, 1/80, 1/160, 1/320, 1/640, and incubated for 24 h at 30°C. Anti fungal activity of the extract was determined as MIC and MFC. For the determination of MFC, a small volume of above serial dilutions was cultured on SGA 4% medium. After 24 to 72 h of incubation at 30°C, the cultures were looked for fungal growth. The highest and lowest inhibitory effects of P. harmala extract were determined on C. glabrata (MIC: 0.312 mg/ml) and C. albicans (MIC: 1.25 mg/ml), respectively. The MFC for Candida species was differed from 0.62 to 2.5 mg/ml. The highest fungicidal effect was seen on C. glabrata and C. tropicalis (MFC: 0.62 and 0.125 mg/ml, respectively) and the lowest was for C. albicans (MFC: 2.5 mg/ml). The treatment of Aspergillus suspensions with Perganum extract showed a decreasing of growth and sporolation without definite inhibition. The alcoholic extract of P. harmala showed a fungicidal activity on opportunistic yeasts, Candida spp, and a decreasing sporolation for aspergillus most importamt species. © 2011 Academic Journals

Investigation of a SPR based refractive index sensor using a single mode fiber with a large D shaped microfluidic channel

In this work, a highly sensitive surface plasmon resonance (SPR) sensor based on a single mode fiber (SMF) incorporating a large microfluidic channel (MFC) for refractive index (RI) sensing is designed and optimized using a full-vectorial finite element method (FEM). The fluidic channel size can be varied according to the requirement due to the availability of the large cladding diameter of SMF, which makes it simple and easy to fabricate. The proposed novel sensor is favourable to both analytes and metallic strips. The D-shaped hollow section above the core is filled with the measurand analytes and a gold (Au) strip is deposited on the base of the MFC, as it is known as the most attractive metal for SPR. Our numerical simulations illustrate that the confinement loss of the designed sensor is highly influenced by the distance of the MFC from the core along with the width and thickness of the Au strip. The designed sensor shows an average sensitivity of 1350 nm/RIU and maximum sensitivity of 8250 nm/RIU in the sensing range of 1.33-1.35 and 1.41-1.43, respectively. However, for a small variation of na at a step of 0.005, within ranges like 1.415, 1.420, and 1.425, we have achieved a maximum sensitivity of 7000 nm/RIU, 9000 nm/RIU and 11000 nm/RIU, respectively. This novel SPR sensor with MFC can open up a new opportunity in the application of chemical and biological sensing

Assessment of the microbial community in the cathode compartment of a plant microbial fuel cell

Introduction: In plant microbial fuel cells (plant-MFCs) living plants and microorganisms form an electrochemical unit able to produce clean and sustainable electricity from solar energy. It is reasonable to assume that besides the bacteria in the anode compartment also the cathode compartment plays a crucial role for a stable high current producing plant-MFC. In this study we aim to identify dominant bacterial species in the cathode compartment of the plant-MFC

Change in Nutritional Status Modulates the Abundance of Critical Pre-initiation Intermediate Complexes During Translation Initiation \u3cem\u3ein Vivo\u3c/em\u3e

In eukaryotic translation initiation, eIF2∙GTP–Met-tRNAiMet ternary complex (TC) interacts with eIF3–eIF1–eIF5 complex to form the multifactor complex (MFC), while eIF2∙GDP associates with eIF2B for guanine nucleotide exchange. Gcn2p phosphorylates eIF2 to inhibit eIF2B. Here we evaluate the abundance of eIFs and their pre-initiation intermediate complexes in gcn2 deletion mutant grown under different conditions. We show that ribosomes are three times as abundant as eIF1, eIF2 and eIF5, while eIF3 is half as abundant as the latter three and hence, the limiting component in MFC formation. By quantitative immunoprecipitation, we estimate that ∼ 15% of the cellular eIF2 is found in TC during rapid growth in a complex rich medium. Most of the TC is found in MFC, and important, ∼ 40% of the total eIF2 is associated with eIF5 but lacks tRNAiMet. When the gcn2Δ mutant grows less rapidly in a defined complete medium, TC abundance increases threefold without altering the abundance of each individual factor. Interestingly, the TC increase is suppressed by eIF5 overexpression and Gcn2p expression. Thus, eIF2B-catalyzed TC formation appears to be fine-tuned by eIF2 phosphorylation and the novel eIF2/eIF5 complex lacking tRNAiMet