Matching Items (34)

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Genomes of Geoalkalibacter ferrihydriticus Z-0531T and Geoalkalibacter subterraneus Red1T, Two Haloalkaliphilic Metal-Reducing Deltaproteobacteria

Description

We sequenced and annotated genomes of two haloalkaliphilic Deltaproteobacteria, Geoalkalibacter ferrihydriticus Z-0531[superscript T] (DSM 17813) and Geoalkalibacter subterraneus Red1[superscript T] (DSM 23483). During assembly, we discovered that the DSMZ stock

We sequenced and annotated genomes of two haloalkaliphilic Deltaproteobacteria, Geoalkalibacter ferrihydriticus Z-0531[superscript T] (DSM 17813) and Geoalkalibacter subterraneus Red1[superscript T] (DSM 23483). During assembly, we discovered that the DSMZ stock culture of G. subterraneus was contaminated. We reisolated G. subterraneus in axenic culture and redeposited it in DSMZ and JCM.

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  • 2015-03-12

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Draft Genome Sequence of the Gram-Positive Thermophilic Iron Reducer Thermincola ferriacetica Strain Z-0001T

Description

A 3.19-Mbp draft genome of the Gram-positive thermophilic iron-reducing Firmicutes isolate from the Peptococcaceae family, Thermincola ferriacetica Z-0001, was assembled at ~100× coverage from 100-bp paired-end Illumina reads. The draft

A 3.19-Mbp draft genome of the Gram-positive thermophilic iron-reducing Firmicutes isolate from the Peptococcaceae family, Thermincola ferriacetica Z-0001, was assembled at ~100× coverage from 100-bp paired-end Illumina reads. The draft genome contains 3,274 predicted genes (3,187 protein coding genes) and putative multiheme c-type cytochromes.

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  • 2015-09-24

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Generation of High Current Densities by Pure Cultures of Anode-Respiring Geoalkalibacter spp. under Alkaline and Saline Conditions in Microbial Electrochemical Cells

Description

Anode-respiring bacteria (ARB) generate electric current in microbial electrochemical cells (MXCs) by channeling electrons from the oxidation of organic substrates to an electrode. Production of high current densities by monocultures

Anode-respiring bacteria (ARB) generate electric current in microbial electrochemical cells (MXCs) by channeling electrons from the oxidation of organic substrates to an electrode. Production of high current densities by monocultures in MXCs has resulted almost exclusively from the activity of Geobacter sulfurreducens, a neutrophilic freshwater Fe(III)-reducing bacterium and the highest-current-producing member documented for the Geobacteraceae family of the Deltaproteobacteria. Here we report high current densities generated by haloalkaliphilic Geoalkalibacter spp., thus broadening the capability for high anode respiration rates by including other genera within the Geobacteraceae. In this study, acetate-fed pure cultures of two related Geoalkalibacter spp. produced current densities of 5.0 to 8.3 and 2.4 to 3.3 A m[superscript −2] under alkaline (pH 9.3) and saline (1.7% NaCl) conditions, respectively. Chronoamperometric studies of halophilic Glk. subterraneus DSM 23483 and alkaliphilic Glk. ferrihydriticus DSM 17813 suggested that cells performed long-range electron transfer through electrode-attached biofilms and not through soluble electron shuttles. Glk. ferrihydriticus also oxidized ethanol directly to produce current, with maximum current densities of 5.7 to 7.1 A m[superscript −2] and coulombic efficiencies of 84 to 95%. Cyclic voltammetry (CV) elicited a sigmoidal response with characteristic onset, midpoint, and saturation potentials, while CV performed in the absence of an electron donor suggested the involvement of redox molecules in the biofilm that were limited by diffusion. These results matched those previously reported for actively respiring Gb. sulfurreducens biofilms producing similar current densities (~5 to 9 A m[superscript −2]).

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  • 2013-04-30

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Augmenting Protocols for In-situ Separation of Biocompounds.

Description

In our modern world the source of for many chemicals is to acquire and refine oil. This process is becoming an expensive to the environment and to human health. Alternative

In our modern world the source of for many chemicals is to acquire and refine oil. This process is becoming an expensive to the environment and to human health. Alternative processes for acquiring the final product have been developed but still need work. One product that is valuable is butanol. The normal process for butanol production is very intensive but there is a method to produce butanol from bacteria. This process is better because it is more environmentally safe than using oil. One problem however is that when the bacteria produce too much butanol it reaches the toxicity limit and stops the production of butanol. In order to keep butanol from reaching the toxicity limit an adsorbent is used to remove the butanol without harming the bacteria. The adsorbent is a mesoporous carbon powder that allows the butanol to be adsorbed on it. This thesis explores different designs for a magnetic separation process to extract the carbon powder from the culture.

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  • 2015-05

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Biochemical Methane Potential (BMP) Tests and Microbial Electrochemical Cells (MECs) Identify Differences in Pretreated Waste Activates Sludge (WAS) Streams

Description

Anaerobic digestion (AD), a common process in wastewater treatment plants, is traditionally assessed with Biochemical Methane Potential (BMP) tests. Hydrolysis is considered its rate-limiting step. During my research, I assessed

Anaerobic digestion (AD), a common process in wastewater treatment plants, is traditionally assessed with Biochemical Methane Potential (BMP) tests. Hydrolysis is considered its rate-limiting step. During my research, I assessed the impact of pretreatment on BMPs and microbial electrochemical cells (MECs). In the first set of experiments, BMP tests were performed using alkaline and thermal pretreated waste activated sludge (WAS), a control group, and a negative control group as samples and AD sludge (ADS) as inoculum. The data obtained suggested that BMPs do not necessarily require ADS, since samples without inoculum produced 5-20% more CH4. However, ADS appears to reduce the initial methanogenesis lag in BMPs, as no pH inhibition and immediate CH4 production were observed. Consumption rate constants, which are related to hydrolysis, were calculated using three methods based on CH4 production, SSCOD concentration, and the sum of both, called the lumped parameter. All the values observed were within literature values, yet each provide a different picture of what is happening in the system. For the second set of experiments, the current production of 3 H-type MECs were compared to the CH4 production of BMPs to assess WAS solids' biodegradability and consumption rates relative to the pretreatment methods employed for their substrate. BMPs fed with pretreated and control WAS solids were performed at 0.42 and 1.42 WAS-to-ADS ratios. An initial CH4 production lag of about 12 days was observed in the BMP assays, but MECs immediately began producing current. When compared in terms of COD, MECs produced more current than the BMPs produced CH4, indicating that the MEC may be capable of consuming different types of substrate and potentially overestimating CH4 production in anaerobic digesters. I also observed 2 to 3 different consumption events in MECs versus 3 for BMP assays, but these had similar magnitudes, durations, and starting times in the control and thermal pretreated WAS-fed assays and not in alkaline assays. This might indicate that MECs identified the differences of alkaline pretreatment, but not between control WAS and thermal pretreated WAS. Furthermore, HPLC results suggest at least one hydrolysis event, as valerate, butyrate, and traces of acetate are observed in the reactors' effluents. Moreover, a possible inhibition of valerate-fixing microbial communities due to pretreatment and the impossibility of valerate consumption by ARB might explain its presence in the reactors' effluents.

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  • 2017-05

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Effects of Organic Carbon Source and Light Exposure on Glycogen Mitigation in Synechocystis sp. PCC 6803 Mutant Lacking PSII for Microbial Electro-Photosynthesis

Description

Biofuels are a carbon-neutral energy source proving to be a sustainable alternative to greenhouse gas-emitting fossil fuels that are accelerating the detrimental effects of anthropogenic climate change. A developing system

Biofuels are a carbon-neutral energy source proving to be a sustainable alternative to greenhouse gas-emitting fossil fuels that are accelerating the detrimental effects of anthropogenic climate change. A developing system aimed at more efficiently producing biofuels is called Microbial Electro-Photosynthesis (MEPS). In MEPS, a Synechocystis sp. PCC 6803 mutant lacking photosystem II (PSII) receives electrons by a hydroduroquinone (DQH2) mediator from a more efficient water-splitting electrochemical cell, rather than splitting water itself using PSII. However, growth of the Synechocystis cells prior to use in MEPS requires an organic carbon source, leading to internally-stored electron sources, namely glycogen, that compete with preferred DQH2 mediator-delivered electrons. In this study, the effects of organic carbon source (pyruvate, acetate, glucose, and no carbon source) and light condition (light or dark) on the physiology and P700+ reduction kinetics of photoheterotrophically grown Synechocystis mutants were studied with the hope of identifying a maintenance culturing method that allowed for both cell viability and mitigated glycogen storage. While no significant decreases in internal electron-sources were found with these methods, it was observed that Synechocystis cells fed pyruvate in the light had most successfully reduced competition between internal electron sources and preferred DQH2-delivered electrons. This study suggests that these experiments be re-run after removing exogenous carbon sources and that the nutrients available to the cells and their effects on pyruvate and acetate uptake be further investigated.

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Date Created
  • 2020-12

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Electrochemical Characterization of a High-Current-Density Microbial Biocathode with an Air Diffusion Membrane

Description

In microbial fuel cells (MFCs) the biocathode is developed as a potential alternative to chemical cathodic catalysts, which are deemed as expensive and unsustainable for applications. These cells utilize different

In microbial fuel cells (MFCs) the biocathode is developed as a potential alternative to chemical cathodic catalysts, which are deemed as expensive and unsustainable for applications. These cells utilize different types of microorganisms as catalysts to promote biodegradation of organic matter while simultaneously converting energy released in metabolic reactions into electrical energy. Most current research have focused more on the anodic microbes, including the current generating bacteria species, anodic microbial community composition, and the mechanisms of the extracellular electron transfer. Compared to the anode, research on the microbes of the biocathode of the MFCs are very limited and are heavily focused on the role of the bacteria in the system. Thus, further understand of the mechanism of the microbial community in the biocathode will create new engineering applications for sustainable energy. Previous research conducted by Strycharz-Glaven et al. presented an electrochemical analysis of a Marinobacter-dominated biocathode communitygrown on biocathodes in sediment/seawater-based MFCs. Chronoamperometry results indicated that current densities up to -0.04 A/m2 were produced for the biocathode. Cyclic voltammetry responses indicated a midpoint potential at 0.196 V ± 0.01 V. However, the reactor design for these experiments showed that no oxygen is supplied to the electrochemical system. By incorporating an air diffusion membrane to the cathode of the reactor, chronoamperometry results have produced current density in the system up to -0.15 A/m2. Cyclic voltammetry results have also displayed a midpoint potential of 0.25 V ± 0.01 V under scan rates of 0.2 mV/s. Thus, this electrochemical setup has increased the current output of the system.

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Date Created
  • 2016-05

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Characterizing Buffers to Maximize Peroxide Production in the Cathode Chamber of Microbial Fuel Cells

Description

Microbial fuel cells (MFCs) facilitate the conversion of organic matter to electrical current to make the total energy in black water treatment neutral or positive and produce hydrogen peroxide to

Microbial fuel cells (MFCs) facilitate the conversion of organic matter to electrical current to make the total energy in black water treatment neutral or positive and produce hydrogen peroxide to assist the reuse of gray water. This research focuses on wastewater treatment at the U.S. military forward operating bases (FOBs). FOBs experience significant challenges with their wastewater treatment due to their isolation and dangers in transporting waste water and fresh water to and from the bases. Even though it is theoretically favorable to produce power in a MFC while treating black water, producing H2O2 is more useful and practical because it is a powerful cleaning agent that can reduce odor, disinfect, and aid in the treatment of gray water. Various acid forms of buffers were tested in the anode and cathode chamber to determine if the pH would lower in the cathode chamber while maintaining H2O2 efficiency, as well as to determine ion diffusion from the anode to the cathode via the membrane. For the catholyte experiments, phosphate and bicarbonate were tested as buffers while sodium chloride was the control. These experiments determined that the two buffers did not lower the pH. It was seen that the phosphate buffer reduced the H2O2 efficiency significantly while still staying at a high pH, while the bicarbonate buffer had the same efficiency as the NaCl control. For the anolyte experiments, it was shown that there was no diffusion of the buffers or MFC media across the membrane that would cause a decrease in the H2O2 production efficiency.

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  • 2016-05

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Continuous Hydrogen Peroxide Production using Microbial Electrochemical Cells

Description

Alternative ion exchange membranes for implementation in a peroxide production microbial electrochemical cel (PP-MEC) are explored through membrane stability tests with NaCl electrolyte and stabilizer EDTA at varying operational pHs.

Alternative ion exchange membranes for implementation in a peroxide production microbial electrochemical cel (PP-MEC) are explored through membrane stability tests with NaCl electrolyte and stabilizer EDTA at varying operational pHs. PP-MEC performance parameters \u2014 H2O2 concentration, current density, coulombic efficiency and power input required \u2014 are optimized over a 7 month continuous operation period based on their response to changes in HRT, EDTA concentration, air flow rate and electrolyte. I found that EDTA was compatible for use with the membranes. I also determined that AMI membranes were preferable to CMI and FAA because it was consistently stable and maintained its structural integrity. Still, I suggest testing more membranes because the AMI degraded in continuous operation. The PP-MEC produced up to 0.38 wt% H2O2, enough to perform water treatment through the Fenton process and significantly greater than the 0.13 wt% batch PP-MEC tests by previous researchers. It ran at > 0.20 W-hr/g H2O2 power input, ~ three orders of magnitude less than what is required for the anthraquinone process. I recommend high HRT and EDTA concentration while running the PP- MEC to increase H2O2 concentration, but low HRT and low EDTA concentration to decrease power input required. I recommend NaCl electrolyte but suggest testing new electrolytes that may control pH without degrading H2O2. I determined that air flow rate has no effect on PP-MEC operation. These recommendations should optimize PP-MEC operation based on its application.

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Date Created
  • 2016-05

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An Examination of the Impact of Support Design on 316 Stainless Steel Supports

Description

The removal of support material from metal 3D printed objects is a laborious necessity for the post-processing of powder bed fusion printing (PBF). Supports are typically mechanically removed by machining

The removal of support material from metal 3D printed objects is a laborious necessity for the post-processing of powder bed fusion printing (PBF). Supports are typically mechanically removed by machining techniques. Sacrificial supports are necessary in PBF printing to relieve thermal stresses and support overhanging parts often resulting in the inclusion of supports in regions of the part that are not easily accessed by mechanical removal methods. Recent innovations in PBF support removal include dissolvable metal supports through an electrochemical etching process. Dissolvable PBF supports have the potential to significantly reduce the costs and time associated with traditional support removal. However, the speed and effectiveness of this approach is inhibited by numerous factors such as support geometry and metal powder entrapment within supports. To fully realize this innovative approach, it is necessary to model and understand the design parameters necessary to optimize support structures applicable to an electrochemical etching process. The objective of this study was to evaluate the impact of block additive manufacturing support parameters on key process outcomes of the dissolution of 316 stainless steel support structures. The parameters investigated included hatch spacing and perforation, and the outcomes of interests included time required for completion, surface roughness, and effectiveness of the etching process. Electrical current was also evaluated as an indicator of process completion. Analysis of the electrical current throughout the etching process showed that the dissolution is diffusion limited to varying degrees, and is dependent on support structure parameters. Activation and passivation behavior was observed during current leveling, and appeared to be more pronounced in non-perforated samples with less dense hatch spacing. The correlation between electrical current and completion of the etching process was unclear, as the support structures became mechanically removable well before the current leveled. The etching process was shown to improve surface finish on unsupported surfaces, but support was shown to negatively impact surface finish. Tighter hatch spacing was shown to correlate to larger variation in surface finish, due to ridges left behind by the support structures. In future studies, it is recommended current be more closely correlated to process completion and more roughness data be collected to identify a trend between hatch spacing and surface roughness.

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Date Created
  • 2018-05