DOCSLIB.ORG

Hamid's Dissertation

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Hamid's Dissertation BIOCONVERSION OF CELLULOSE INTO ELECTRICAL ENERGY IN MICROBIAL FUEL CELLS DISSERTATION Presented in Partial Fulfillment of the Requirements for The Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Hamid Rismani-Yazdi, M.S. * * * * * The Ohio State University 2008 Dissertation Committee: Approved by Dr. Ann D. Christy, Advisor Dr. Burk A. Dehority Dr. Olli H. Tuovinen Dr. Alfred B. Soboyejo Advisor Food, Agricultural and Biological Dr. Zhongtang Yu Engineering Graduate Program ABSTRACT In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. ii The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57.5, 53 and 47 mWm-2, respectively. The anode potential varied under the different circuit loads employed. Higher coulombic efficiencies were achieved in MFCs with lower external resistance. The effect of different external resistances on the bacterial diversity and metabolism in cellulose-fed MFCs was investigated as the fourth objective. DGGE analysis of partial 16S rRNA genes showed clear differences between the planktonic and the anode-attached populations at various external resistances. Cellulose degradation was complete (< 0.1% residual), and there were no discernible differences among the MFCs. HPLC analysis of short chain fatty acids (SCFA) revealed that anaerobic degradation of cellulose was accompanied by production of acetic, propionic, butyric, isobutyric, valeric, isovaleric, and lactic acids, with acetic acid being predominant. The profile of metabolites was different among the MFCs. The concentrations of SCFA were higher in MFCs with larger external resistance. High levels of SCFA indicated that fermentative metabolism dominated over anaerobic respiration, resulting in relatively low coulombic efficiencies. The accumulation of SCFA at higher circuit resistances corresponded to lower power outputs. iii Methanogenesis shifts the flow of electrons available from the substrate away from electricity generation in MFCs. The fifth objective of this research was to assess the influence of methane formation on the performance of cellulose-fed MFCs under long- term operation. Two-compartment MFCs were inoculated with a ruminal microbial consortium and fed colloidal cellulose (0.5 g l-1 d-1) as the sole substrate. Replicate MFCs were operated under two different external resistances of 20 and 100 ohms, designated as R20Ω and R100Ω. During the first week of operation 0.31 ± 0.004 (± SD) and 0.44 ± 0.004 mmol of methane was produced in R20Ω and R100Ω MFCs, respectively. Methanogenesis was suppressed, however, to below the detection limit (< 0.5 ×10-3 mmol) after 90 days of operation. The decrease in methane production was accompanied with an increase in the performance of MFCs. The current output of the MFCs increased from 0.1 mA during the first week to 3.3 and 2.2 mA on day 90, resulting in 29 and 25% coulombic efficiency for the R20Ω and R100Ω MFCs, respectively. A maximum volumetric power density of 3.5 -3 W m was achieved in R20Ω MFCs, which was three times greater than that obtained with -3 R100Ω MFCs (1.03 W m ). The diversity of methanogens in cellulose-fed MFCs was also characterized. It was shown that the suppression of methanogenesis was accompanied by a decrease in the diversity of methanogens and changes in the concentration of SCFA, as revealed by DGGE analysis of PCR-amplified 16S rRNA genes and HPLC analysis, respectively. Analysis of partial 16S rRNA gene Sequences indicated that the most predominant methanogens were related to the family Methanobacteriaceae. The results demonstrate that electricity can be generated from cellulose by exploiting rumen microorganisms as biocatalysts. Results suggest that oxidation of iv metabolites with the anode as an electron sink was a rate limiting step in the conversion of cellulose to electricity in MFCs. This study also demonstrates that the size of external resistance significantly affects the bacterial diversity and characteristic output of MFCs. Thus the external resistance may be a useful tool to control microbial communities and consequently enhance performance of MFCs. Furthermore, this study shows that methanogenesis competes with electricity generation at the early stages of MFC operation but operating conditions suppress methanogenic activity over time. An improved understanding of the microbial communities, interspecies interactions and processes involved in electricity generation is essential to effectively design and control cellulose-fed MFCs for enhanced performance. In addition, technical and biological optimization is needed to maximize power output of these systems. v Dedicated to my family vi ACKNOWLEDGMENTS I would like to express my gratitude and deep appreciation to Dr. Ann D. Christy, advisor of my dissertation research, for her infinite support, encouragement, and patience as well as the magnificent mentorship she provided me with throughout the time it took me to complete this research and write the dissertation. It was a tremendous honor working with her. The members of my dissertation committee, Dr. Olli Tuovinen, Dr. Zhongtang Yu, Dr. Burk Dehority and Dr. Alfred Soboyejo, have generously given their time and expertise to improve my work. I thank them for their contribution and their good-natured support. Specifically, I wish to extend my sincere thanks and appreciation to Dr. Olli Tuovinen whose knowledge, wisdom, and advice have supported me over the course of my academic training at the Ohio State University. His technical and editorial guidance have been an inspiration to me and a critical key to the completion of my dissertation. He was always available, even during his sabbatical leave, to work on my writings and discuss new topics, ideas, and results. I am grateful to Dr. Zhongtang Yu for his valuable insights and ideas as well as countless advice that supported and expanded my work. His wide expertise in the field of molecular biology has played as essential role in this research project. I would like to sincerely thank Dr. Burk Dehority who triggered my vii academic journey in the US, and provided me with an incredible technical training and innumerable guidance before and throughout my dissertation research. I am also thankful to Dr. Alfred Soboyejo, for his continued encouragement and inspiring advice that supported and enlightened my research. I am grateful too for the support and advice from my faculty colleagues in Department of Food, Agricultural and Biological Engineering. I would like to thank many persons who helped me with my experiments, especially Chris Gecik for helping with electrical instrumentation, Carl Cooper and Kevin Duemmel for their assistance with fabrication of MFCs, and Don Irvine for providing computer support. Carol Moody, Kay Elliot, and Kevin Davison are also thanked for their administrative support. I must acknowledge as well the many friends, colleagues and students who assisted, advised, and supported my research and writing efforts over the years. Especially, I need to express my gratitude and deep appreciation to Sarah Carver, Mike Nelson, James Douglass, Kerry Hughes Zwierschke, Eun Kyoung Kim, Jill Stephen, Nikki Skrinak, Bethany Frew Corcoran, Brian Henslee, Peter Gehres, and Clayton Bettin. The Iranian Students and Scholars at the Ohio State University and their families made these years in Ohio, away from home, very special, very lively and very enriching. The enjoyable times spent with friends provided a well-needed balance to the work; thank you for your support and friendship. I am deeply indebted to my family for their care, support and encouragement. I am grateful to my parents without whom I would never have been able to achieve so much. I am also thankful to my mother and father in-law for their support, and encouragement. My brothers Saied and Ehsan, I am thankful for having you in my life. I viii have been blessed with an absolutely superb grandfather and honor the memory of the three of my grandparents whom I have lost, peace be upon their souls. Last and most importantly, I would like to thank the love of my life, my wife Najmeh, for her unyielding devotion and love, endless support, patience, and encouragement and all the helps she provided me with during the course of completing this research and writing the dissertation.
Load more

Recommended publications
  • Clostridium Butyricum Strains and Dysbiosis Linked to Necrotizing
    Clostridium butyricum Strains and Dysbiosis Linked to Necrotizing Enterocolitis in Preterm Neonates Nadim Cassir, Samia Benamar, Jacques Bou Khalil, Olivier Croce, Marie Saint-Faust, Aurélien Jacquot, Matthieu Million, Said Azza, Nicholas Armstrong, Mireille Henry, et al. To cite this version: Nadim Cassir, Samia Benamar, Jacques Bou Khalil, Olivier Croce, Marie Saint-Faust, et al.. Clostrid- ium butyricum Strains and Dysbiosis Linked to Necrotizing Enterocolitis in Preterm Neonates. Clinical Infectious Diseases, Oxford University Press (OUP), 2015, 61 (7), pp.1107–1115. hal-01985792 HAL Id: hal-01985792 https://hal.archives-ouvertes.fr/hal-01985792 Submitted on 18 Jan 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Clostridium butyricum Strains and Dysbiosis Linked to Necrotizing Enterocolitis in Preterm Neonates Nadim Cassir,1 Samia Benamar,1 Jacques Bou Khalil,1 Olivier Croce,1 Marie Saint-Faust,2 Aurélien Jacquot,3 Matthieu Million, 1 Said Azza,1 Nicholas Armstrong,1 Mireille Henry,1 Priscilla Jardot,1 Catherine Robert,1 Catherine Gire,4
    [Show full text]
  • Probiotics and the Prevention of Clostridioides Difficile: a Viewre of Existing Systematic Reviews
    Minnesota State University, Mankato Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato All Theses, Dissertations, and Other Capstone Theses, Dissertations, and Other Capstone Projects Projects 2020 Probiotics and the Prevention of Clostridioides difficile: A viewRe of Existing Systematic Reviews Andrea L. Onstad Minnesota State University, Mankato Follow this and additional works at: https://cornerstone.lib.mnsu.edu/etds Part of the Bacteria Commons, Bacterial Infections and Mycoses Commons, Digestive System Diseases Commons, and the Family Practice Nursing Commons Recommended Citation Onstad, A. L. (2020). Probiotics and the prevention of Clostridioides difficile: Ae r view of existing systematic reviews [Master’s alternative plan paper, Minnesota State University, Mankato]. Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. This APP is brought to you for free and open access by the Theses, Dissertations, and Other Capstone Projects at Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. It has been accepted for inclusion in All Theses, Dissertations, and Other Capstone Projects by an authorized administrator of Cornerstone: A Collection of Scholarly and Creative Works for Minnesota State University, Mankato. 1 Probiotics and the Prevention of Clostridioides difficile: A Review of Existing Systematic Reviews Andrea L. Onstad School of Nursing, Minnesota State University, Mankato NURS 695: Alternate Plan Paper Dr. Rhonda Cornell May 1, 2020 2 Abstract Clostridioides difficile is the leading cause of infectious diarrhea (Vernaya et al., 2017). Probiotics have been proposed to provide a protective benefit against Clostridioides difficile infection (CDI). The objective of this literature review was to examine the research evidence pertaining to the use of probiotics for the prevention of CDI in individuals receiving antibiotic therapy.
    [Show full text]
  • ENERGY MANAGEMENT of MICROBIAL FUEL CELLS for HIGH EFFICIENCY WASTEWATER TREATMENT and ELECTRICITY GENERATION by FERNANDA LEITE
    ENERGY MANAGEMENT OF MICROBIAL FUEL CELLS FOR HIGH EFFICIENCY WASTEWATER TREATMENT AND ELECTRICITY GENERATION by FERNANDA LEITE LOBO B.S., Universidade do Estado do Amazonas, 2012 B.S., Universidade Federal do Amazonas, 2013 M.S., University of Colorado Boulder, 2017 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree of Doctor of Philosophy Department of Civil, Environmental, and Architectural Engineering 2018 This thesis entitled: Energy Management of Microbial Fuel Cells for High Efficiency Wastewater Treatment and Electricity Generation written by Fernanda Leite Lobo has been approved for the Department of Civil, Environmental, and Architectural Engineering Jae-Do Park, Ph.D. JoAnn Silverstein, Ph.D. Mark Hernandez, Ph.D. Rita Klees, Ph.D. Zhiyong (Jason) Ren, Ph.D. Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. ii Leite Lobo, Fernanda (Ph.D., Environmental Engineering) Energy Management of Microbial Fuel Cells for High Efficiency Wastewater Treatment and Electricity Generation Thesis directed by Associate Professor Zhiyong Jason Ren Abstract In order to develop communities in a sustainable manner it is necessary to think about how to provide basic and affordable services including sanitation and electricity. Wastewater has energy embedded in the form biodegradable organic matter, but most of the conventional systems use external energy to treat the wastewater instead of harvest its energy. Microbial fuel cells (MFCs) are unique systems that are capable of converting chemical energy of biodegradable substrates embedded in the waste materials into renewable electricity.
    [Show full text]
  • Microbial Structure and Energy Generation in Microbial Fuel Cells Powered with Waste Anaerobic Digestate
    energies Article Microbial Structure and Energy Generation in Microbial Fuel Cells Powered with Waste Anaerobic Digestate Dawid Nosek * and Agnieszka Cydzik-Kwiatkowska Department of Environmental Biotechnology, University of Warmia and Mazury in Olsztyn, Słoneczna 45 G, 10-709 Olsztyn, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-89-523-4144; Fax: +48-89-523-4131 Received: 19 July 2020; Accepted: 7 September 2020; Published: 10 September 2020 Abstract: Development of economical and environment-friendly Microbial Fuel Cells (MFCs) technology should be associated with waste management. However, current knowledge regarding microbiological bases of electricity production from complex waste substrates is insufficient. In the following study, microbial composition and electricity generation were investigated in MFCs powered with waste volatile fatty acids (VFAs) from anaerobic digestion of primary sludge. Two anode sizes were tested, resulting in organic loading rates (OLRs) of 69.12 and 36.21 mg chemical oxygen demand (COD)/(g MLSS d) in MFC1 and MFC2, respectively. Time of MFC operation affected the microbial · structure and the use of waste VFAs promoted microbial diversity. High abundance of Deftia sp. and Methanobacterium sp. characterized start-up period in MFCs. During stable operation, higher OLR in MFC1 favored growth of exoelectrogens from Rhodopseudomonas sp. (13.2%) resulting in a higher and more stable electricity production in comparison with MFC2. At a lower OLR in MFC2, the percentage of exoelectrogens in biomass decreased, while the abundance of genera Leucobacter, Frigoribacterium and Phenylobacterium increased. In turn, this efficiently decomposed complex organic substances, favoring high and stable COD removal (over 85%).
    [Show full text]
  • Enrichment of Electrochemically Active Bacteria Using Microbial Fuel Cell and Potentiostat
    Enrichment of electrochemically active bacteria using microbial fuel cell and potentiostat Tim Niklas Enke ETH Zurich [email protected] – [email protected] Microbial Diversity 2015 Introduction Microbial fuel cells (MFC) can be applied to harness the power released by metabolically active bacteria as electrical energy (Figure 1). In addition to the energy generation capabilities of MFC, they have been used to generate hydrogen gas and to clean, desalinate or detoxify wastewater [1,2]. Among the bacteria found to be electrochemically active are Geobacter sulfurreducens, Shewanella putrefaciens and Aeromonas hydrophila [2,3,4]. Figure 1: Scheme of a microbial fuel cell. A MFC consists of an anaerobic anode chamber with rich organic matter, such as sludge from wastewater treatment plants or sediment. The anode (1) serves as an electron acceptor in an electron acceptor limited environment and is wired externally (2) over a resistor (3) to a cathode (5). Electrons travel over the circuit and create a current, while protons can pass the proton exchange membrane (4) to reach the oxic cathode chamber. At the cathode, the protons, electrons and oxygen react to form water. In the cathode chamber, a catalyst can facilitate the reaction and thus the movement of electrons. Figure from [https://illumin.usc.edu/assets/media/175/MFCfig2p1.jpg , 08/18/2015]. Even more remarkably, in the deep sea, microbes can power measurement devices that deploy an anode in the anoxic sediments and position a cathode in the oxygen richer water column above, thus exploiting the MFC principle [5]. In a different application, MFC can be used to enrich for bacteria that are capable of extracellular electron transfer (EET) and form a biofilm on the electrode.
    [Show full text]
  • Enhanced Performance of Microbial Fuel Cells by Using Mno2/Halloysite Nanotubes to Modify Carbon Cloth Anodes
    Enhanced performance of microbial fuel cells by using MnO2/Halloysite nanotubes to modify carbon cloth anodes Item Type Article Authors Chen, Yingwen; Chen, Liuliu; Li, Peiwen; Xu, Yuan; Fan, Mengjie; Zhu, Shemin; Shen, Shubao Citation Enhanced performance of microbial fuel cells by using MnO2/ Halloysite nanotubes to modify carbon cloth anodes 2016, 109:620 Energy DOI 10.1016/j.energy.2016.05.041 Publisher PERGAMON-ELSEVIER SCIENCE LTD Journal Energy Rights © 2016 Elsevier Ltd. All rights reserved. Download date 29/09/2021 22:45:04 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final accepted manuscript Link to Item http://hdl.handle.net/10150/621214 Enhanced Performance of Microbial Fuel Cells by Using MnO2/Halloysite Nanotubes to modify carbon cloth anodes Yingwen Chen1,*,†, Liuliu Chen1,†, Peiwen Li2, Yuan Xu1, Mengjie Fan1, Shemin Zhu3, 1 Shubao Shen 1College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 210009, China 2Department of Aerospace and Mechanical Engineering, the University of Arizona, Tucson, AZ 85721, USA 3College of Material Science and Engineering, Nanjing Tech University, Nanjing 210009, China † The authors contributed equally to this work. *Corresponding author at: College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No.30 Puzhu south Road, Nanjing, 210009, PR China TEL: (+86 25) 58139922 FAX: (+86 25) 58139922 E-mail address: [email protected] (Yingwen Chen) ABSTRACT: The modification of anode materials is important to enhance the power generation of microbial fuel cells (MFCs). A novel and cost-effective modified anode that is fabricated by dispersing manganese dioxide (MnO2) and Halloysite nanotubes (HNTs) on carbon cloth to improve the MFCs’ power production was reported.
    [Show full text]
  • Microfluidic Microbial Fuel Cells for Microstructure Interrogations By
    Microfluidic Microbial Fuel Cells for Microstructure Interrogations by Erika Andrea Parra A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Engineering - Mechanical Engineering in the Graduate Division of the University of California, Berkeley Committee in charge: Professor Liwei Lin, Chair Professor Carlos Fendandez-Pello Professor John D. Coates Fall 2010 Microfluidic Microbial Fuel Cells for Microstructure Interrogations Copyright 2010 by Erika Andrea Parra 1 Abstract Microfluidic Microbial Fuel Cells for Microstructure Interrogations by Erika Andrea Parra Doctor of Philosophy in Engineering - Mechanical Engineering University of California, Berkeley Professor Liwei Lin, Chair The breakdown of organic substances to retrieve energy is a naturally occurring process in nature. Catabolic microorganisms contain enzymes capable of accelerating the disintegration of simple sugars and alcohols to produce separated charge in the form of electrons and protons as byproducts that can be harvested extracellularly through an electrochemical cell to produce electrical energy directly. Bioelectrochemical energy is then an appealing green alternative to other power sources. However, a number of fundamental questions must be addressed if the technology is to become economically feasible. Power densities are low, hence the electron flow through the system: bacteria-electrode connectivity, the volumetric limit of catalyst loading, and the rate-limiting step in the system must be understood and optimized. This project investigated the miniaturization of microbial fuel cells to explore the scaling of the biocatalysis and generate a platform to study fundamental microstructure effects. Ultra- micro-electrodes for single cell studies were developed within a microfluidic configuration to quantify these issues and provide insight on the output capacity of microbial fuel cells as well as commercial feasibility as power sources for electronic devices.
    [Show full text]
  • Computational Simulation of Mass Transport and Energy Transfer in the Microbial Fuel Cell System
    University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 12-2015 Computational Simulation of Mass Transport and Energy Transfer in the Microbial Fuel Cell System Shiqi Ou University of Tennessee - Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Catalysis and Reaction Engineering Commons, Energy Systems Commons, Numerical Analysis and Computation Commons, and the Transport Phenomena Commons Recommended Citation Ou, Shiqi, "Computational Simulation of Mass Transport and Energy Transfer in the Microbial Fuel Cell System. " PhD diss., University of Tennessee, 2015. https://trace.tennessee.edu/utk_graddiss/3598 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Shiqi Ou entitled "Computational Simulation of Mass Transport and Energy Transfer in the Microbial Fuel Cell System." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Doctor of Philosophy, with a major in Mechanical Engineering. Matthew M. Mench, Major Professor We have read this dissertation and recommend its acceptance: Kivanc Ekici, Feng-Yuan Zhang, Vasilios Alexiades Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Computational Simulation of Mass Transport and Energy Transfer in the Microbial Fuel Cell System A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Shiqi Ou December 2015 ii Copyright © 2015 by Shiqi Ou All rights reserved.
    [Show full text]
  • Optimization of the Electrolyte Parameters and Components in Zinc Particle Fuel Cells
    energies Article Optimization of the Electrolyte Parameters and Components in Zinc Particle Fuel Cells Thangavel Sangeetha 1,2,† , Po-Tuan Chen 3,† , Wu-Fu Cheng 4, Wei-Mon Yan 1,2,* and K. David Huang 4,* 1 Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan; [email protected] 2 Research Center of Energy Conservation for New Generation of Residential, Commercial, and Industrial Sectors, National Taipei University of Technology, Taipei 10608, Taiwan 3 Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan; [email protected] 4 Department of Vehicle Engineering, National Taipei University of Technology, Taipei 10608, Taiwan; [email protected] * Correspondence: [email protected] (W.-M.Y.); [email protected] (K.D.H.); Tel.: +886-2-2771-2171 (ext. 3676) (K.D.H.) † These authors contributed equally to this work (TS and PTC). Received: 18 February 2019; Accepted: 19 March 2019; Published: 21 March 2019 Abstract: Zinc (Zn)-air fuel cells (ZAFC) are a widely-acknowledged type of metal air fuel cells, but optimization of several operational parameters and components will facilitate enhanced power performance. This research study has been focused on the investigation of ZAFC Zn particle fuel with flowing potassium hydroxide (KOH) electrolyte. Parameters like optimum electrolyte concentration, temperature, and flow velocity were optimized. Moreover, ZAFC components like anode current collector and cathode conductor material were varied and the appropriate materials were designated. Power performance was analyzed in terms of open circuit voltage (OCV), power, and current density production and were used to justify the results of the study.
    [Show full text]
  • Germinants and Their Receptors in Clostridia
    JB Accepted Manuscript Posted Online 18 July 2016 J. Bacteriol. doi:10.1128/JB.00405-16 Copyright © 2016, American Society for Microbiology. All Rights Reserved. 1 Germinants and their receptors in clostridia 2 Disha Bhattacharjee*, Kathleen N. McAllister* and Joseph A. Sorg1 3 4 Downloaded from 5 Department of Biology, Texas A&M University, College Station, TX 77843 6 7 Running Title: Germination in Clostridia http://jb.asm.org/ 8 9 *These authors contributed equally to this work 10 1Corresponding Author on September 12, 2018 by guest 11 ph: 979-845-6299 12 email: [email protected] 13 14 Abstract 15 Many anaerobic, spore-forming clostridial species are pathogenic and some are industrially 16 useful. Though many are strict anaerobes, the bacteria persist in aerobic and growth-limiting 17 conditions as multilayered, metabolically dormant spores. For many pathogens, the spore-form is Downloaded from 18 what most commonly transmits the organism between hosts. After the spores are introduced into 19 the host, certain proteins (germinant receptors) recognize specific signals (germinants), inducing 20 spores to germinate and subsequently outgrow into metabolically active cells. Upon germination 21 of the spore into the metabolically-active vegetative form, the resulting bacteria can colonize the 22 host and cause disease due to the secretion of toxins from the cell. Spores are resistant to many http://jb.asm.org/ 23 environmental stressors, which make them challenging to remove from clinical environments. 24 Identifying the conditions and the mechanisms of germination in toxin-producing species could 25 help develop affordable remedies for some infections by inhibiting germination of the spore on September 12, 2018 by guest 26 form.
    [Show full text]
  • Characterization of an Endolysin Targeting Clostridioides Difficile
    International Journal of Molecular Sciences Article Characterization of an Endolysin Targeting Clostridioides difficile That Affects Spore Outgrowth Shakhinur Islam Mondal 1,2 , Arzuba Akter 3, Lorraine A. Draper 1,4 , R. Paul Ross 1 and Colin Hill 1,4,* 1 APC Microbiome Ireland, University College Cork, T12 YT20 Cork, Ireland; [email protected] (S.I.M.); [email protected] (L.A.D.); [email protected] (R.P.R.) 2 Genetic Engineering and Biotechnology Department, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh 3 Biochemistry and Molecular Biology Department, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh; [email protected] 4 School of Microbiology, University College Cork, T12 K8AF Cork, Ireland * Correspondence: [email protected] Abstract: Clostridioides difficile is a spore-forming enteric pathogen causing life-threatening diarrhoea and colitis. Microbial disruption caused by antibiotics has been linked with susceptibility to, and transmission and relapse of, C. difficile infection. Therefore, there is an urgent need for novel therapeutics that are effective in preventing C. difficile growth, spore germination, and outgrowth. In recent years bacteriophage-derived endolysins and their derivatives show promise as a novel class of antibacterial agents. In this study, we recombinantly expressed and characterized a cell wall hydrolase (CWH) lysin from C. difficile phage, phiMMP01. The full-length CWH displayed lytic activity against selected C. difficile strains. However, removing the N-terminal cell wall binding domain, creating CWH351—656, resulted in increased and/or an expanded lytic spectrum of activity. C. difficile specificity was retained versus commensal clostridia and other bacterial species.
    [Show full text]
  • Microbial Fuel Cells for Improved Bioremediation
    Microbial Fuel Cells for Improved Bioremediation Emi Lemberg1, Joe Vallino2 1University of Chicago 5801 S Ellis Ave, Chicago IL 60637 USA 2The Ecosystems Center: Semester in Environmental Science Marine Biological Laboratory Woods Hole, Massachusetts 02543 USA 2017 Fall Semester 1 Abstract Microbial fuel cells (MFCs) can be used as a power source and as a tool for bioremediation. By creating an electrical connection between the anaerobic sediments and aerobic water column, a MFC can increase the metabolism rates of bacteria in the sediment, allowing the bacteria to break down complex molecules they would not be able to consume otherwise. This experiment focuses on the breakdown of organic matter in sediments from Little Pond in Falmouth, Massachusetts. While the sediments already contain high concentrations of organic matter, caffeine was amended to the sediments to as a proxy for difficult to degrade pollutants. This experiment examines the effect of an added 2 V potential has on of organic matter decomposition in a sediment MFC (Driven MFC). During the incubation, a pH gradient developed in the Driven MFC, with a change in pH of 1.12 on the final day of incubation. The pH gradient caused the current of the MFCs to drop from approximately 2.5 mA to approximately 0.05 mA halfway through the experiment. Additionally, the high pH at the surface of the MFC resulted in the uptake of carbon dioxide for the first 17 days of the incubation. Organic carbon extracted from the sediments suggests that a decrease in the carbon content of sediments occurred; however, the short-term nature of the incubations prevented a statistically significant conclusion when compared to the controls.
    [Show full text]