{"663939":{"#nid":"663939","#data":{"type":"event","title":"PhD Defense by Yael Toporek","body":[{"value":"\u003Cp\u003EIn partial fulfillment of the requirements for the degree of\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDoctor of Philosophy in Biology\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIn the\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EYael Toporek\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EWill defend her dissertation\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003EMolecular mechanisms of microbial pathways\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003Efor environmental contaminant remediation\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EJanuary 9\u003Csup\u003Eth\u003C\/sup\u003E, 2023\u003C\/p\u003E\r\n\r\n\u003Cp\u003E3:00 pm\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Ca href=\u0022https:\/\/gatech.zoom.us\/j\/96188765357?pwd=V0Y1cjhWM0JPc0J4MjEwQzZLRmp3dz09\u0022\u003Ehttps:\/\/gatech.zoom.us\/j\/96188765357?pwd=V0Y1cjhWM0JPc0J4MjEwQzZLRmp3dz09\u003C\/a\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003Cstrong\u003EThesis Advisor:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThomas DiChristina, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee Members:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EBrian Hammer, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Biological Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EFrank Stewart, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDepartment of Microbiology and Cell Biology\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMontana State University\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EAmit Reddi, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Chemistry and Biochemistry\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EMartial Taillefert, Ph.D.\u003C\/p\u003E\r\n\r\n\u003Cp\u003ESchool of Earth and Atmospheric Sciences\u003C\/p\u003E\r\n\r\n\u003Cp\u003EGeorgia Institute of Technology\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EThis thesis examines the molecular mechanism of alternate strategies for remediation of contaminated environments. Radioiodine, perfluoroalkyl substances (PFAS), and 1,4-dioxane represent emerging contaminants of national concern. For example, microbially-catalyzed reductive methylation of\u0026nbsp;\u003Csup\u003E129\u003C\/sup\u003EIO\u003Csub\u003E3\u003C\/sub\u003E\u003Csup\u003E-\u003C\/sup\u003E\u0026nbsp;has received recent attention as an alternate strategy for remediation of radioiodine-contaminated environments. This thesis identified enzymes required for IO\u003Csub\u003E3\u003C\/sub\u003E\u003Csup\u003E-\u0026nbsp;\u003C\/sup\u003Ereduction coupled to organic acid oxidation in the facultative anaerobe\u0026nbsp;\u003Cem\u003EShewanella oneidensis\u003C\/em\u003E: cytoplasmic electron donors are oxidized, and the electrons are transferred through the periplasm via cytochromes of the metal-reducing pathway to extracellular dimethylsulfoxide (DMSO) reductase, which directly reduces IO\u003Csub\u003E3\u003C\/sub\u003E\u003Csup\u003E-\u0026nbsp;\u003C\/sup\u003Eto iodide (I\u003Csup\u003E-\u003C\/sup\u003E) as an alternate substrate. Future work aims to investigate the apparent import of I\u003Csup\u003E-\u0026nbsp;\u003C\/sup\u003Eback to the cytoplasm, where it is putatively methylated and volatilized by a promiscuous thiopurine methyltransferase, presenting a potential strategy for bioremediation of radioiodine. \u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIn the case of PFAS, the industrial surfactant and flame retardant perfluorooctanoic acid (PFOA) has been designated as an emerging contaminant. In the present study, the microbially driven Fenton reaction (MFR) was employed to attempt degradation of PFOA by cycling between aerobic and anaerobic ferric iron (Fe(III))-reducing conditions. Under aerobic conditions,\u003Cem\u003E\u0026nbsp;S. oneidensis\u0026nbsp;\u003C\/em\u003Ereduced molecular oxygen (O\u003Csub\u003E2\u003C\/sub\u003E) to hydrogen peroxide (H\u003Csub\u003E2\u003C\/sub\u003EO\u003Csub\u003E2\u003C\/sub\u003E), while under anaerobic conditions,\u0026nbsp;\u003Cem\u003ES. oneidensis\u003C\/em\u003E\u0026nbsp;reduced Fe(III) to Fe(II). During aerobic-to-anaerobic transition periods, Fe(II) and H\u003Csub\u003E2\u003C\/sub\u003EO\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;interacted chemically via the Fenton reaction to produce contaminant-degrading hydroxyl (HO\u003Csup\u003E\u0026bull;\u003C\/sup\u003E) radicals, which in turn interacted with PFOA. PFOA concentrations, however, remained unchanged, which most likely reflects the stability of carbon-fluorine bonds and consequent inability of HO\u003Csup\u003E\u0026bull;\u003C\/sup\u003E\u0026nbsp;radicals to oxidatively degrade PFOA.\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EFinally, the present study aimed to describe the contribution of\u0026nbsp;several genes related to oxidative stress response in\u0026nbsp;\u003Cem\u003ES. oneidensis\u003C\/em\u003E\u0026nbsp;during aerobic respiration and H\u003Csub\u003E2\u003C\/sub\u003EO\u003Csub\u003E2\u003C\/sub\u003E stress. In contrast to \u003Cem\u003ES. oneidensis\u003C\/em\u003E anaerobic respiration, aerobic respiration is understudied, and a key contributor to the success of MFR in degrading organic and chlorinated environmental contaminants like 1,4-dioxane.\u0026nbsp;This work describes the contribution of individual genes, particularly catalases and peroxidases, to intracellular H\u003Csub\u003E2\u003C\/sub\u003EO\u003Csub\u003E2\u003C\/sub\u003E\u0026nbsp;scavenging rates using the genetically-encoded ratiometric fluorescent sensor HyPer-3 as a reporter.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":"","field_summary_sentence":[{"value":"Molecular mechanisms of microbial pathways for environmental contaminant remediation"}],"uid":"27707","created_gmt":"2022-12-16 15:26:42","changed_gmt":"2022-12-16 15:26:42","author":"Tatianna Richardson","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2023-01-09T15:00:00-05:00","event_time_end":"2023-01-09T17:00:00-05:00","event_time_end_last":"2023-01-09T17:00:00-05:00","gmt_time_start":"2023-01-09 20:00:00","gmt_time_end":"2023-01-09 22:00:00","gmt_time_end_last":"2023-01-09 22:00:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"221981","name":"Graduate Studies"}],"categories":[],"keywords":[{"id":"100811","name":"Phd Defense"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"1788","name":"Other\/Miscellaneous"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[],"email":[],"slides":[],"orientation":[],"userdata":""}}}