{"id":{"repo_id":"umn","oai_identifier":"oai:conservancy.umn.edu:11299/277315"},"canonical_url":"https://search.dev.ndltd.org/etd/umn/oai:conservancy.umn.edu:11299/277315","repository":{"repo_id":"umn","name":"University of Minnesota","base_url":"https://conservancy.umn.edu/server/oai/request"},"display":{"title":"Biodegradation of QACs in lake and river water and effects on the microbial community","abstract":"Quaternary ammonium compounds (QACs) are a class of commonly used organic cationic biocides. Disinfectant products contain QACs that are above the minimum inhibitory concentration of most microbes. After usage and wastewater treatment, however, many QACs end up in surface waters at sub-inhibitory concentrations. Exposure to sub-inhibitory QAC concentrations can facilitate the evolution of resistance to QACs and may also lead to co-resistance to other antimicrobial agents. Few studies have investigated the impact of repeated exposure of sub-inhibitory concentrations of QACs in lake and river water to microbial communities in terms of function (biodegradation of QACs) and the presence of antibiotic resistance genes (ARGs). In this study, the impact of repeated exposure to different classes of QACs on the microbial communities in a heavily impacted river water (Mississippi River) and a pristine lake (Trout Lake) were investigated. It was observed that both of the classes of QACs studied, benzalkyldimethyl ammonium compounds (BACs) and dialkyldimethyl ammonium compounds (DADMACs), were completely degraded in both Trout Lake and Mississippi River over a period of days. The degradation rates of each QAC varied but were always faster in Mississippi River water and generally increased with repeated amendment. Quantitative polymerase chain reaction (qPCR) results showed a higher abundance of several ARGs (qacF, mexB, and sul1) in Mississippi River water than in Trout Lake samples. ARGs also tended to increase in abundance with repeated QAC amendments and with higher concentration amendments. Overall, this study highlights how repeated exposure to sub-inhibitory QAC concentrations can alter microbial response and help build resistance towards QACs.","abstract_html":"Quaternary ammonium compounds (QACs) are a class of commonly used organic cationic biocides. Disinfectant products contain QACs that are above the minimum inhibitory concentration of most microbes. After usage and wastewater treatment, however, many QACs end up in surface waters at sub-inhibitory concentrations. Exposure to sub-inhibitory QAC concentrations can facilitate the evolution of resistance to QACs and may also lead to co-resistance to other antimicrobial agents. Few studies have investigated the impact of repeated exposure of sub-inhibitory concentrations of QACs in lake and river water to microbial communities in terms of function (biodegradation of QACs) and the presence of antibiotic resistance genes (ARGs). In this study, the impact of repeated exposure to different classes of QACs on the microbial communities in a heavily impacted river water (Mississippi River) and a pristine lake (Trout Lake) were investigated. It was observed that both of the classes of QACs studied, benzalkyldimethyl ammonium compounds (BACs) and dialkyldimethyl ammonium compounds (DADMACs), were completely degraded in both Trout Lake and Mississippi River over a period of days. The degradation rates of each QAC varied but were always faster in Mississippi River water and generally increased with repeated amendment. Quantitative polymerase chain reaction (qPCR) results showed a higher abundance of several ARGs (qacF, mexB, and sul1) in Mississippi River water than in Trout Lake samples. ARGs also tended to increase in abundance with repeated QAC amendments and with higher concentration amendments. Overall, this study highlights how repeated exposure to sub-inhibitory QAC concentrations can alter microbial response and help build resistance towards QACs.","abstract_has_math":false,"creators":["Joseph, Frantz"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-07","date_published":"2025-07","updated_at":"2026-07-24T05:20:00Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/11299/277315","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Joseph, Frantz"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-12-12T11:26:13Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2025-12-12T11:26:13Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-07"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/11299/277315"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["University of Minnesota M.S. thesis. July 2025. Major: Civil Engineering. Advisors: William Arnold, Paige Novak. 1 computer file (PDF); vii, 70 pages."]},{"key":"dc:description.abstract","label":"Abstract","values":["Quaternary ammonium compounds (QACs) are a class of commonly used organic cationic biocides. Disinfectant products contain QACs that are above the minimum inhibitory concentration of most microbes. After usage and wastewater treatment, however, many QACs end up in surface waters at sub-inhibitory concentrations. Exposure to sub-inhibitory QAC concentrations can facilitate the evolution of resistance to QACs and may also lead to co-resistance to other antimicrobial agents. Few studies have investigated the impact of repeated exposure of sub-inhibitory concentrations of QACs in lake and river water to microbial communities in terms of function (biodegradation of QACs) and the presence of antibiotic resistance genes (ARGs). In this study, the impact of repeated exposure to different classes of QACs on the microbial communities in a heavily impacted river water (Mississippi River) and a pristine lake (Trout Lake) were investigated. It was observed that both of the classes of QACs studied, benzalkyldimethyl ammonium compounds (BACs) and dialkyldimethyl ammonium compounds (DADMACs), were completely degraded in both Trout Lake and Mississippi River over a period of days. The degradation rates of each QAC varied but were always faster in Mississippi River water and generally increased with repeated amendment. Quantitative polymerase chain reaction (qPCR) results showed a higher abundance of several ARGs (qacF, mexB, and sul1) in Mississippi River water than in Trout Lake samples. ARGs also tended to increase in abundance with repeated QAC amendments and with higher concentration amendments. Overall, this study highlights how repeated exposure to sub-inhibitory QAC concentrations can alter microbial response and help build resistance towards QACs."]},{"key":"dc:title","label":"Title","values":["Biodegradation of QACs in lake and river water and effects on the microbial community"]}]}],"canonical_facts":{"dc:creator":["Joseph, Frantz"],"dc:date.accessioned":["2025-12-12T11:26:13Z"],"dc:date.available":["2025-12-12T11:26:13Z"],"dc:date.issued":["2025-07"],"dc:description":["University of Minnesota M.S. thesis. July 2025. Major: Civil Engineering. Advisors: William Arnold, Paige Novak. 1 computer file (PDF); vii, 70 pages."],"dc:description.abstract":["Quaternary ammonium compounds (QACs) are a class of commonly used organic cationic biocides. Disinfectant products contain QACs that are above the minimum inhibitory concentration of most microbes. After usage and wastewater treatment, however, many QACs end up in surface waters at sub-inhibitory concentrations. Exposure to sub-inhibitory QAC concentrations can facilitate the evolution of resistance to QACs and may also lead to co-resistance to other antimicrobial agents. Few studies have investigated the impact of repeated exposure of sub-inhibitory concentrations of QACs in lake and river water to microbial communities in terms of function (biodegradation of QACs) and the presence of antibiotic resistance genes (ARGs). In this study, the impact of repeated exposure to different classes of QACs on the microbial communities in a heavily impacted river water (Mississippi River) and a pristine lake (Trout Lake) were investigated. It was observed that both of the classes of QACs studied, benzalkyldimethyl ammonium compounds (BACs) and dialkyldimethyl ammonium compounds (DADMACs), were completely degraded in both Trout Lake and Mississippi River over a period of days. The degradation rates of each QAC varied but were always faster in Mississippi River water and generally increased with repeated amendment. Quantitative polymerase chain reaction (qPCR) results showed a higher abundance of several ARGs (qacF, mexB, and sul1) in Mississippi River water than in Trout Lake samples. ARGs also tended to increase in abundance with repeated QAC amendments and with higher concentration amendments. Overall, this study highlights how repeated exposure to sub-inhibitory QAC concentrations can alter microbial response and help build resistance towards QACs."],"dc:identifier.uri":["https://hdl.handle.net/11299/277315"],"dc:language.iso":["en"],"dc:title":["Biodegradation of QACs in lake and river water and effects on the microbial community"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:20:00Z"}