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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Influence Of Nutrients And The Native On E. Coli Survival In The Beach Environment, Brigid Meyers
Influence Of Nutrients And The Native On E. Coli Survival In The Beach Environment, Brigid Meyers
Theses and Dissertations
E. coli is used as an indicator for water quality to determine if water poses a health risk for pathogens. Past research has shown that E. coli is present in high numbers in freshwater beach sands distinct from fecal pollution events, yet the precise mechanism for their persistence in not well understood. Persistent E. coli populations in sand can resuspend into adjacent water and lead to increased beach closures when no threat is present. This work identifies factors that influence the survival of E. coli in sand using laboratory microcosms to replicate beach conditions. Microcosms were deployed to examine the …
A Mechanistic Investigation Of Cytochrome C Nitrite Reductase Catalyzed Reduction Of Nitrite To Ammonia: The Search For Catalytic Intermediates, Shahid Shahid
Theses and Dissertations
Cytochrome c Nitrite Reductase (ccNiR) is a periplasmic homodimeric decaheme enzyme that catalyzes the reduction of nitrite to ammonium in a process that involves six electrons and eight protons. Under standard assay conditions, which use a strong reducing agent as an electron source, catalysis takes place rapidly without producing detectable intermediates. However, intermediates do accumulate when weaker reducing agents are employed, allowing the ccNiR mechanism to be studied. Herein, the early stages of Shewanella oneidensis ccNiR-catalyzed nitrite reduction were investigated in isolation by using the weak reducing agents N,N,N’,N’-tetramethyl-p-phenylenediamine (TMPD) and the 2-electron reduced form of indigo trisulfonate. Experiments were …
Development Of Indicators For Human Fecal Pollution Using Deep-Sequencing Of Microbial Communities, Shuchen Feng
Development Of Indicators For Human Fecal Pollution Using Deep-Sequencing Of Microbial Communities, Shuchen Feng
Theses and Dissertations
The gut microbiome is shaped by both host physiology and environmental factors, which results in unique communities that contain certain members specific to a host. Microbial source tracking (MST) methods that rely on host-specific fecal microorganisms have been applied to detect human fecal pollution over the past two decades. The most common approach uses quantitative polymerase chain reaction (qPCR) to amplify certain sequences of these microorganisms, or human fecal markers. To date, most bacterial human fecal markers have focused on the HF183 cluster within the genus Bacteroides. However, cross-reactions with animals or variable Bacteroides abundance in humans have been found. …
Towards Autonomous Microcystin Detection: Investigating Methods For Automation, Maureen Anne Schneider
Towards Autonomous Microcystin Detection: Investigating Methods For Automation, Maureen Anne Schneider
Theses and Dissertations
Due to increased anthropogenic activity, severe eutrophication is occurring in bodies of water around the world. Effects include decreased water quality, decreased value of surrounding land and recreational use (estimated loss in revenue of 0.67 and 3.96 U.S. billion dollars per year), and increased occurrence of toxin producing Harmful Algal Blooms (HABs). Microcystins are cyclic peptides made up of 7 amino acids and 800-1100 Daltons in size. They are one of the most predominantly produced of these toxins, and therefore was the focus of this study. Numerous structural variants of microcystin (referred to as congeners) exist, but microcystin-LR is one …
Point Of Use Biosand Filters Of The Rural Dominican Republic, Kurtis Quamme
Point Of Use Biosand Filters Of The Rural Dominican Republic, Kurtis Quamme
Theses and Dissertations
The point of use biosand filter (BSF) is used globally as a drinking water treatment solution. In this research, point of use BSFs were inoculated with active biosand from the Linnwood Drinking Water Treatment plant slow sand filter beds (Milwaukee, Wisconsin) and with sands collected from point of use filters operating in the Dominican Republic. These filters were maintained with varying source waters (surface water, groundwater, or tap water to simulate chlorination encountered in the field). The microbial community of filters with varied influents and biosand inoculum were analyzed quantitatively by sequencing and qPCR. Filter efficacy and microbial community were …
The Selective Survival Of Escherichia Coli In Freshwater Beach Sand, Natalie Ann Rumball
The Selective Survival Of Escherichia Coli In Freshwater Beach Sand, Natalie Ann Rumball
Theses and Dissertations
The quantification of Escherichia coli or E. coli is the most common method used to detect recent fecal pollution in recreational water, as this species is known for its high abundance in fecal matter and assumed host-associated nature. However, it has been determined that some strains are capable of long-term survival and potential propagation in non-host environments, such as the beach sand. These long-term environmental survivors are host-independent and are not associated with the same health risks as those E. coli from recent fecal pollution. However, they have been shown to impact how water quality is perceived as they are …
The Mixing Of A River Into Coastal Waters At Two Beaches: Environmental Factors, E. Coli Contributions And Applications For Predictive Models, Adrian Jordan Koski
The Mixing Of A River Into Coastal Waters At Two Beaches: Environmental Factors, E. Coli Contributions And Applications For Predictive Models, Adrian Jordan Koski
Theses and Dissertations
Beach closures and public health protection are confounded by analytical procedures that result in delays in notification of adverse water quality conditions and the lack of affordable analytical methods to identify pollutant sources. Attempts have been made to develop predictive frameworks using ancillary hydrometeorological data to statistically anticipate deteriorated water quality. Many urban coastal beaches are impacted by river runoff. In Kenosha Wisconsin, beach sanitary survey data from two beaches adjacent to the mouth of the Pike River were examined to ascertain whether simple river-lake mixing models identified river influence on coastal water quality and improved predictions of beach advisories. …
The Identification And Quantification Of Sewage Contamination In The Milwaukee Estuary, Hayley Templar
The Identification And Quantification Of Sewage Contamination In The Milwaukee Estuary, Hayley Templar
Theses and Dissertations
Sewage contamination from failing infrastructure and sewer overflows is a major environmental and human health concern in waterways, especially in urban communities bordering the Great Lakes such as Milwaukee, Wisconsin. Culture-based fecal indicator bacteria, such as Escherichia coli, enterococci, and fecal coliforms are traditionally used to indicate the presence of a human health risk due to fecal contamination. These indicators, however, fail to distinguish between sources of fecal contamination (human vs. non-human). Two human-specific fecal indicators, human Bacteroides and human Lachnospiraceae, were used to identify and quantify sewage contamination in the Milwaukee estuary, which discharges to Lake Michigan, as well …