Master of Science, University of Akron, 2021, Biology

Harmful algal blooms, most notably toxic cyanobacterial blooms, pose serious threats to water management and the environment. Copper algaecides, having a long history of use as a biocide in controlling algal blooms, is also toxic to other aquatic organisms and requires responsible application. With the majority of algal blooms occurring at a waterbody's surface, new copper formulations and application methods are continually developed to increase targeted action. Lake Guard Blue (BlueGreen Water Technologies Ltd.) was formulated as a floating copper product to increase upper water strata exposure. This product is conveyed as slow releasing and capable of movement in tandem with surface blooming algae through wind and water motion. Copper-based algaecide Lake Guard Blue was used in bench-scale experiments to determine efficacy in reducing cyanobacterial bloom densities. The product does not currently have EPA approval for use within the U.S. but is used elsewhere on the international market. Bench-scale experiments using environmentally sampled water with indigenous organisms were treated in triplicate with two dosages of Lake Guard Blue in parallel with EPA approved Cutrine Ultra (Arch Chemicals Inc.). Cyanobacteria populations were collected in the field at >10,000 cells/ml to be adjusted in the laboratory to 10,000 ±1000 cells/ml in accordance with the minimal action level required by the EPA for algaecide application. Lake Guard manufacture's recommended maximum dose of 17.8 lbs/acre was determined to contain more elemental copper than is allowable under current EPA regulations. A new full dose was calculated to 8.45 lbs/acre Lake Guard Blue for experimentation, translating to 2.49 mg/L Cu. Simultaneously, a copper equivalent dose of 0.94 mg/L Cu was established for Lake Guard Blue to match that of the recommended dose for comparative algaecide Cutrine Ultra. In total seven experiments were performed with five lakes sourced for water, two (open full item for complete abstract)

Committee: Teresa Cutright (Advisor); John Senko (Advisor); Donald Ott (Committee Member) Subjects: Biology; Environmental Science; Water Resource Management

Undergraduate Honors Program, Malone University, 2024, Honors Thesis

Several cyanobacteria species are known to synthesize various members of a family of photoprotective compounds known as mycosporine-like amino acids (MAAs). Although these UV-absorbing molecules appear to be good candidates for replacement of ineffective and potentially unsafe UV-filters approved by the Food and Drug Administration (FDA) as actives in United States sunscreens, their wavelength of absorbance is, on average, too short to provide adequate UVA protection. Moreover, extraction efficiencies of these compounds remain unrealistically low for commercial use, and purification techniques are expensive. This two-pronged research study takes aim at both barriers to wide-scale use of MAAs as sunscreen actives. First, Spirulina major, a cyanobacterium whose MAA production has not yet been elucidated in the available literature, was cultured under a variety of conditions in attempt to induce the biosynthesis of undiscovered MAAs with more desirable properties. Though no MAAs were isolated from S. major, HPLC chromatograms and UV-VIS absorbance spectra were consistent with the presence of a possible scytonemin derivative, another sunscreening compound of interest. Second, an attempt was made to prepare precursors to potentially desirable MAA analogs with the goal of furthering the current research on total chemical synthesis, which ultimately bypasses the problems associated with extraction of the natural product.

Committee: Jeffrey Goff PhD (Advisor); Kathryn Huisinga PhD (Committee Member); Steven Lane PhD (Committee Member) Subjects: Chemistry; Microbiology

Master of Science, The Ohio State University, 2023, Civil Engineering

Cyanobacteria harmful algal blooms (cyanoHABs) are of critical concern to drinking water treatment. Cyanobacteria, Microcystis sp. and Anabaena sp., are photosynthetic prokaryotic organisms that are dominant species in cyanoHABs and freshwater sources, including drinking water treatment reservoirs in Ohio. Due to increasing temperatures, nutrient-loading, and carbon dioxide emissions, the frequency and occurrence of cyanoHABs are more prevalent in water sources worldwide. CyanoHABs are nuisance organisms as the toxins produced negatively impact human health and recreational and economic resources. These toxins are also challenging to degrade in typical drinking water treatment. Commonly used algaecides such as copper sulfate can cause the release of intracellular toxins from cyanoHABs. In addition to the release of toxins, the chemicals can cause harm to non-target organisms that are beneficial to a healthy water ecosystem.Hydrogen peroxide (H2O2) is proposed as an environmentally friendly algaecide because of its rapid decomposition into water and oxygen. In addition, hydrogen peroxide selectively suppresses cyanobacteria. Non-target algal species, such as green algae, have antioxidant capacities that increase their defense against hydrogen peroxide. Ultrasound has also been proposed as an alternative to chemical algaecides for cyanoHAB reductions. Manufacturers of these ultrasound units promote their capability to reduce cyanoHABs by diminishing their buoyancy in the water column and limiting their ability to participate in photosynthesis. Varying sound pressures from ultrasound units have been reported in lab and field applications. We propose that applying hydrogen peroxide during ultrasound treatment will reduce the amount of chemical algaecide needed for the initial interaction for treatment or provide a synergistic effect on ultrasound treatment. Commercially available ultrasound units were purchased for this project. An anechoic chamber was built using sound (open full item for complete abstract)

Committee: Linda Weavers (Advisor); Natalie Hull (Committee Member); Allison MacKay (Committee Member) Subjects: Environmental Engineering

Master of Science, The Ohio State University, 2023, Environmental Science

As increases in frequency, duration, intensity, and geographical location of cyanobacterial harmful algal blooms (HABs) have been observed, more timely monitoring and targeted treatment of HABs and their cyanotoxins are crucial for freshwater bodies that are used for drinking water, recreation, and food production sources. To combat this, new management practices with tools that can handle the spatial and temporal variability of HABs are needed for water treatment plants and other sectors to ensure human health and ecosystem health. Unmanned Aerial Vehicles (UAVs), also known as drones, serve as one solution for near real-time monitoring of HABs. Recently, UAVs have gained increasing interest in research and development due to their many applications, efficiency in data collection, and the ability to customize these systems to specific needs. While research has shown that UAVs can accurately estimate chl-a and phycocyanin values -HAB indicators- little research has been conducted analyzing UAV imagery in parallel with microbiome data. In chapter 1, I summarize major relevant topics are summarized related to cyanoHABs, public health, and UAV systems. This provides a holistic view of current knowledge, methods, and limitations in cyanoHAB monitoring and detection. Chapter 2 seeks to explore the microbial community in parallel with environmental data, by analyzing seasonal dynamics, composition, and interactions within the microbial community in a hypereutrophic urban lake. In chapter 3, the feasibility and accuracy of using an UAV system for monitoring a hypereutrophic, urban water body was assessed. Objectives of this chapter include 1) proposing an UAV system and imagery processing framework that can be utilized by non-geospatial experts, 2) assess the accuracy of UAV derived chlorophyll-a values by regressing ground sampled fluorometer values and remotely sensed values, and 3) determine what algorithms and buffer sizes perform the best for cyanobacteria quantific (open full item for complete abstract)

Committee: Jiyoung Lee (Advisor); Joseph Ortiz (Committee Member); Motomu Ibaraki (Committee Member); Rongjun Qin (Committee Member) Subjects: Environmental Science; Microbiology

Master of Science, The Ohio State University, 2023, Environmental Science

Cyanobacteria harmful algae blooms are an issue of increasing concern, especially in source water that is used for drinking water. Several treatment technologies have been proposed for mitigating these blooms. Low power ultrasonic units are used as a treatment technology for treating and decreasing blooms in source water. Currently, there lacks an understanding of how cyanobacteria interacts with low power ultrasonic units and the mechanism of treatment, if there is one. The goal of this work aimed to discern how cyanobacteria cells may be impacted by low power ultrasonic units. We examined a specific mechanism of interaction, called sonoporation. We employed cell stains, a flat plate ultrasonic transducer, an anechoic chamber, and flow cytometry to elucidate if sonoporation was occurring in these instances. The study considered Microcystis sp. and Anabaena sp., which are a unicellular and filamentous type of cyanobacteria, respectively. Our first objective was to develop a cell staining technique that could be used to study sonoporation in cyanobacteria using flow cytometry. Our goal was to be able to assess increased permeabilization of samples. Cyanobacteria exhibit natural fluorescence which can interfere with the fluorescence emitted by certain cell stains. The specific cell stains used for our work were cell permeant and cell impermeant. Cell permeant stains enter into all cells in a population while impermeant stains only enter into cells with a damaged membrane, or if the membrane were transiently permeable, such as is the case with sonoporation. Previous studies have not used combinations of cell permeant and cell impermeant stains compatible with natural cyanobacteria fluorescence to detect viability over long term experiments using flow cytometry. Five different sets of cell permeant and cell permeant stains were tested with Microcystis sp. We found that the cell permeant stain DAPI and the cell impermeant stain SYTOX Green worked for examining Micro (open full item for complete abstract)

Committee: Linda Weavers (Advisor); Natalie Hull (Committee Member); Allison MacKay (Committee Member) Subjects: Engineering

Doctor of Philosophy, Miami University, 2023, Biology

Cyanobacteria harmful algal blooms (CyanoHABs) are an increasing threat to freshwater lakes and reservoirs but are difficult to predict in occurrence and severity. Excess loading of terrestrial dissolved organic matter (tDOM), which alters nutrient and light availability, may be contributing to CyanoHABs but has not been tested directly. The purpose of this dissertation is to provide new insights into whether tDOM contributes to CyanoHABs. This work tested the hypothesis that increases in tDOM favors the functional traits of toxic Cyanobacteria, by altering nutrient and light availability. To test the hypothesis, I first used water from three different lakes and measured changes in Cyanobacteria biomass, as chlorophyll-a (Chl-a) and phycocyanin, and toxin production (Chapter 1). Using a bottle experiment and factorial design (2 x 5), I alternated added tDOM (none vs tDOM added), added nutrients (none vs low N: P vs high N: P), and added N form (added NH4 vs urea). One consistent finding across all three trials was that adding tDOM increased phycocyanin and mediated the response of biomass and toxin production to added nutrients. In a separate bottle experiment, I used water from the same three lakes to test whether the source of tDOM, which can vary in quality, contributes to CyanoHABs (Chapter 2). A factorial design (4 x 2) was used alternating added tDOM source (none vs manure vs crop vs wetland leachate) and added nutrients (none vs high N: P with N as NH4). A consistent finding was that varying tDOM source effects Cyanobacteria biomass and toxin production, and that tDOM source mediates the response of Cyanobacteria to added nutrients. Finally, I tested the phytoplankton community response to a simulated entrainment event when DOM and nutrient rich water was transposed from the deep water to the surface, using a comparative lake experiment (Chapter 3). I used microcosm bags, incubated under natural conditions, with three treatments of water from 1) epilimnion al (open full item for complete abstract)

Committee: Craig Williamson (Advisor); Annette Bollmann (Committee Member); Michael Vanni (Committee Member); Lesley Knoll (Committee Member); Ann St. Amand (Committee Member); Thomas Fisher (Committee Member) Subjects: Aquatic Sciences; Biology; Ecology

Master of Science (MS), Wright State University, 2023, Earth and Environmental Sciences

Grand Lake St. Marys is the largest (52 km2) inland lake in Ohio, USA, and receives high nutrient loadings (90th percentile for total nitrogen (N) and phosphorus (P) concentrations in the USA) from a watershed dominated by agricultural row-crops and livestock production. Eutrophication has led to cyanobacterial harmful algal blooms, dominated by non-N2 fixing Planktothrix, that persist year-round, including in winter months. In summer 2020 and 2021, multiple treatments using P-binding agents within a 3.5 ha swimming enclosure were conducted to remove excess dissolved P from the water column. The objective of this study was to examine pre-and-post treatment biogeochemical and physicochemical conditions in contrast to the surrounding lake, in addition to evaluating anomalous conditions that led to removal of the lake's no-contact advisory for the first time in 12 years. In four out of five treatments across both years, total P and chlorophyll-a (chl-a) values were higher three weeks post-treatment within the treated area, indicating failures of the treatments to reduce biomass long-term. The harsh winter of 2020-2021, along with a dry Spring 2021, led to large, temporary reductions in algal biomass and toxicity and sediment oxygen demand, and allowed for denitrifying bacteria to remove excess N from the water column. However, chl-a levels returned to > 300 µg L-1 by July 2021. This study, along with previous studies regarding failures of treatments using P-binding agents to reduce algal biomass and toxicity long-term, provide further evidence that reducing watershed N and P loads is likely the only long-term solution to mitigating eutrophication and cyanobacteria blooms in GLSM.

Committee: Silvia E. Newell Ph.D. (Advisor); Stephen J. Jacquemin Ph.D. (Committee Member); Mark J. McCarthy Ph.D. (Committee Member) Subjects: Environmental Health; Environmental Science; Environmental Studies; Water Resource Management

MS, University of Cincinnati, 2023, Engineering and Applied Science: Computer Science

The use of advanced data collection and visualization tools has opened up many opportunities for the best possible use of information in scientific research, management, and decision-making. Interactive data visualizations make it easier to access and interpret large datasets, allowing for new knowledge to be discovered and hypotheses to be formed, leading to a deeper understanding of data. With web technologies and standards, there are now more open-source software libraries available for creating web applications with data. The internet is proven to be very important as it makes data and models more accessible while aiding collaboration among different researchers. This thesis puts forward a solution to create a web application to help with cyanobacteria research by collecting and displaying data while combining academic software development practices with industry standards. The approach used for this thesis combines design thinking methods with agile methodologies during develop- ment. Open-source software is used exclusively in order to achieve transparency, accessibility, and easy updates in the future.

Committee: Arthur Helmicki Ph.D. (Committee Chair); Nan Niu Ph.D. (Committee Member); Victor Hunt Ph.D. (Committee Member) Subjects: Computer Science

Master of Science, The Ohio State University, 2023, Environmental Science

Anthropogenic impacts result in deteriorating drinking water source quality and the jeopardization of the environment and public health. The spread of antibiotic resistant (AR) bacteria and genes (ARGs) both clinically and in the environment, as well as the expansion of Cyanobacterial harmful algal blooms (cyanoHABs), have received attention for their impacts on public health. These two issues occur at the nexus of a changing climate. There is a need to address the combined impacts and interactions between these two historically independent issues in the environment. The possible role of Cyanobacteria in the environmental resistome should not be discounted. Many Cyanobacterial taxa have mobile and plastic genomes, account for massive proportions of freshwater biomass during cyanoHABs, and have been shown to possibly host ARGs. Viruses, particularly the phages that infect bacteria, are another emerging research topic linked to both issues. In the case of Cyanobacteria, Cyanophages are involved in the dynamics of cyanoHABs and are frequently suggested for use as Cyanobacterial biocontrols in controlled circumstances. In the case of AR, phages are studied as possible carriers of ARGs involved in the transduction of ARGs between bacteria. Therefore, research gaps relating to these issues and their co-occurrences are targeted in this thesis, which focused on two major drinking water sources from two historically cyanoHAB-impacted regions. One is Lake Erie, known for Microcystis-predominant cyanoHABs and the 2014 drinking water crisis. The other is Grand Lake St. Marys, known for persistent Planktothrix and high microcystin levels. In Chapter 1, a review is included referencing the current knowledge and literature on the topics and the two locations. In Chapter 2, the major objectives were to first monitor Cyanobacterial community trends in Lake Erie and GLSM drinking water sources and compare the two locations; second, to characterize the resistome in drinking water so (open full item for complete abstract)

Committee: Jiyoung Lee (Advisor); Stephen Abedon (Committee Member); Richard Dick (Committee Member) Subjects: Bioinformatics; Environmental Science; Freshwater Ecology; Microbiology; Public Health

Master of Science, The Ohio State University, 2023, Environment and Natural Resources

Phytoplankton respond to environmental conditions through specialized adaptations and may proliferate to cause harmful algal blooms (HABs). Nutrient enrichment, largely linked to land-use, has been studied extensively in lakes, but less in streams and rivers. I investigated the influence of nitrogen (N), phosphorus (P), and environmental variables on phytoplankton community dynamics in streams and reservoirs in seven catchments representing a gradient of agricultural, forested, and mixed land uses in the upper Ohio River Basin. The main objectives of this study were to (1) examine the spatiotemporal variability of phytoplankton biomass and relative abundance and (2) identify environmental drivers associated with phytoplankton community structure. In reservoirs, total phosphorus (TP) ranged from 0.001 to 1.50 mg/L and did not differ among catchments, whereas total nitrogen (TN) ranged from 0.084 to 1.91 mg/L and differed significantly among catchments. Total chlorophyll a ranged from 2.56 to 150 µg/L, with Indian Lake exhibiting the highest concentrations (150 chl a µg/L). Cyanobacterial chlorophyll a concentrations were highest in Indian Lake (143.2 chl a µg/L) and positively correlated with percentage agriculture and ammonium concentrations, and were negatively correlated with total phosphorus and TN:TP ratio. There were noticeable differences in the relative abundance of phytoplankton taxonomic groups across catchments and years. Percentage agriculture was identified as a strong predictor of total and cyanobacteria chlorophyll a concentrations. In streams, TP ranged from 0 to 1.32 mg/L, and TN ranged from 0.093 to 4.72 mg/L. Indian Lake exhibited the greatest total chlorophyll a concentrations, with the highest concentrations of both cyanobacterial (76.1 µg/L) and chlorophyte (30.8 µg/L) chlorophyll a. Non-metric multidimensional scaling (NMDS) and permutational multivariate analysis (PERMANOVA) showed differences in phytoplankton communities between years and amo (open full item for complete abstract)

Committee: Mazeika Sullivan (Advisor); Lauren Pintor (Committee Member); Kaiguang Zhao (Committee Member) Subjects: Biology; Ecology; Freshwater Ecology; Limnology

Master of Science in Engineering, University of Akron, 2023, Chemical Engineering

Algal cyanobacteria can produce cyanotoxins in the surface water. The rise in cyanotoxins occurrence and concentration threatens animals and humans, making them a global environmental challenge. Powdered activated carbon (PAC) is a non-reactive and cost-effective option for the adsorption of cyanotoxins. The extent of adsorption is influenced by the properties of PAC, toxins, and surface water. This project focused on the removal of varying concentrations of microcystin-LR (MC-LR, 0.3, 1.6, and 20 μg/L) and saxitoxin (STX, 0.3 and 1.6 μg/L) with three different PAC sources. Experiments were performed with distilled water (pH 6 and 9) and natural water (pH 6, 8, and 9) when MC-LR and STX were present alone and simultaneously. Mixing rates of drinking water plant were scaled down to lab scale to replicate the rapid mix-flocculation by maintaining the same velocity gradient using a gang mixer. Additional tests were performed to find PAC's point of zero charge (pHPZC) to determine its overall surface charge variation with pH, which could affect adsorption based on cyanotoxin's charge. Source of PAC impacted removal of toxins. For instance, the wood-lignite-based PAC from CarbPure (CP) adsorbed more MC-LR than the bituminous coal-based PAC purchased from Calgon Carbon (CC) (p<0.05). Depending on the initial concentration, CP adsorbed 49-87% MC-LR in distilled water and 60-84% in raw water. CC only adsorbed 20-60% MC-LR from distilled water and 11-21% from raw water. In raw water across all pH and concentration combinations, STX removal was 16-80% with CP and 31-46% with CC. An experiment performed on 0.3 μg/L STX in distilled water with an additional PAC, Aquasorb (AS), had a removal trend of CP > AS > CC. The presence of multiple sources (AS and CP) may have enhanced adsorption. CP adsorbed (14-77%) more STX in distilled water than CC (21-49%) and AS (16-68%). When toxins were present simultaneously, CP effectively removed 48-72% MC-LR and 30-66% STX, depending upon the (open full item for complete abstract)

Committee: BI-MIN ZHANG NEWBY (Committee Member); LU-KWANG JU (Committee Member); TERESA CUTRIGHT (Advisor) Subjects: Chemical Engineering; Civil Engineering; Environmental Engineering

Master of Science (MS), Bowling Green State University, 2023, Biological Sciences

Cyanobacterial harmful algal blooms are ubiquitous globally and can have enormous impacts on the environment, economy, and human health. These blooms have the potential to produce toxins such as microcystin (MC), cylindrospermopsin (CYN), and saxitoxin (STX). Currently, the standard method for toxin testing is by an Enzyme Linked Immunosorbent Assay (ELISA). This method is time consuming; LightDeck Diagnostics has developed a rapid and portable multiplexed assay to simultaneously test for MC, CYN, STX as an alternative to ELISA testing. During the summer of 2021, LightDeck's duplexed MC-CYN assay was successfully field validated in Sandusky Bay. A method of portable lysis was also tested but is undergoing further development prior to being used in additional testing. During the summer of 2022, a triplexed version of the LightDeck cartridge (MC-CYN-STX) was field validated in both Sandusky Bay and Springbrook Lake in Whitehouse, Ohio. The STX assay successfully detected toxin, however the triplexed MC assay did not perform as well as the previous duplex formulation. Additionally, toxin concentrations were correlated with water quality parameters and nutrients in both lakes to investigate potential environmental drivers of toxicity during bloom events. The LightDeck assay was also used as part of a research cruise in the Winam Gulf, Kenya. Though ELISA remains the gold standard for toxin detection, the LightDeck assay could be a valuable tool in monitoring and reporting toxin in water bodies that people interact with, whether they be recreational lakes or water that the community relies on for daily functions as demonstrated in the case of the Winam Gulf.

Committee: Christopher Ward Ph.D. (Committee Chair); George Bullerjahn Ph.D. (Committee Member); Sarah Bickman Ph.D. (Committee Member) Subjects: Biology

Master of Science, University of Toledo, 2022, Civil Engineering

The occurrence of harmful algal blooms (HABs) in many freshwater systems has been a significant problem for surrounding cities for decades especially as potable water supply. Algaecide applications are known as one of the effective management tactics for rapidly controlling HABs in the source waters. However, excess applications have been shown to damage the bacteria cells and to release intracellular organic matter (IOM), which is difficult to be treated during the conventional water treatment processes. There are previous studies regarding algaecide applications in terms efficacy under different conditions, however limited studies on how algaecide treatments affect algal organic matter release (AOM). Four different USEPA-registered algaecides, two copper-based (SeClear® and Algimycin® PWF) and two peroxide-based (PAK® 27 and Oximycin® P5), were selected for this study based on preliminary results of commercial algaecide testing. The efficacy of algaecides and the release of AOM from the damaged cells were tested for 108 hours in a prepared monoculture of Microcystis aeruginosa. The efficacy was again tested at the same cell concentration of Microcystis aeruginosa in mixed culture at the selected doses and the exposure time from the single culture. Total chlorophyll-a (chl-a) and total phycocyanin concentrations were monitored to evaluate cyanobacterial health and dissolved organic carbon (DOC), dissolved toxin, and dissolved phycocyanin concentrations were monitored to analyze the cell damage. A Parallel Factor Analysis (PARAFAC) model was built using the collected Excitation-Emission Matrix (EEM) spectra of the samples under different algaecide treatment types and concentrations to characterize and quantify the aqueous AOM during the treatment. Three possible components were characterized: Soluble microbial by-products (SMPs)-like, tyrosine-like, and humic-like materials. This research advances the understanding of impacts of HABs management using algaecides. The (open full item for complete abstract)

Committee: Youngwoo Seo (Committee Chair); Defne Apul (Committee Member); Daewook Kang (Committee Member) Subjects: Engineering

Master of Science, University of Toledo, 2022, Civil Engineering

Globally, harmful algal blooms (HABs) have increased in frequency due to many factors like eutrophication, increased temperature, and ecosystem instability. Typically, algaecides are used to control HABs, some of which are formulations of hydrogen peroxide and copper sulfate. Unfortunately, traditional HAB control methods using algaecides have many downsides including requiring repeated applications and adverse environmental externalities. Cyanophage have been shown to be effective at suppressing cyanobacterial growth and have been suggested to be effective after algaecide application, however this idea has yet to be tested. Given the shortcomings of chemical-based algaecides, this experiment explored the synergistic impact of cyanophage Ma-LMM01 and the low dose algaecide, Pak-27. In the combined experiment low-dose Pak-27 was more effective at suppressing growth when combined with cyanophage Ma-LMM01 and application of the low-dose Pak-27 did not impact the cyanophage's ability to lyse the cells when applied before cyanophage inoculation. These results provide insight in the potential for a biological based treatment method, and the creation of a “cyanophage cocktail” that contains many different strains of cyanophage with different host preferences is an emerging research opportunity.

Committee: Youngwoo Seo (Committee Chair); Dae-Wook Kang (Committee Member); Katelyn McKindles (Committee Member) Subjects: Engineering

Master of Science, The Ohio State University, 2022, Civil Engineering

As source waters for Ohio drinking water treatment plants are increasingly subject to algal blooms, treatment utilities must employ methods to remove resulting cyanotoxins. Cyanotoxins exist in two forms: intracellular and extracellular. Intracellular toxins are contained within a living cyanobacteria cell, whereas extracellular toxins are dissolved in water after cell death. Treatment for each form of cyanotoxin varies and can result in a conflicting outcome. Strategies like pre-oxidation, which are employed to remove extracellular toxins, can adversely affect the living cyanobacteria cells. If the oxidant damages the cell wall, the cyanobacteria cell can lyse and release toxins. Thus, there is potential for higher levels of extracellular toxins later in the drinking water treatment process. Our work aimed to discern where cyanobacteria cells are subjected to stressors that cause damage within the drinking water treatment process. We employed a bench- scale simulation to focus on chemical treatments and mechanical shear that occur during the water treatment process. The study considered Microcystis (MC) and Planktothrix (PT), which are two types of microcystin-producing cyanobacteria that are prominent in Ohio with different morphological characteristics. Our first objective was to understand the effect that chemical oxidant treatments have on cyanobacteria cells. Potassium permanganate and sodium hypochlorite (chlorine) are oxidants that are used in water treatment for their destructive capabilities. Treatment utilities often employ pre-oxidants near the water intake to remove extracellular toxins, but there is concern that pre-oxidation damages cells and leads to release of additional cyanotoxins. In this study, we tested different dosages of chlorine and permanganate on cyanobacteria cells to determine the impact of these oxidants on cell integrity. We found that chlorine caused complete lysis by a dosage of 2 mg/L for both species, but PT showed higher s (open full item for complete abstract)

Committee: Allison MacKay (Advisor); John Lenhart (Committee Member); Natalie Hull (Committee Member) Subjects: Civil Engineering; Environmental Engineering

Master of Science in Engineering, University of Akron, 2022, Civil Engineering

Cyanotoxins produced from cyanobacteria dominated harmful algal blooms (cHABs) are on the rise. This increase in toxins poses a threat to ecosystems as well as drinking water systems. This thesis evaluated the treatment of Anatoxin (ATX) and Saxitoxin (STX) when alone or with Microcystin (MC) using conditions of the Alliance drinking water treatment plant. The two treatments of focus were powdered activated carbon (PAC) added during the flocculation phase, which was evaluated in distilled (DI) water and raw source water, and chlorination in the disinfection phase evaluated in post-filtration water. The impact of pH was considered for both treatments. The impact of cyanobacteria cells in the PAC treatment was also assessed. STX showed removal of up to 81% in DI water, this best condition was achieved for the pH of 8 and 1.6 μg/L. The same trend was observed in raw water with a removal of up to 79% when STX was alone at pH 9. MC showed no impact on STX removal since removals were also in the 70-78% range (p>0.05). For ATX, the removal in DI water was minimal with the highest being 35% at pH 6 at a concentration of 20 μg/L. In general, a lower pH showed higher removal. In raw water at the same concentration, the removal went up to 80%. pH changes did not seem to have an impact on the removal. The addition of a higher concentration of MC seemed to improve the removal of ATX, this could be due to the charges of each of the toxins. The addition of cells did inhibit the removal of ATX, but not of MC. During chlorine experiments, STX had higher removals at higher pH levels. The highest removal was 57% at pH 9 with a concentration of 0.3 μg/L and MC concentration of 1.6. This corroborated that a higher concentration of MC led to higher removal. Only one ATX experiment was done since it had been shown before to not be very effective. ATX was removed by 38% at pH 6. Lastly, a concurrent study determined removal efficiencies for PAC and chlorine for the City of Akron, O (open full item for complete abstract)

Committee: Teresa Cutright (Advisor); Richard Einsporn (Committee Member); Nariman Mahabadi (Committee Member) Subjects: Civil Engineering; Environmental Engineering; Water Resource Management

Master of Science in Engineering, University of Akron, 2022, Civil Engineering

Cyanobacteria can produce cyanotoxins such as microcystin, saxitoxin, and anatoxin-a. These toxins are harmful to humans and other animals. This project focused on the removal efficiency of saxitoxin and anatoxin-a alone, as well as in the presence of microcystin-LR, by either powdered activated carbon (PAC) or chlorine. Furthermore, removal efficiency of these toxins by PAC was also determined in the presence of added active cyanobacterial cells in source water. PAC experiments were performed using distilled water and source water from the City of Akron Drinking Water Treatment Plant, located in northeast Ohio. pH had a significant impact on PAC results. Saxitoxin showed increased removal at higher pH levels in both distilled and source water. For instance, at pH 9 the removal was 48% in distilled water and 46-76% in source water, whereas it was 0-21% at pH 6 in distilled water and 23-47% in source water. Conversely, anatoxin-a showed increased removal at lower pH levels in distilled water, with 30-37% removal at pH 6 compared to 10-26% at pH 9 in distilled water. However, anatoxin-a removal increased at higher pH in source water with microcystin-LR added. For example, there was 31% removal at pH 6 compared to 65% and 59% removal at pH 7and 9, respectively. Microcystin-LR, when combined with either toxin, showed increased removal at higher pH levels in source water. pH 6 resulted in 9-45% removal and pH 9 resulted in 54-91% removal of microcystin-LR. Furthermore, the initial concentration of saxitoxin was a major factor, with the larger concentration (1.6 μg/L) resulting in 39% more removal in distilled water. On the other hand, in source water, the smaller STX concentration (0.3 μg/L) had 30% more removal. Finally, for PAC, the addition of cyanobacterial cells did not affect saxitoxin removal, however microcystin-LR removal decreased, with at least 14% reduction in removal efficiency across all pH levels. Chlorine experiments were performe (open full item for complete abstract)

Committee: Teresa Cutright (Advisor); Nariman Mahabadi (Committee Member); Richard Einsporn (Committee Member) Subjects: Civil Engineering; Engineering; Environmental Engineering; Environmental Health; Environmental Science; Environmental Studies; Molecules; Physical Chemistry; Water Resource Management

Doctor of Philosophy, Miami University, 2022, Microbiology

The impact of ever-increasing levels of CO2 emissions on climate change has driven the research of sustainable and renewable energies. Microbial production of chemicals is considered a viable green alternative to conventional petroleum-based processes. With advancements in synthetic biology, cyanobacteria have emerged as an alternate carbon capture system to reduce the carbon footprint of chemical production. Harnessing solar energy and concentrating CO2 into varied native or non-native carbon compounds is a natural phenomenon in these photosynthetic prokaryotes, making them attractive sustainable bioproduction platforms. Currently, cyanobacteria-based bioproduction platforms are challenged with low productivities compared to conventional heterotrophic hosts. Thus, research directed at photosynthesis enhancement to support a robust carbon metabolic rewiring is needed to improve direct CO2 conversion into desired compounds. In this dissertation, the cyanobacterium Synechococcus elongatus PCC7942 was used to first understand how it naturally rewires carbon metabolism for optimal photosynthetic performance. Limonene synthesis was further engineered in cyanobacteria to evaluate its capacity as a non-native carbon sink. Compared to many heterotrophic platforms, the direct CO2-to-limonene production in cyanobacteria showed low productivity, which was attributed to the low thermodynamic driving force due to the low CO2 assimilation rate. Thus, alternative approaches targeted at relieving thermodynamic limitation were employed to enhance the substrate availability and thereby, limonene titer. The limonene productivities were significantly improved by using sigma factor engineering and consortium-strategy. The findings in this dissertation provide a new perspective to improve biochemical production using cyanobacteria and facilitate a better understanding of the source and sink synergy in secondary metabolite biosynthesis.

Committee: Xin Wang (Advisor) Subjects: Microbiology

Master of Science (MS), Bowling Green State University, 2022, Biological Sciences

Chautauqua Lake is a eutrophic lake located in western New York that is frequently impaired by cyanobacterial harmful algal blooms (cHABs). cHABs generally occur in systems with high nutrient concentrations, but factors including lake morphology and temperature also contribute to growth and development of cyanobacteria. cHABs often result in production of hepatotoxins (e.g., microcystins) and neurotoxins (e.g., saxitoxins) that are harmful to living organisms. This study focuses on examining the environmental drivers of toxin production in Chautauqua Lake through nutrient addition experiments to determine which conditions favor toxin production. Findings will help in lake management efforts, specifically by reducing toxin concentrations. This project consists of long-term nutrient diffusing substrata trays deployed at the benthos and short-term nutrient amendment bottle experiments. The trays were deployed in two-week to month long periods from July to October 2020, and the bottle experiments were performed in 2020 and 2021. It was found that nutrient limitation in Chautauqua Lake changes through the summer season corresponding to taxa present in the bloom. Overall, when Gloeotrichia was the dominating taxon in 2020, nutrient additions did not influence toxin concentrations, mcyE copies, or sxtA copies in the water column. In contrast, 2021 data demonstrated phosphorus (P) limitation. However, when Microcystis was the dominating taxon in the bloom, nitrogen (N) limitation was observed in the water column in both years. The benthos in 2020 exhibited changing nutrient limitation throughout August to October, where data suggest P may be limiting chlorophyll-a in August through September, and in September through October data suggests dual N and P limitation.

Committee: Christopher Ward Ph.D. (Advisor); Dianne Greenfield Ph.D. (Committee Member); George Bullerjahn Ph.D. (Committee Member) Subjects: Ecology; Environmental Science; Freshwater Ecology; Microbiology

Master of Science, Miami University, 2021, Microbiology

Environmental salt concentration is an important abiotic factor indicative of environmental change and stress. As the environment changes the productivities of plants plummet thus, draining resources of the agriculture industry. Cyanobacteria are photosynthetic organisms that utilize both light and CO2 for their metabolism. Their evolutionary similarities with plants coupled with the ability to be used as a microbial feedstock make them ideal model organisms. Synthetic biology utilizes rational engineering approaches to increase the biomass and sucrose productivity of Synechococcus elongatus (Se) PCC 7942. However, these approaches are limited by a plateau effect seen in product synthesis and exhaustion of the cell. Through accelerated evolution, it is possible to induce mutations under specific stressors to drive distinct adaptations. Employing a hypermutator strain, we evolved the cells in increasing concentrations of salt and found increasing sucrose productivity following each round of evolution. Additionally, one evolved strain, Se2-192, exhibited increased salt tolerance and growth when re-exposed to salt. This project provides evidence of salt adaptation in S. elongatus PCC 7942 strains when evolved in high salt concentrations. Furthermore, the mutants produced in these studies can be used to identify adaptative mechanisms employed by the cell to deepen our understanding of metabolic plasticity.

Committee: Xin Wang Dr. (Advisor); Luis Actis Dr. (Committee Member); Donald J. Ferguson Dr. (Committee Member) Subjects: Microbiology