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Articles 1 - 28 of 28
Full-Text Articles in Environmental Microbiology and Microbial Ecology
Exploring Competitive Dynamics Between Pseudomonas Baetica And Salmonella In A Polymicrobial System, Braxton E.M. Stout
Exploring Competitive Dynamics Between Pseudomonas Baetica And Salmonella In A Polymicrobial System, Braxton E.M. Stout
Electronic Theses and Dissertations
The global rise in antimicrobial resistance has catalyzed a greater focus on polymicrobial research aimed at characterizing microbial interactions and uncovering new therapeutic strategies. Though it has long been of interest, environmental soil-derived bacteria remain largely under-represented in research and thus uncharacterized in this field. This project aimed to identify soil microbes that display inhibitory mechanisms to potential nosocomial pathogens. Soil sample S1S3-2 displayed inhibitory phenotypes toward numerous bacteria and was identified as Pseudomonas baetica. In both planktonic and biofilm growth, P. baetica was able to inhibit Salmonella arizonae through a contact-dependent and temperature-dependent manner. Screening of a transposon insertion …
The Impacts Of Management Practices On Industrial Hemp Chemistry, Physiology, And Microbiome Ecology., Allison Marie Rietman
The Impacts Of Management Practices On Industrial Hemp Chemistry, Physiology, And Microbiome Ecology., Allison Marie Rietman
Electronic Theses and Dissertations
Agroecology incorporates ecology and agronomy to inform crop management. Industrial hemp (Cannabis sativa L.) is a prime system to investigate agroecological questions because it has only recently been authorized for commercial cultivation and its sensitivity to biotic and abiotic stressors is unresolved. Here, I investigate how some conventional management choices, including the application of fungicide, plastic mulch, and irrigation, impact the physiology, chemistry, and microbial ecology of industrial hemp. Overall, I found that industrial hemp can be both resilient and resistant to these stressors, an important development for the industry. In Chapter II, I tested the impacts of fungicide application …
The Relationship Between Salvinia Molesta Infestation And The Microbial Ecology Of Wetlands At Caddo Lake, Tx, Usa, Martin Hadsell
The Relationship Between Salvinia Molesta Infestation And The Microbial Ecology Of Wetlands At Caddo Lake, Tx, Usa, Martin Hadsell
Electronic Theses and Dissertations
Wetlands are known to host many beneficial geochemical processes such as nutrient cycling and carbon sequestration. These processes are primarily driven by the microbial communities within a wetland. The establishment of non-native invasive species within wetlands has the potential to alter the once beneficial functionality of wetland microbial communities due to the sensitivity microbes have towards environmental changes. Because of this, several metagenomic studies have been conducted to assess microbial community response to aquatic plant invasion; however, there haven’t been any studies researching the influence of Salvinia molesta (D.S. Mitch.), commonly known as Giant Salvinia, on microbial communities. The goal …
Characterization Of A Novel Metalloid Reductase Outer Membrane Porin Rara From Sulfurospirillum Barnesii Ses-3, Narthana Jeganathar Kanmanii
Characterization Of A Novel Metalloid Reductase Outer Membrane Porin Rara From Sulfurospirillum Barnesii Ses-3, Narthana Jeganathar Kanmanii
Electronic Theses and Dissertations
Sulfurospirillum barnesii SES-3 is a gram-negative epsilon proteobacterium that grows anaerobically by coupling the oxidation of lactate to the reduction of arsenate. Previous work on metal and metalloid metabolism in S. barnesii had identified a redox active protein, designated RarA that when provided an artificial electron donor (i.e., reduced methyl viologen, FMN, or NADH), could reduce a variety of substrates, including arsenate, selenate, selenite, nitrite, and even phosphate. The enzyme’s inferred amino acid sequence showed weak similarity (30%) to outer membrane porins with homologs found in only certain species of Sulfurospirillum. Further, the enzyme did not contain cysteine residues …
Breaking Virulent: The Coincidental Evolution Of Virulence Factors In Bacteria., Rhiannon Emmanuelle Cecil
Breaking Virulent: The Coincidental Evolution Of Virulence Factors In Bacteria., Rhiannon Emmanuelle Cecil
Electronic Theses and Dissertations
Understanding how innocuous organisms can evolve to be pathogenic to humans is of increasing global concern. Further, understanding how existing pathogens may evolved to be more virulent is also vital to our ability to provide healthcare to people afflicted with diseases that promote chronic bacterial infections, such as cystic fibrosis. With the rise of antibiotic resistance in both bacteria and fungi it is paramount that new therapeutics are identified. Understanding what mutations occur that result in increased virulence in microbes can potentially provide new targets for antimicrobial drugs to combat antibiotic resistance. The Coincidental Evolution Hypothesis is a fundamental hypothesis …
Inhibiting Survival Of Salmonella During Desiccation Through The Use Of Naturally Occurring Signals, Joseph Headrick
Inhibiting Survival Of Salmonella During Desiccation Through The Use Of Naturally Occurring Signals, Joseph Headrick
Electronic Theses and Dissertations
A rising problem in agriculture is the increase of antibiotic-resistant Salmonella cases associated with chicken eggs, which transmit infection to humans. To counter this, new approaches to combat Salmonella in chickens and desiccated on eggshells are vital in the prevention of human foodborne illness. Disrupting signaling pathways with naturally occurring compounds provides a potential novel avenue for prevention of Salmonella infections, as this would disrupt sensing of these environments and inhibit subsequent optimal gene expression. Starting with signals identified in previous studies, salicylic acid was found to inhibit Salmonella desiccation survival on both eggshells and plastic. To expand upon this, …
Understanding Human Gut Bacterial Interactions And Their Role In Colonization Resistance Against Clostridioides Difficile Using Mini-Bioreactor Array And Caenorhabditis Elegans As Model Systems, Achuthan Ambat
Electronic Theses and Dissertations
No abstract provided.
Evaluation Of Welded And Polished Stainless-Steel Surfaces In Supporting Sporeformer Biofilms In Dairy Plants, Taghreed Almalki
Evaluation Of Welded And Polished Stainless-Steel Surfaces In Supporting Sporeformer Biofilms In Dairy Plants, Taghreed Almalki
Electronic Theses and Dissertations
No abstract provided.
Novel Signal Sequences And Fusion Partners For Paratransgenesis In Asaia, Christina Grogan
Novel Signal Sequences And Fusion Partners For Paratransgenesis In Asaia, Christina Grogan
Electronic Theses and Dissertations
Mosquitoes transmit many pathogens that cause human disease. One such disease, malaria, is caused by parasites in the genus Plasmodium, infecting over 200 million people and killing over 600,000 per year. Current strategies to control vector-transmitted diseases are increasingly undermined by mosquito and pathogen resistance. Research has turned to additional and novel methods of control, such as altering the microbiota of the vectors. In this method, called paratransgenesis, symbiotic bacteria are genetically modified to affect the mosquito’s phenotype by engineering them to deliver antiplasmodial molecules into the midgut to kill parasites. These molecules must be released by the …
Effect Of Mycorrhizae Inoculation On The Growth And Success Of Three Taxodium Distichum Hybrids In Saline - Impacted Coastal Soils, Elif Ilhan
Electronic Theses and Dissertations
In 2008, Galveston Island was severely impacted by Hurricane Ike, resulting in high salt deposition in the soil and groundwater. This caused a loss of many native plant species. A study was initiated to determine effective ways to promote the growth conditions of three bald cypress genotypes (Taxodium distichum var distichum and Taxodium distichum var mexicanum crosses) in salt-affected soils. The treatments applied were mycorrhizae inoculation, fertilizer application, and a combination of mycorrhizae inoculation and fertilizer application. A total of sixty (60) trees planted in plots of three rows and divided into five randomized replication blocks of four treatments …
Microbial Communities And Nitrogen Dynamics In Prairie And Cropland Soils, Bikram Kumar Das
Microbial Communities And Nitrogen Dynamics In Prairie And Cropland Soils, Bikram Kumar Das
Electronic Theses and Dissertations
Soil microbial communities are affected by many factors, such as soil nitrogen (N) and the quantity of grass-root exudates, changing seasons, fertilization method, plant diversity, and their origin. This holds for both natural and fertilized soils. This research was intended to expand the current understanding of soil microbial interactions associated with ecological functions. The objectives of the research were (I) to characterize prokaryotic soil communities, estimate functional potential, and quantify nitrogen cycle-associated prokaryotic gene expressions across three phases of the growing season, (II) to explore the diazotrophic community composition in a natural system using nifH sequencing as well as 16S …
Characterizing The Dormancy And Repair Of A Circumneutral Passive Remediation System Receiving Iron And Sulfate-Rich Amd, Garrett Struble
Characterizing The Dormancy And Repair Of A Circumneutral Passive Remediation System Receiving Iron And Sulfate-Rich Amd, Garrett Struble
Electronic Theses and Dissertations
The Wingfield Pines remediation system is a ~20-acre circumneutral, gravity-fed system constructed in 2009 to passively remediate Fe from an ~2000 gallon/minute effluent. In 2017, a fracture to the system’s underground cavern caused the AMD effluent to bypass the system, flowing directly into Chartiers Creek and leaving the system decommissioned between 2017-2019. Soil slurry and water samples were collected in the weeks prior to the system’s reinstalment in September 2019 through January 2020 in order to determine the effect of the repair on remediation efficiency and microbial community composition. This study acted as the first to describe the temporary decommissioning …
Characterization Of The Rumen Bacterial Communities Of Bison Heifers Fed A Grass-Based Diet Vs A Grain-Based Free-Choice Diet, Anlly Miley Fresno Rueda
Characterization Of The Rumen Bacterial Communities Of Bison Heifers Fed A Grass-Based Diet Vs A Grain-Based Free-Choice Diet, Anlly Miley Fresno Rueda
Electronic Theses and Dissertations
A century ago, the North American grasslands and prairie ecosystems were dominated by bison. At least 30 million bison roamed the Great Plains when the first explorers arrived. By 1900, there were little over a thousand bison remained in the United States and Canada. Recovery efforts has been made since the 20th century to reestablish the herds and increase the bison population. Today, over 500,000 bison are distributed across North America, with more than 90% of the existing bison population under commercial production. Modern conservation strategies are made via the collaborative efforts of conservationist, producers, and researchers, resulting in increased …
The Physiology And Evolution Of Selenite Respiration In Bacteria, Michael Wells
The Physiology And Evolution Of Selenite Respiration In Bacteria, Michael Wells
Electronic Theses and Dissertations
The selenium oxyanions selenate (Se(VI)) and selenite (Se(IV)) can be utilized by some bacteria and archaea as terminal electron acceptors in anaerobic respiration. Se(VI) and Se(IV) respiration is mediated by a phylogenetically and ecologically diverse array of organisms, suggesting that selenium respiration is ubiquitous in natural environments. Several respiratory Se(VI) reductases have been characterized in bacteria, revealing that Se(VI) respiration has evolved independently several times in this domain. Se(IV) respiration, in contrast, has yet to be characterized. I have purified and characterized the first respiratory Se(IV) reductase from Bacillus selenitireducens MLS10. The Se(IV) reductase appeared to purify as a single …
Effects Of Warming On Decomposition Of Submerged Plant Litter And Associated Microorganisms In Streamside Channels, Kaity Ackerman
Effects Of Warming On Decomposition Of Submerged Plant Litter And Associated Microorganisms In Streamside Channels, Kaity Ackerman
Electronic Theses and Dissertations
Surface air temperatures are predicted to increase in the near future, which will likely affect microbial activity and carbon flow in stream ecosystems. I performed an experiment in streamside channels at Coweeta Hydrological Laboratory, NC to assess responses of litter-associated microorganisms to moderate increases in water temperature (5 levels, ambient to +4°C). The objectives of the experiment were to determine: (1) if there are differences in the magnitude of responses to temperature among various microbial parameters and (2) whether microbial responses to temperature vary among plant litter of different carbon quality. Thus, I measured litter decomposition rate, fungal biomass (ergosterol), …
Developing Microbial Based Process To Produce High Value Natural Antimicrobial (Glyceollin) In Soybeans And Pullulan From Sucrose, Andrea Zavadil
Developing Microbial Based Process To Produce High Value Natural Antimicrobial (Glyceollin) In Soybeans And Pullulan From Sucrose, Andrea Zavadil
Electronic Theses and Dissertations
Glyceollin is a secondary metabolite produced under stress conditions by soybean to act as a plant defender to pathogen attack. The antimicrobial nature of glyceollin makes it a promising natural alternative to antibiotics if incorporated into livestock feed. However, production of glyceollin is highly variable, dependent on soybean variety, and fungal elicitor used as inoculum. Our study compares two fungal spore elicitors, Trichoderma reesei and Aspergillus sojae on soybeans of diverse maturity level, and fungal susceptibility to determine highest glyceollin titer. Spore inoculation with T. reesei elicited highest glyceollin titers of 2.42±0.20 mg/g at 120 h, while A. sojae elicited …
Investigating Links Between Soil Microbial Structure And Function In Three Major Plant Communities Across Temporal Scales Of Arctic Alaska, Kaj Lynoe
Electronic Theses and Dissertations
Arctic microbial systems continue to get attention today as our understanding regarding their structure and function in a changing system is paramount to C feedbacks with warming and changes in precipitation. Plant communities and microbial community processes across the Arctic landscape are central to understanding tundra ecosystem processes because environmental conditions and plant community structure drive microbial cycling of soil organic matter. Here, we want to understand how soil microbial respiration, mineralization, biomass, and community composition are linked to three Alaskan tundra plant communities, namely Shrub, Tussock, and Sedge tundra and the seasonal variability in this system. A total of …
The Effects Of Constructed Wetlands On Metal Solubilization And Bioavailability In Passive Mine Remediation, Elizabeth Cochran
The Effects Of Constructed Wetlands On Metal Solubilization And Bioavailability In Passive Mine Remediation, Elizabeth Cochran
Electronic Theses and Dissertations
The legacy of coal mining in Appalachia has left many watersheds impacted by abandoned mine drainage. The drainage degrades streams, groundwater and habitats with acidity and toxic heavy metals. The Lowber Passive Remediation System has been in operation since 2004 to remediate high amounts of dissolved Fe, SO4, Al, and Mn. The site consists of six settling ponds and an extensive wetlands at the finish. This study investigated the resolubilization of Fe and Mn in the wetlands and the role of bacteria in resolubilization. During three seasons, field measurements of water quality and lab analysis of Fe, Mn, …
Shrimp Production Environment And The Gut Microbiome: Effects Of Aquaculture Practices And Selective Breeding On The Gut Microbiome Of Pacific Whiteleg Shrimp, Litopenaeus Vannamei, Angela Landsman
Electronic Theses and Dissertations
Knowledge of the functional role of the gut microbiome in animal health and nutrition may provide solutions to shrimp aquaculture challenges, such as improving disease resistance and optimizing growth particularly with low cost feeds. Successful manipulation of bacteria found in the gut requires a deeper understanding of shrimp microbial communities and how their compositional structure is influenced by environmental conditions, and inherent host factors such as genetics. The initial research investigated the intestinal bacterial communities of the Pacific whiteleg shrimp (Litopenaeus vannamei) reared in pond systems compared to indoor aquaculture facilities as an exploration of the effects of aquaculture practices …
Comparing Gut Microbiome And Virome In The Breast Milk- And Formula-Fed Late Preterm Infants, Zyi Wang
Comparing Gut Microbiome And Virome In The Breast Milk- And Formula-Fed Late Preterm Infants, Zyi Wang
Electronic Theses and Dissertations
The neonatal intestinal microbiome consists of all microorganisms in the gut. Although the microbiome is critical to human health and disease, its colonization remains incompletely understood, particularly in the preterm infant. We aimed to characterize the intestinal bacteria microbiome and virome in moderate-to-late preterm infants. We hypothesized that the bacteria microbiome and virome differs between breast milk and formula-fed infants. We collected stool samples from twenty infants born between 32 0/7 and 36 6/7 weeks gestation. Samples were collected after infants reached full volume enteral feedings. Ten infants were breast milk fed and ten received infant formula. DNA and RNA …
Modeling Disease Impact Of Vibrio-Phage Interactions, Christopher Botelho
Modeling Disease Impact Of Vibrio-Phage Interactions, Christopher Botelho
Electronic Theses and Dissertations
Since the work of John Snow, scientists and medical professionals have understood that individuals develop cholera by means of consuming contaminated water. Despite the knowledge of cholera's route of infection, many countries have experienced and still experience endemic cholera. Cholera is caused by the Vibrio cholerae (V. cholerae) bacterium and presents with acute diarrhea and vomiting. If untreated, infected individuals may die due to dehydration. Cholera is a disease that most commonly affects countries with poor infrastructure and water sanitation. Despite efforts to control cholera in such countries, the disease persists. One such example is Haiti which has been experiencing …
Harnessing The Anopheles Microbiome To Conditionally Express Anti-Plasmodial Effectors During The Blood Meal, Jackie Shane
Harnessing The Anopheles Microbiome To Conditionally Express Anti-Plasmodial Effectors During The Blood Meal, Jackie Shane
Electronic Theses and Dissertations
The control of vector-borne diseases such as malaria has been an extremely important research subject for hundreds of years. Because of the complex lifecycles of the pathogens that cause these diseases, finding a comprehensive treatment or preventative strategy has proven extremely difficult. Malaria alone is responsible for almost half a million deaths annually, most of them children under 5 years old. This disease is caused by parasitic protists in the genus Plasmodium that are transmitted to humans from Anopheles sp. mosquitoes. Most preventative strategies that are in use today revolve around controlling the vectors, including bed nets, insecticides, and larval …
Changes In The Microbial Community Of Lubomirskia Baicalensis Affected By Red Sponge Disease, Colin Rorex
Changes In The Microbial Community Of Lubomirskia Baicalensis Affected By Red Sponge Disease, Colin Rorex
Electronic Theses and Dissertations
Lake Baikal is the oldest known lake and a unique ecosystem, home to several species of fresh water sponge. A disease outbreak affecting the dominant species, Lubormirskia baialensis, was recently reported. The cause of the disease has not been determined but one of the current hypothesis is that the increase in methane concentration is correlated to the disease outbreak. This pilot study characterized the microbiomes of sick and healthy sponges through the use of 16S rRNA sequencing. Sick sponge microbiomes shared a conserved group of taxa while the healthy sponge microbiomes had greater diversity. Indicator species analysis identified two significant …
Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett
Range-Wide Prevalence And Impacts Of Pseudocercosporella Inconspicua On Lilium Grayi And An Assessment Of L. Superbum And L. Michauxii As Reservoirs, Cindy L. Barrett
Electronic Theses and Dissertations
Lilium grayi (Gray’s Lily), a southern Appalachian endemic species, is threatened by a Lilium-specific fungal pathogen, Pseudocercosporella inconspicua. The disease is characterized by tan lesions that can cause early senescence, while also lowering seed production and viability. This project tested for P. inconspicua conidia and accessed health at nine locations. The disease was present and ubiquitous across the range of L. grayi. Through identification of P. inconspicua conidia in the field, L. superbum (Turk’s Cap Lily) was identified as an additional host, while L. michauxii (Michaux’s Lily) was disease-free. However, infection was inducible in both species. With …
The Influence Of The Invasive Chinese Tallow (Triadica Sebifera) Leaf Litter On Aquatic Chemistry And Microbial Community Composition, Raymond D. Montez
The Influence Of The Invasive Chinese Tallow (Triadica Sebifera) Leaf Litter On Aquatic Chemistry And Microbial Community Composition, Raymond D. Montez
Electronic Theses and Dissertations
Global climate change and anthropogenic activity have facilitated the movement and invasive potential of nonnative plants in native environments. These invasions can have negative effects on ecosystem diversity and function. The nonnative and invasive plant, Chinese Tallow (Triadica sebifera), has already invaded much of the south eastern US where it is outcompeting native tree species and changing ecosystem diversity in a variety of habitats. Leaf litter from the Chinese tallow has been shown cause changes in dissolved oxygen and pH in the aquatic environment. Turbidity is also affected when Chinese tallow litter is present in water. A series of …
Enhancing The Industrial Potential Of Filamentous Cyanobacteria, Tylor J. Johnson
Enhancing The Industrial Potential Of Filamentous Cyanobacteria, Tylor J. Johnson
Electronic Theses and Dissertations
The objectives of this project were to improve the industrial potential of filamentous N2-fixing cyanobacteria by increasing its biofuel tolerance, and to evaluate the economic feasibility and environmental impacts of a theoretical, cyanobacteria-based biofuel production facility. To develop a method to quantify filamentous cyanobacteria in dilute culture media, a dual-stained fluorescence assay was evaluated. While the viable cell stain (SYTO® 9) was accurate, the non-viable cell stain (propidium iodide) also bound to viable cells. Additional non-viable cell stains were evaluated, but none were accurate at quantifying viability. Thus we concluded that the viable cell stain SYTO® 9 is a reliable …
Diversity Of Free-Living Nitrogen Fixing Bacteria In The Badlands Of South Dakota, Bibha Dahal
Diversity Of Free-Living Nitrogen Fixing Bacteria In The Badlands Of South Dakota, Bibha Dahal
Electronic Theses and Dissertations
Biological Nitrogen Fixation is carried out by a highly diverse group of members of the domains Bacteria and Archaea which express a nitrogenase enzyme complex and are termed diazotrophs. The best known diazotrophs form symbiotic associations with plants, but free-living nitrogen fixing bacteria also contribute a substantial amount of nitrogen to ecosystems, including arid lands. The aim of this study was to isolate free-living diazotrophs from the soil crusts of sod tables of South Dakota Badlands. Samples were obtained from sod tables and the surrounding base (matrix) in spring and fall of 2014. A culture dependent approach was used to …
The Isolation And Characterization Of The Microbial Flora In The Alimentary Canal Of Gromphadorhina Portentosa Based On Rdna Sequences., Amy Renee Robertson
The Isolation And Characterization Of The Microbial Flora In The Alimentary Canal Of Gromphadorhina Portentosa Based On Rdna Sequences., Amy Renee Robertson
Electronic Theses and Dissertations
Multicellular organisms are not single individuals but carry a complex natural microflora with them. This complex's diversity and function can be considered a distinct ecosystem. Traditional methods of isolation and identification miss >90% of the actual diversity. This study uses the gut microflora of the Madagascar hissing roach, Gromphadorhina portentosa, as a model to examine this ecosystem. Isolated cultured bacteria were used to establish methods for identifying members of the microflora based on ribosomal RNA sequences. Universal primers for Eubacterial, Archaeal, and Eukaryotic 16s/18s rRNA were then used for PCR amplification of total DNA isolated from gut contents. Sequences …