Environmental Microbiology and Microbial Ecology Commons^™

Discovery Of Bmi-Associated Gut Microbiome Signatures In The Awi-Gen 2 Cohort, Meriem Yagoubi

Theses and Dissertations

Obesity is increasing across sub-Saharan Africa amid rapid dietary, environmental, and urbanization transitions, yet the gut microbiome features associated with adiposity in African populations remain under-characterized. This study investigated whether species-level gut microbiome composition is associated with body mass index (BMI) in the AWI-Gen 2 cohort, and whether BMI-associated microbial signals remain detectable after accounting for the dominant geographic structure of the microbiome. Gut microbiome community structure and diversity were characterized across 1,665 participants, and differential abundance analysis was used to identify taxa associated with BMI after controlling for study site. Machine learning models were then trained to assess how …

Geographical And Anatomical Microbiome Variation In Invasive Green Iguanas (Iguana Iguana), Amanda A. Diaz

All HCAS Student Capstones, Theses, and Dissertations

The common green iguana (Iguana iguana) was introduced to South Florida in 1965 and has since been an especially pernicious threat both environmentally and economically. This highly invasive species is also expanding in range and populations at an astonishing rate. Understanding how this reptile is able to adapt and thrive in novel environments is of imperative need in order to begin managing their disruptive populations. Notwithstanding their negative impacts and significance, the microbiome of wild populations has not yet been characterized. Here, using 16S ribosomal RNA gene sequencing, this study is the first to characterize the microbiome composition …

Combining Crispr And Nanoasv To Uncover The Rare Bacterial Communities Of The Human Oral Microbiome, Gilma Ruth Sevilla Alvarez

Master's Projects

Studying the oral microbiome is vital because its health implications are not contained to the mouth. Cariogenic bacteria cause tooth demineralization and oral microbes that translocate to extra-oral organ systems are linked to conditions like Alzheimer’s disease, heart disease, diabetes, and cancer. Some of these pathogens belong to the most abundant phyla in the oral cavity: Bacillota, Pseudomonadota, Bacteroidota, Actinomycetota, Spirochaetota, and Fusobacteriota, which together comprise 94% of the oral microbiome. This project uses CRISPR-Cas9 to deplete sequences from highly abundant phyla and the Eubacteria domain, enriching the remaining 6% of rarer taxa. Paired with NanoASV for single-nucleotide resolution, this …

Effects Of Fermented Soybean Products On The Human Gut Microbiome, Microbial Metabolism, And Host Physiology, Shannon Moncier

Biology Dissertations

Fermented soybean products (FSPs) contain soybean-derived substrates, fermentation-associated microorganisms, and bioactive compounds that may interact with the human gut microbiome and host physiology. However, despite the growing interest in FSPs, longitudinal human studies specifically evaluating traditional Korean-FSPs (K-FSPs), particularly among United States-based populations, remain limited. The objective of this work was to evaluate the effects of three K-FSPs, including Cheonggukjang, Gochujang, and Doenjang, on host physiological responses, gut microbial community structure, predicted microbial functional potential, and fecal butyrate responses in healthy adults. Three independent dietary intervention cohorts were conducted using FSP formulations produced either by traditional artisan methods (Product A) …

Exploring The Application Of Wastewater Monitoring To Determine The Prevalence And Diversity Of Influenza On The Campus Of West Virginia University, Lakyn Renee Sanders

Graduate Theses, Dissertations, and Problem Reports (ETD)

Influenza viruses (IV) affect populations globally, with the World Health Organization (WHO) estimating that IV are responsible for an estimated 3-5 million infections and 290,000 – 650,000 deaths annually^1–3. More specifically, the 2019-2020 IV season is associated with an estimated 38 million illnesses and 22,000 deaths in the United States alone⁴. IV are rapidly spread between individuals through direct contact with infected individuals, contaminated surfaces, or aerosolized virus particles². Traditional IV infection monitoring relies on clinical screening of patients presenting influenza-like symptoms, commonly through the use of multi-target panel tests such as the BioFire …

Exploring The Interplay Of Operational Conditions, Microbial Communities, And Water Quality In Drinking Water Ozone-Biofiltration, Kara Yvonne Cunningham

Graduate Theses, Dissertations, and Problem Reports (ETD)

Ensuring reliable access to safe drinking water is a growing global challenge as water utilities face variable source water quality driven by population growth, land‑use change, and climate change impacts. To address these challenges, utilities are implementing advanced treatment technologies designed to improve reliability under variable source water conditions. Ozone-biofiltration has emerged as a treatment approach that can reduce a wide range of natural and anthropogenic contaminants. However, despite its increased use, there is limited insight into the biological processes shaping filter function or how they respond to operational and environmental changes. Advances in molecular microbiology and high-throughput sequencing now …

Microbial Guardians Of The Savannah: Unraveling The Gut Microbiome For African Carnivore Conservation, Laura E. Peirson

All NMU Master's Theses

Non-invasive fecal sampling is essential for wildlife gut microbiome (GMB) research, yet field conditions often limit preservation options. I compared gut bacterial communities in paired fecal samples preserved in stabilization tubes and air-dried in paper bags collected from anesthetized African lions (Panthera leo) and spotted hyenas (Crocuta crocuta) in Etosha National Park, Namibia. Additional opportunistic samples from carnivore kill sites were also analyzed. No significant differences in alpha or beta diversity were detected between preserved and dried samples, although bacterial beta diversity differed between preserved and opportunistic samples (PERMANOVA). Core bacterial communities remained consistent across sample …

Distribution, Roles And Environmental Drivers Of Bacterial Communities In The Chesapeake And Delaware Bays, Mir Alvee Ahmed

All Dissertations

In this dissertation, water samples from the Chesapeake and Delaware Bay estuaries were analyzed to see how estuarine environmental gradients drive distributions, functional potential, growth estimates and gene expressions of bacteria. To answer this, the abundant and versatile taxa– Rhodobacterales and Actinobacteriota, along with broader particle-attached (PA) vs. free-living (FL) bacterial assemblages of these Bays were analyzed using a multifaceted ‘omics approach.

The PA fraction, differing from the FL in taxonomy, distribution, functional potential and estimated growth rates across salinities, and bays harbored genes degrading complex aggregates, and surface attachment. The FL counterpart presented genes involved in nutrient uptake …

Crayfish Microhabitats Provide A Close Association With Benthic Microbiomes To Support Cleaning Symbionts., Kyle J. Harris, John Hoverson, Matthew Becker, Matthew M. Cooke Mr

NEXUS: The Liberty Journal of Interdisciplinary Studies

Stream ecosystems promote variable microhabitats along a longitudinal gradient. These microhabitats support dynamic biotic assemblages. One such microhabitat in freshwater streams involves the external surface of crayfish. We investigated the microbiome of crayfish exoskeletons and the surrounding environment (water and substrate) in association with the presence and abundance of crayfish cleaning ectosymbionts (branchiobdellidans). These ectosymbionts actively consume the biofilm on crayfish as they live and reproduce in association with crayfish microhabitats. Sequenced microbes of the environment and crayfish were compared for dominant taxa. While the sample types (water, substrate, and crayfish) had significantly different microbiomes, there was not a significant …

Microbial Biodiversity Of The James River Rock Pool Ecosystem., Jordan C. Heydt

Masters Theses, 2020-current

Rock pools are ephemeral aquatic environments that offer a unique opportunity to study complex communities and their responses to environmental changes. The urban James River rock pool system consists of over 700 individual rock pools varying in size and depth. This unique urban freshwater ecosystem has been studied for its invertebrate, plant, and zooplankton populations but not for its microbial community composition. To fill that gap, the microbial community of this system was characterized using 16S rRNA gene sequencing, and the influence of environmental variables on the community composition was analyzed. Our findings show variation in microbial community composition across …

Life After Death: Investigating The Resistance And Recovery Of Fungal Communities To Foundation Tree Mortality, Jessie F. Marlenee

Biology ETDs

Tree mortality can have cascading effects on the composition and resilience of interacting fungal communities. Yet, little is known about the impact tree mortality, distinct from abiotic drivers (i.e., drought), has on these communities. This dissertation focuses on the resilience of fungal communities to experimental tree mortality in a piñon-juniper woodland. In chapter one, I found that piñon mortality reduced piñon fine root biomass and piñon mycorrhizal fungal diversity, whereas juniper mycorrhizal fungi were unaffected by juniper mortality. In chapter two, I revealed that piñon mortality altered the composition and spatial structure of mycorrhizal and saprotrophic fungi in the soil, …

Microbial Hydrocarbon Degradation And Carbon Cycling In Marine And Freshwater Sediments: A Comparative Metagenomic Analysis, Yogita M. Warkhade

Dissertations, Master's Theses and Master's Reports

Microbes are essential in keeping our environment balanced, especially by fixing carbon dioxide and breaking down hydrocarbons in aquatic sediments. This thesis explores how microbial communities perform these tasks in different sediment environments, including marine areas (Caspian Sea and Mediterranean Sea) and freshwater ecosystems (Great Lakes). The first part of this thesis reviews current knowledge about how microbes degrade hydrocarbons. It highlights the importance of different pathways microbes use depending on oxygen availability. The second part provides a detailed study of the microbial communities found in marine sediments from the Caspian Sea and Mediterranean Sea, showing that microbes in these …

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 …

First Biogeochemical Study Of Mira De Aire Cave: The Biggest Karstic System In Portugal, Alba Gómez-Arias, Julio Castillo, Nicasio Tomás Jiménez-Morillo, Beatriz Cubero, Sara Gutiérrez-Patricio, Pedro N. Jimenez-Morillo, José A. Gonzalez-Perez, José M. De La Rosa, Ana Z. Miller

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

Investigation Of The Microbiome Of A Recirculating Aquaculture System (Ras) For Crassostrea Virginica Larvae, Isabelle Townsend

Master's Theses

Recirculating Aquaculture Systems (RAS) offer control over physicochemical and biological factors impacting aquaculture success. One understudied facet of RASs is the water microbiome. Oyster larval microbiomes are shaped by their aquatic microbiomes. Understanding the dynamics of and the factors shaping RAS microbiome may provide insights to how the microbiome can be a tool for optimizing larval production. This study’s goals were to investigate the microbiome stability of a RAS rearing oyster larvae across time and space, determine impacts of larval presence on the microbiome, and examine connections between larvae production outcomes and microbiome stability. Water samples were collected weekly from …

Metagenomic Analysis Of Antarctic Microbial Communities, David Michael Robinson

Biology ETDs

The research presented in this dissertation focuses on microbial roles in biogeochemical cycling in Antarctic aquatic environments. The major objective of my research was to examine the impact of biotic and abiotic pressures on nutrient cycling in microbially dominated systems. I used three perennially ice covered lakes in the McMurdo Dry Valleys (MDVs) along with subglacial lakes Whillans and Mercer as natural case studies. The MDVs are located in Victoria Land, East Antarctica and have been studied since 1993 as part of the McMurdo Long Term Ecological Research Project. Viruses in the MDVs were shown to be seasonally abundant and …

Establishment Of Bacteroides In The Gut And Its Role In The Cystic Fibrosis Gut-Lung Axis, Rebecca A. Valls

Dartmouth College Ph.D Dissertations

In the quest to understand the complex interplay between the gut microbiota and cystic fibrosis (CF), a disease characterized by chronic upper respiratory complications and an exacerbated proinflammatory response, our lab engaged in a collaborative study with Dartmouth-Hitchcock Medical Center (DHMC) to characterize the gut microbiota of pediatric CF patients. Initial analyses established a connection between gut microbial composition and respiratory health, particularly highlighting a scarcity of Bacteroides species compared to healthy controls. In following investigations, we utilized random forest models to understand how stool microbiota may influence clinical outcomes of these pediatric CF patients, including: age, upper respiratory infections, …

Archaeal Diversity In The Anna's Hummingbird Microbiome, Lauren E. Chance

Honors Scholar Theses

The microbial communities that are present in and on vertebrates are collectively called the microbiome. The composition of a microbiome is dependent upon the host, the environment, and evolution. There has been extensive research on the bacterial composition of host-associated microbiomes, however, there has been much less work on the archaeal composition of host-associated microbiomes. Archaea have previously been assumed to primarily exist in extreme environments, but this may not be true and has been influenced by their generally low abundance and methodological difficulties in detection. It is possible they are consistent members of diverse host-associated microbiomes.

Archaea-specific PCR primers …

Using Single Cell Genomics To Explore The Impact Of Marine Viruses On Microbial Respiration., Paxton Tomko

MCB Articles

Viral metabolic reprograming of marine prokaryotes, through the use of virally encoded auxiliary metabolic genes (AMGs), plays a critical role in marine ecosystem function by influencing biochemical cycles and genetic diversity in these environments. Despite the fundamental role viruses play in global environmental ecosystems, they remain an understudied aspect of microbial ecology and evolution, in part due to the methods available for studying virus host interactions in natural systems. Thus far, metagenomic analyses have been used to study the interactions of virus host pairs, but these types of analyses have their limitations in accurately linking viruses to hosts, or culture-based …

Role Of Extracytoplasmic Function (Ecf) Sigma Factors In The Survival And Symbiosis Of Nitrogen-Fixing Bradyrhizobium Under Desiccation Stress And Comparative Analysis Of Desiccation-Tolerant Rhizobial Isolates, Mohammad Kamruzzaman

Biology Dissertations - Archive

Rhizobia are soil bacteria that facilitate biological nitrogen fixation (BNF) through a symbiotic relationship with legumes such as soybeans. As an eco-friendly alternative to chemical nitrogen fertilizers, rhizobial inoculants can enhance plant growth and yield. However, they face various stresses, including drought (i.e., desiccation). Rhizobia can manage desiccation stress by accumulating trehalose, a disaccharide produced by genes such as otsA, otsB, and treS. Extracytoplasmic function (ECF) sigma factors sense external signals and regulate these desiccation-related genes during the stress. Previous studies have highlighted the importance of EcfG in response to desiccation stress and symbiosis. Based on the protein sequence …

Reducing Food Scarcity: The Benefits Of Urban Farming, S.A. Claudell, Emilio Mejia

Journal of Nonprofit Innovation

Urban farming can enhance the lives of communities and help reduce food scarcity. This paper presents a conceptual prototype of an efficient urban farming community that can be scaled for a single apartment building or an entire community across all global geoeconomics regions, including densely populated cities and rural, developing towns and communities. When deployed in coordination with smart crop choices, local farm support, and efficient transportation then the result isn’t just sustainability, but also increasing fresh produce accessibility, optimizing nutritional value, eliminating the use of ‘forever chemicals’, reducing transportation costs, and fostering global environmental benefits.

Imagine Doris, who is …

Tracing Evolution Of Gene Transfer Agents Using Comparative Genomics, Roman Kogay

Dartmouth College Ph.D Dissertations

The accumulating evidence suggest that viruses and their components can be domesticated by their hosts, equipping them with convenient molecular toolkits for various functions. One of such domesticated system is Gene Transfer Agents (GTAs) that are produced by some bacteria and archaea. GTAs morphologically resemble small phage-like particles and contain random fragments of their host genome. They are produced only by a small fraction of the microbial population and are released through a lysis of the host cell. Bioinformatic analyses suggest that GTAs are especially abundant in the taxonomic class of Alphaproteobacteria, where they are vertically inherited and evolve …

Mechanistic Examination Of Protist-Mediated Plant Growth Through The Comparative Development Of Medicago Truncatula, Shane Connolly

University Scholar Projects

Protists are known to increase plant growth through two main mechanisms: the microbial loop and the alteration of the root microbiome. The microbial loop is a nutrient recycling method in which protists provide inorganic nitrogen ions to the plant. Alteration of root microbiome leads to the removal of plant pathogens and shifting communities towards plant growth-promoting bacteria (PGPB). This study aimed to elicit which mechanism could produce the largest boost in shoot weight for Medicago truncatula. A series of microcosm experiments were explored in which M. truncatula was grown with variable microbiome structures to allow for mechanism differentiation. The …

Comparative Analysis Of Rhizosphere And Endosphere Microbiome Of Different Blueberry Species (Vaccinium Sp.), Niladri Bhowmik

Master's Theses

Blueberries are an important agricultural commodity in all over the United States. Due to its health benefits, there is a huge demand globally, thus expanding the industry. Breeding programs are essential to maintain such industries. Challenges that play a role in contemporary breeding programs are various biotic and abiotic stress factors. Studies have shown that microorganisms are recruited by plants to alleviate them during stressful conditions. Though blueberries have been cultivated for about 100 years, how the microbiome has been affected due to this is poorly understood. We hypothesized that interspecific crosses and artificial selection have significantly changed the microbiome …

Effects Of Cyanobacteria Harmful Algal Blooms On The Microbial Community Within Lake Okeechobee, Fl, Usa, Paisley S. Samuel

All HCAS Student Capstones, Theses, and Dissertations

The Lake Okeechobee (Lake O) watershed is a Floridian freshwater ecosystem that has been affected by the increased frequency and intensity of harmful cyanobacterial bloom (cyanoHAB) events occurring over recent decades. Lake O has several ecological and economic purposes such as providing habitats for various organisms and providing drinking water to urban communities surrounding the lake. Toxic cyanoHAB events are posing a threat to the ecosystem and economy of the lake due to the degradation of water quality. This study investigates how the microbial community structure within Lake O is affected by annual cyanobacterial harmful algal blooms over several years …

Identification Of Novel Biosynthetic Gene Clusters Encoding For Polyketide/Nrps-Producing Chemotherapeutic Compounds From Marine-Derived Streptomyces Hygroscopicus From A Marine Sanctuary, Hannah Ruth Flaherty

Honors Theses and Capstones

Nearly one out of six deaths in 2020, around ten million people, were caused by cancer, making it a leading cause of death worldwide (WHO, 2022). This major public health issue, in addition to the rise of multidrug-resistant (MDR) pathogens, provides a high demand for the discovery of new pharmaceutical drugs to be used clinically to treat these conditions. The Streptomyces genus accounts to produce 39% of all microbial metabolites currently approved for human health, indicating its potential as an important species to study for antimicrobial and anticancer agents. The long linear genome of Streptomyces contains specialized sequences known as …

Microbial Communities In The Guana Tolomato Matanzas National Estuarine Research Reserve: An Assessment Of The Responses Of Spartina Alterniflora Epiphytes To Nitrogen Enrichment, And A Characterization Of Benthic Cyanobacterial Diversity, Anne C. Hurley

UNF Graduate Theses and Dissertations

Elevated nitrogen and phosphorus inputs from anthropogenic sources, which can lead to significant increases in algal biomass and changes in algal community composition, poses a serious threat to estuarine ecosystems worldwide. While numerous studies have addressed the impacts of nutrient enrichment on epiphytic algae in seagrass habitats, few have investigated potential nutrient-driven changes to epiphytes on emergent salt marsh plants, such as Spartina alterniflora. Epiphytic microalgae on S. alterniflora play an important role in food availability in salt marsh ecosystems, and epiphytic nitrogen-fixing cyanobacteria also provide an important source of nitrogen for salt marsh consumers. The first study included …

Analysis Of Geographic Variability Of Fecal Microbiomes Of Fratercula Arctica And Cross-Comparison Of Fecal Microbiomes Of Different Avian Feeding Types, Eric Jose Ramon Martinez

LSU Master's Theses

Gastrointestinal (gut) microbiota have a multitude of effects on their host, from aiding in digestion, to facilitating nutrient uptake, detoxification, and interactions with the immune system. Multiple factors have been identified that influence the composition of vertebrate microbiomes; these include host genetics, environmental conditions, diet and age, sex, and geography. However, broad inferences about wild avian gut microbial diversity and function under natural conditions are limited. Most knowledge on avian microbiomes is derived from studies on domestic poultry. Information on non-model taxa may provide important contextual information about vertebrate host-microbiome interactions and aid in future management of vulnerable species. Here, …

Evaluating Soil Health Changes Following Cover Crop And No-Till Integration Into A Soybean (Glycine Max) Cropping System In The Mississippi Alluvial Valley, Alexandra Gwin Firth

Theses and Dissertations

The transition of natural landscapes to intensive agricultural uses has resulted in severe loss of soil organic carbon (SOC), increased CO₂ emissions, river depletion, and groundwater overdraft. Despite negative documented effects of agricultural land use (i.e., soil erosion, nutrient runoff) on critical natural resources (i.e., water, soil), food production must increase to meet the demands of a rising human population. Given the environmental and agricultural productivity concerns of intensely managed soils, it is critical to implement conservation practices that mitigate the negative effects of crop production and enhance environmental integrity. In the Mississippi Alluvial Valley (MAV) region of Mississippi, USA, …

Comparative Transcriptomic Study Between Cyanobacteria That Contain Chlorophyll D And Those That Lack Chlorophyll D, Fernanda Montoya

Honors Capstones

All cyanobacteria, which perform oxygenic photosynthesis on Earth, contain the photosynthetic pigment chlorophyll a (Chl a) that absorbs light in the violet and red region of the visible spectrum. Cyanobacteria of the Acaryochloris species, however, contain the rare photosynthetic pigment chlorophyll d (Chl d) that absorbs light in the far-red region. Chl d’s ability to absorb light in this region allows it to avoid competing with other photosynthetic organisms for light. Creating a photosystem that uses Chl d in plants would be of great use for agricultural land optimization, but requires knowledge of the biosynthetic pathways of …