Environmental Microbiology and Microbial Ecology Commons^™

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 Role Of The Virb Ligand Ctp In The Molecular Mechanism Of Transcriptional Anti-Silencing In Shigella Flexneri, Taylor M. Gerson, Monika M A Karney, Helen Wing

Life Sciences Faculty Research

In bacteria, nucleoid-structuring proteins bind and constrain DNA, often leading to transcriptional silencing. In Shigella spp., the histone-like nucleoid-structuring protein H-NS silences many genes on the large virulence plasmid. Upon a shift to human body temperature, VirB, a DNA-binding protein and key transcriptional regulator of the Shigella virulence cascade, is produced. VirB counteracts H-NS-mediated transcriptional silencing and belongs to a fast-evolving clade of the ParB superfamily. Like other ParB proteins, VirB binds the ligand CTP. While CTP is essential for the anti-silencing activity of VirB, the role of CTP in the mechanism of VirB-dependent anti-silencing has yet to be …

Microbial Community Structure In Global Soils, Matthew Jabro

CMC Senior Theses

Soil harbors the most diverse microbial communities on Earth, yet whether predictable community types exist across biomes and whether taxonomic composition encodes habitat of origin remain open questions at global scale. This thesis addresses both questions by applying unsupervised clustering and supervised classification to transformed 16S ribosomal RNA (rRNA) amplicon profiles from two independent datasets: the global topsoil survey of Bahram et al. (193 samples) and the Earth Microbiome Project (EMP) soil subset of Thompson et al. (2,209 samples). Application of a sample clustering method based on a mixture of Gaussian Graphical Models (MixGGM) identified 19 clusters in the topsoil …

Regulation And Localization Of Urease In Sporosarcina Pasteurii: Implications For Coastal Protection, Amar Kosovac

UNF Graduate Theses and Dissertations

Coastal erosion is a persistent problem exacerbated by global warming. As the climate changes, the southeastern coast is likely to experience an increased frequency and intensity of storms, which can significantly damage the coastline. The coast is crucial as it serves as a habitat for numerous animals, supports tourism, and underpins infrastructure. Microbially induced calcite precipitation (MICP) is a novel method to enhance erosion resistance in sandy soils using the non-pathogenic bacterium Sporosarcina pasteurii. S. pasteurii produces urease to catalyze urea into bicarbonate, which drives the precipitation of calcium carbonate. Maximal expression of urease is a limiting factor for …

Assessing The Impact Of Storing Water Samples At Ambient Temperature On Plankton Metabarcoding, Stephanie N. Lievano

Honors Undergraduate Theses

Increasing incidence of Harmful Algal Blooms (HABs) has led to fish kills, air quality hazards, and economic impacts. One economic impact is on tourism, one of the main sources of Florida’s income, where billions of dollars are lost to such events. The Florida Fish and Wildlife Conservation Commission Fish and Wildlife Research Institute (FWC-FWRI), with the help of collaborators, collects water samples from across the state for HAB monitoring. These samples are stored at ambient temperature for up to 24 hours which could directly affect data analyses. Here, in collaboration with FWRI-FWC, I investigated whether this storage technique affects plankton …

Phylogenetic Analysis Of Ftsz In Wolbachia: Implications For Host Specificity, Anwar Rovik, Ayu Rahayu

Makara Journal of Science

Wolbachia are the most prevalent and successful endosymbiont in invertebrates and are categorized into 21 supergroups based on genetic phylogeny. The filamenting temperature-sensitive Z (FtsZ) protein is essential for bacterial cell division and is hypothesized to play a role in Wolbachia's control of host reproduction. However, despite FtsZ's importance, little is known about its diversity and function within Wolbachia. This study investigated the variability of the FtsZ-encoding gene among Wolbachia strains and their hosts. FtsZ gene sequences were retrieved from the National Center for Biotechnology Information database, and representative sequences were randomly selected from each host species and analyzed …

Microbial Community And Water Quality Assessment Of Crassostrea Virginica Habitats In Southeast Florida, Stacy Brown

All HCAS Student Capstones, Theses, and Dissertations

Eastern oysters (Crassostrea virginica) are essential habitat-forming species that contribute significantly to coastal water quality due to their filter-feeding behavior. Unlike other coastal regions in the Gulf of Mexico and Northeastern United States, oysters are not commercially managed in Southeast Florida and as a result sparse data exists on locations of the Eastern oyster habitat. Similarly, the benefits of oyster reefs to water quality are also not fully documented in Southeast Florida. Although beneficial and often referred to as keystone habitat building species, populations of C. virginica are not currently listed as protected species so little work has …

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 Source Tracking Protocols For Differentiation Of Fecal Bacteria From Cow, Deer, And Horse, Nika Shams, Michael Beach

Symposium of Student Scholars

Microbial source tracking (MST) attempts to identify specific animal sources of fecal contamination in the environment. While traditional fecal coliform enumeration can give a general measure of contamination, the specificity imparted by modern MST provides a more informative assessment of contaminants and their likelihood to affect human health outcomes.

We have been developing an MST system that detects DNA biomarkers from the gram-negative bacterial genus Bacteroides and the family Lachnospiraceae. They are strict anaerobes found in large quantities in the intestines of animals. Unlike E. coli or Enterococci, host-specific strains of Bacteroides and Lachnospiraceae exist. To this end, we …

Disruption Of The Oswrky71 Transcription Factor Gene Results In Early Rice Seed Germination Under Normal And Cold Stress Conditions, Santiago Bataller, James A. Davis, Lingkun Gu, Sophia Baca, Gaelan Chen, Azeem Majid, Anne J. Villacastin, Dylan Barth, Mira V. Han, Paul J. Rushton, Qingxi J. Shen

Life Sciences Faculty Research

Background

Early seed germination in crops can confer a competitive advantage against weeds and reduce the time to maturation and harvest. WRKY transcription factors regulate many aspects of plant development including seed dormancy and germination. Both positive and negative regulators of seed germination have been reported in many plants such as rice and Arabidopsis. Using a transient expression system, we previously demonstrated that OsWRKY71 is a negative regulator of gibberellin (GA) signaling in aleurone cells and likely forms a “repressosome” complex with other transcriptional repressors. Hence, it has the potential to impact seed germination properties.

Results

In this study, we …

Effects Of Microplastic Biofilms On An Anthropogenically Impacted Suburban Lake, Paris M. Velasquez

Masters Theses

Plastics have been observed in every location on the planet, and their prevalence in the environment is due in part to their strong resistance to degradation. Inland lakes are susceptible to plastic pollution by highway runoff, which contains plastic fragments of brake pads, car tires, litter, and road paint. These plastics eventually enter freshwater environments and degrade into microplastics (

Onsite Microbial Analyses In One Of The Most Remote Quartzite Subterranean Environment On Earth: Imawarì Yeuta On Venezuelan Tepuis, Martina Cappelletti

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

Antarctic Glacier Melting Modeling Distribution Of Bacterial Community Structure, Corina Itcus, Constantin Marin, Soon Gyu Hong, Manuela Elisabeta Sidoroff, Cristian Coman, Cristina Purcarea

FRONTIERS UNBOUND: Exploring Extreme Environments

No abstract provided.

Optimizing The Expression Of Polyethylene Terephtalate Hydrolase-Encoding Synthetic Gene In Escherichia Coli Arctic Express (De3), Jocelyn Nataniel, Maria Ulfah, Dini Achnafani, Niknik Nurhayati, Gabriela Christy Sabbathini, Sri Rezeki Wulandari, Abinawanto Abinawanto, Is Helianti

Makara Journal of Science

The waste of polyethylene terephthalate (PET) plastic waste in Indonesia is a pressing concern due to its slow degradation and potential environmental damage. One promising solution is to utilize polyethylene terephthalate hydrolase from Ideonella sakaiensis (IsPETase), an enzyme that specifically degrades PET. However, inducing the expression of IsPETase synthetic gene in Escherichia coli BL21 (DE3) has been challenging because much of it remains insoluble. This study aimed to express IsPETase in E. coli Arctic Express (DE3) and optimize the conditions to enhance its production. First, pET22b(+)pelB-IsPETase was inserted into E. coli Arctic Express (DE3). The …

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 …

Rainwater Harvesting Systems Metagenomics, Jade Riddle, Julia Parsons

Spring Showcase for Research and Creative Inquiry

Climate change induced water scarcity has led to an increasing interest in non-traditional water sources such as rainwater. However, there are lingering health and safety concerns due to the lack of research into the microbial communities contained within collection systems. To address this gap, water samples were collected from rain barrels around northern Virginia for microbial analysis. Each microbe within the sample has a unique genome subject to DNA testing. Environmental DNA was prepared from the collected water samples. To characterize the microbial community, both targeted sequencing and whole genome sequencing approaches were used. Using targeted sequencing of the 16s …

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 …

Long-Term Impacts Of Conservation Pasture Management In Manuresheds On System-Level Microbiome And Antibiotic Resistance Genes, Mitiku Mihiret Seyoum, Amanda Ashworth, Kristina M. Feye, Steven C. Ricke, Phillip R. Owens, Philip A. Moore Jr., Mary Savin

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Animal manure improves soil fertility and organic carbon, but long-term deposition may contribute to antibiotic resistance genes (ARGs) entering the soil-water environment. Additionally, long-term impacts of applying animal manure to soil on the soil-water microbiome, a crucial factor in soil health and fertility, are not well understood. The aim of this study is to assess: (1) impacts of long-term conservation practices on the distribution of ARGs and microbial dynamics in soil, and runoff; and (2) associations between bacterial taxa, heavy metals, soil health indicators, and ARGs in manures, soils, and surface runoff in a study following 15 years of continuous …

Sensing The Rhizosphere: Microbial Transcriptome Responses To Root Exudates And Redox-Active Metabolites, Ankita Bhattacharyya

Dissertations

The term “rhizosphere” describes the dynamic interface between plant roots and soil influenced by root exudates. It is a hotspot of microbial activity, plant-microbe, and microbe-microbe interactions. Distinct variations in bacterial diversity are thought to be driven by plant root exudates. However, the molecular details of these processes still remain unclear.

I addressed this gap by focusing on two strains, Pseudomonas synxantha 2-79 and Burkholderia lata 383, representing diverse groups of Gammaproteobacteria comprised of species with environmental, agricultural, and medical significance. In the first part of this project, we used a combination of metabolomics and RNA-seq to characterize transcriptome responses …

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 …

The Response Of Microcystis And The Microbiome To Exogenous Hydrogen Peroxide, Bryan A. Puma

Masters Theses, 2020-current

Microcystis spp. produce prolific annual blooms in freshwater systems worldwide. The success of these blooms depends heavily on the Microcystis spp. overcoming environmental factors such as oxidative stress caused by reactive oxygen species (ROS) like hydrogen peroxide. Most Microcystis genomes do not contain many genes for responding to oxidative stress, including those that encode the enzyme catalase. Other cyanobacteria such as Prochlorococcus that also lack hydrogen peroxide degrading enzymes have been shown to benefit from partnerships with heterotrophic bacteria. Microcystis spp. may also receive similar benefits from heterotrophic bacteria in the phycosphere. To test this hypothesis, we examined the …

Gene Expression Changes Linked To Phenylpropanoid-Based Resistance To Fusarium Head Blight Of Wheat, Shiv Singla

Department of Plant Pathology: Dissertations, Theses, and Student Research

Fusarium graminearum is a devastating pathogen of wheat that causes Fusarium head blight (FHB) and contaminates the grain with the mycotoxin deoxynivalenol (DON). Resistance to FHB is quantitative and it is important to identify additional genes conferring resistance against it. The goal of this thesis was to examine if the constitutive expression of two sorghum phenylpropanoid pathway genes, SbCCoAOMT (encoding caffeoyl-CoA O-methyltransferase) and SbC3’H (encoding p-coumarate 3-hydroxylase), in the moderately-susceptible spring wheat CB037 can provide Type-I and Type-II resistance to F. graminearum and determine the underlying mechanisms of the enhanced resistance. The constitutive expression lines (CCoAOMT413, CCoAOMT421, C3H112, …

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 …

Host-Microbe Interactions In Non-Native Estuarine Anemones: Biogeography And Temperature, Parker K. Lund

Cal Poly Humboldt theses and projects

Non-native species are increasing in prevalence around the world, resulting in negative economic and ecological impacts. However, the broad distributions of non-native species also offer a system for investigating the response of host-associated microbial communities to environmental factors across a range of ecological scales. At the broadest scale, I investigated the geography of microbial communities in the non-native estuarine anemone Diadumene lineata on the west coast of the United States of America. Across latitudes, microbial community composition was very similar and displayed a high percentage of Klebsiella spp. at all sites. However, the communities in California tended to exhibit higher …

Extension Of The Ergot Alkaloid Gene Cluster, Samantha Joy Fabian

Graduate Theses, Dissertations, and Problem Reports (ETD)

Specialized metabolites produced by fungi impact human health. A large portion of the pharmaceuticals currently on the market are derived from metabolites biosynthesized by microbes. Ergot alkaloids are a class of fungal metabolites that are important in the interactions of environmental fungi with insects and mammals and also are used in the production of pharmaceuticals. In animals, ergot alkaloids can act as partial agonists or antagonists at receptors for 5-hydroxytryptamine (serotonin), dopamine, and noradrenaline as ergot alkaloids have chemical structures similar to those neurotransmitters. Therefore, they affect insects and mammals that consume them and can be used to produce drugs …

Fine-Scale Genetic Structure In Rhizosphere Microbial Communities Associated With Chamaecrista Fasciculata (Fabaceae), Mahboubeh Hosseinalizadeh Nobarinezhad, Lisa E. Wallace

Biological Sciences Faculty Publications

Soil microbiota of the rhizosphere are an important extension of the plant phenotype because they impact the health and fitness of host plants. The composition of these communities is expected to differ among host plants due to influence by host genotype. Given that many plant populations exhibit fine-scale genetic structure (SGS), associated microbial communities may also exhibit SGS. In this study, we tested this hypothesis using Chamaecrista fasciculata, a legume species that has previously been determined to have significant SGS. We collected genetic data from prokaryotic and fungal rhizosphere communities in association with 70 plants in an area of …

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 …

Microbial Dimension Of Symbiosis And Dysbiosis In Fungus–Gardening Ants, Blake S. Bringhurst

Biology Theses

With symbiotic partners, the means by which a host obtain a symbiont influence the specificity between the host and the symbiont. One such system where symbiont specificity is seen to varying degrees is with higher attine ants. Higher attine ants have symbiotic relationships with the fungal cultivar they grow and the bacterial symbionts in their microbiomes. Among the higher attines, there are two broad groups of fungi. Most ants in the genus Trachymyrmex tend to grow Clade–B fungi, which are a group of undescribed Leucocoprinus species, while leaf–cutting ants in the genera Acromyrmex and Atta tend to grow Clade–A fungi …