Microbiology Commons^™

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 …

Quantifying Amendment Impact On Microbial Respiration Rate, Qwynn Starrwalker

Honors Undergraduate Theses

Wetlands play a critical role in the global carbon cycle by acting as carbon sinks, where the flooded anaerobic conditions cause slow microbial respiration compared to other soils. Comparatively more carbon is stored in the soil as organic matter than is released as carbon dioxide (CO₂). Making wetland pools of soil organic matter less available to microbes for respiration could reduce overall atmospheric CO₂ and slow global warming. This study examined the effect of kaolinite, goethite, and lime on microbial respiration rates in wetland soils under alternating hydrologic conditions. Homogenized soil from a cypress dome was separated …

Population Genomics And Evolution Of Pseudomonas Aeruginosa, Samara T. Choudhury

Electronic Theses & Dissertations (2024 - present)

Pseudomonas aeruginosa is a Gram-negative bacterium ubiquitous in diverse environments and an opportunistic pathogen in humans. It is a leading cause of chronic lung infections in cystic fibrosis patients and of hospital-acquired pneumonia and sepsis. With a large flexible genome and abundant mobile genetic elements, P. aeruginosa exhibits high levels of antimicrobial resistance (AMR), making it a significant public health threat. Evolutionary processes such as homologous recombination, and horizontal gene transfer generate extensive genomic diversity in this species and facilitate the spread of resistance genes. In this dissertation, I investigate the genetic and evolutionary factors shaping P. aeruginosa population structure …

Regional Oceanographic Controls On Water Column Nitrogen Fixation In Northern Australian Waters, Douglas G. Capone, Ajit Subramaniam, Yubin Raut, Joseph P. Montoya, Margaret R. Mulholland, Rachel Ann Foster, Miles Furnas, Edward J. Carpenter

OES Faculty Publications

Large blooms of the diazotrophic cyanobacteria, Trichodesmium, have been re-ported along the north coast of Australia and are readily evident in remote sensing images. During a research cruise in November 1999, we sampled from Townsville to Broome, examined Trichodesmium population densities and their rates of carbon and N₂ fixation alongside microscopy-based cell counts of them and other cyanobacte-rial diazotrophs. Additionally, we also enumerated the picophytoplankton community using flow-cytometry, measured bulk chlorophyll concentrations, carbon and N₂ fixation rates, and water column hydrography, enabling comparison of diazotrophic and picophytoplankton functional groups across the system. Agglomerative hierarchical clustering analysis of physicochemical oceanographic …

Investigating The Anti-Apoptotic Properties Of The N-Terminus Of The Chlamydia Trachomatis Effector Tarp, Kasey S. Jordan

Graduate Studies Theses and Dissertations 2026

As the most prevalent bacterial STI in the United States and leading cause of infection-related blindness worldwide, the obligate intracellular bacteria, Chlamydia trachomatis (Ct), poses a significant threat to public health. As an obligate intracellular bacteria, invasion of the host cell is a crucial step in Chlamydia’s developmental cycle. To drive invasion, Ct injects prepackaged effectors into the host cell using a T3SS. An early Chlamydial effector, translocated actin recruiting phosphoprotein, or Tarp, interacts with host cell actin to promote invasion, mediated via Tarp’s C-terminal region. Although the function of Tarp’s C-terminus is well defined, the Tarp’s N-terminus …

The Importance Of The Proline Residue In The Ldiapa Motif Of Cholera Toxin, Akash Bharathan

Honors Undergraduate Theses

Cholera is currently on its seventh global pandemic, disproportionately affecting developing countries. Vibrio cholerae, the bacterial etiologic agent, is able to cause infection by adhering to intestinal epithelial cells and secreting cholera toxin (CT), an AB-type exotoxin that dysregulates signaling pathways. Previous research by the Teter lab has shown that Hsp90, a host cytosolic chaperone, is required for CT to enter the cytosol where it produces toxic effects. Hsp90 binds to CT at two specific motifs, RPPDEI and LDIAPA. The prolines in the RPPDEI motif are essential for binding, but the proline in the LDIAPA has yet to be …

Targeted And Screening Based Approaches To Analyze Drm Transcriptional Repressor Complex Activity In Caenorhabditis Elegans, Emily Washeleski

Dissertations, Master's Theses and Master's Reports

The molecular machinery that control the eukaryotic cell cycle, specifically the processes that mediate the switch between cellular division or quiescence, are essential for cellular and organismal viability. However, how the same machinery integrates with developmental or differentiation programs is less well understood. In Caenorhabditis elegans, the 8-subunit DRM complex (for Dp, Rb and MuvB), whose subunits belong to the Synthetic Mulitivulva (SynMuv) B class genes, is a central regulator of the cell cycle but also prevents inappropriate cell fate specification. The conserved mammalian DREAM complex (for Dp, Rb, E2F, And MuvB) is best known as a transcriptional repressor …

Development Of Shigella Flexneri Detection Method By Real-Time Polymerase Chain Reaction Targeting The Sfmd Gene, Muktiningsih Nurjayadi, Puan Aqila Azizah, Agus Setiawan, Ananda Indah Putri Sihombing, Anisa Fitriyanti, Grace Grace, Gusti Angieta Putri, Helzi Angelina, Royna Rahma Musie, Jefferson Lynford Declan, Gladys Indira Putri, Dandy Akbar Juliansyah, Siti Fatimah, Tiara Fahriza, Irma Ratna Kartika, Fera Kurniadewi, Novitasari Novitasari, Bassam Abomoelak, Hesham Ali El Enshasy, Shyi-Tien Chen

Makara Journal of Science

Shigella flexneri can cause shigellosis, which results in high fever, vomiting, diarrhea, or death. This study developed a detection method based on real-time polymerase chain reaction that targets the sfmD gene of S. flexneri given that the virulence factor encoded by this gene is thought to facilitate adhesion to a host surface. The proposed method involves primer design, DNA isolation, the optimization of primer annealing temperature, and confirmation, specificity, and sensitivity tests. A sfmD primer with an amplicon length of 155 bp was annealed to the target DNA at an optimized temperature of 60 ℃ (range 54 °C–62 °C). This …

Seroprevalence And Risk Determinants Of Toxoplasma Gondii Infection In Pregnant Women In Pakistan: A Cross-Sectional Study, Tajul Haram, Kamran Khan

Journal of Bioresource Management

Toxoplasma gondii is a globally important zoonotic parasite, and maternal infection during pregnancy may cause miscarriage, congenital anomalies, or severe neonatal complications. This cross-sectional study was conducted among 367 pregnant women attending hospitals in District Dir Upper, Khyber Pakhtunkhwa, Pakistan, to evaluate the seroprevalence of T. gondii and associated risk factors. Blood samples were analyzed using Immunochromatographic Test (ICT) for initial screening, and positive cases were confirmed by Enzyme-Linked Immunosorbent Assay (ELISA). Overall, 34.6 % (127/367) of women tested positive. While no significant differences were observed across age groups, gestational trimesters, or abortion history, higher prevalence was noted in women …

Straw Cover Increases Garden Soil Microbial Biodiversity, Emory Walker, Mara Welty, Emma Creviston

The Journal of Purdue Undergraduate Research

No abstract provided.

A Comparison Of White-Light And Monochromatic Led Sources For Antimicrobial Photodynamic Inactivation Of Staphylococcus Aureus, Emily Simmons

The Journal of Purdue Undergraduate Research

Drug-resistant bacteria are an ongoing public health crisis for which alternative treatments are needed. One alternative is antimicrobial photodynamic inactivation (aPDI), which uses potent photosensitizers and light irradiation to damage the bacteria. Our standard light source used in aPDI is a single-wavelength light source at 405-nm; however, we evaluated a white-light source for similarities in the resulting aPDI activities. This is done by comparing aPDI experiments using S. aureus and its methicillin-resistant strains (MRSA) conducted with either the white LED light source or the 405-nm LED light source. Statistical analysis using t-tests revealed no significant differences in the aPDI activities …

Development Of Broadly Protective Vaccines Against New World Arenaviruses, Brian B. Gowen

Funded Research Records

No abstract provided.

Effects Of Supplemental Led Lighting And Biofertilizer On Yield And Fruit Quality Of Japanese Strawberry Cultivars In Indonesia, Reginawanti Hindersah, Febby Fitriyani, Kenji Endo, Masakazu Nakayama, Syariful Mubarok, Gita Bina Nugraha

Jurnal Kultivasi

Growing strawberries in soilless substrates in the greenhouse relies on fertilizers and supplemental light to boost yield and fruit quality. The research evaluated the properties of the biofertilizer and its effectiveness on the yield of Japanese strawberry cultivars Nanatsuboshi and KS-75 under controlled greenhouse conditions, with and without light-emitting diodes (LED) as supplemental light. The cell viability and plant-growth-promoting properties of a liquid consortium biofertilizer consisting of nitrogen-fixing bacteria and phosphate-solubilizing microbes, were characterized. Laboratory analysis confirmed the biofertilizer's composition, and a greenhouse experiment using a completely randomized design tested treatments of biofertilizer, LED, and their combination. The biofertilizer contained …

Effects Of Integrated Biological And Chemical Fertilization On Pecco And Banji Shoot Development In Tea Plants, Intan Ratna Dewi Anjarsari, Muhammad Raihan Abdillah Farros, Santi Rosniawaty

Jurnal Kultivasi

Tea productivity and quality are largely determined by shoot structure, particularly the balance between pecco shoots (tender buds and young leaves) and banji shoots (older, less productive shoots). Conventional reliance on inorganic fertilizers often enhances overall growth but does not necessarily improve shoot structure, while biofertilizers alone provide limited nutrient availability. This study aimed to evaluate the effects of combining microbial-based liquid biofertilizers with inorganic fertilizers on the structure of tea shoots. The experiment was carried out on seed-derived tea plants using a randomized block design with several fertilization treatments, including sole biofertilizer, sole inorganic fertilizer, and their combinations. The …

The Effects Of Nanobubble Fertigation And Soil Conditioners To Improve Nutrient Dynamics, Soil Microbial Activity, And Chili Productivity, Betty Natalie Fitriatin, Euis Ahah Rokayah, Elsa Naila Elmyra, Tualar Simarmata, Nicky Oktav Fauziah, Hanif Fakhrurroja

Jurnal Kultivasi

Drip fertigation is a fertilization method that integrates nutrient delivery with an irrigation system, which is capable of optimizing the direct delivery of nutrients to the root zone. This experiment aims to investigate the effect of drip fertigation with nanobubble technology, and soil conditioners on the population of Phosphate-Solubilizing Bacteria (PSB) and Azotobacter spp., available phosphorus, total nitrogen, growth, and yield of red chili. The study used a Strip Plot Design with two factors and three replications. The first factor was nutrient application (solid NPK fertilizing as control; drip fertigation; and drip fertigation with nanobubble technology), and the second factor …

Role Of Cellular Stress Responses In Innate Immune Defense Against Acute Respiratory Infections, Amit Sharma

LSU Doctoral Dissertations

The endoplasmic reticulum (ER) stress sensor inositol-requiring enzyme 1α (IRE1α) is an important regulator of innate immune cells. However, its role in pulmonary innate host defenses remains poorly understood. This dissertation elucidates the dual, context-dependent role of IRE1α in host defense against methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. We demonstrate IRE1α’s function as both a detrimental mediator of acute pathology and an essential facilitator of innate immune memory. Our work revealed that acute IRE1α activation during primary MRSA infection is detrimental. In lungs and alveolar macrophages (AMs), IRE1α is activated in response to MRSA infection. Consequently, IRE1α activation triggers a hyperinflammatory …

Microplastic Exposure Alters Tubulin Leading To Alterations In Insulin Secretion By Pancreatic Beta Cells, Anakaren Garcia

Honors Program Theses and Research Projects

Abstract

Diabetes mellitus is a metabolic disorder characterized by elevated blood glucose levels due to impaired insulin secretion or diminished cellular response to insulin (resistance). Pancreatic β-cells depend on a well-organized cytoskeleton, particularly microtubules composed of α- and β-tubulin heterodimers, to transport insulin granules to the plasma membrane during glucose-stimulated insulin secretion (GSIS). Disruption of microtubule organization can impair granule trafficking and reduce insulin release. However, emerging environmental toxicants such as microplastics that interfere with β-cell cytoskeletal function remains largely unexplored.

Microplastics (MPs) are small plastic particles (< 5 mm) that have become widespread environmental contaminants and can enter biological systems. Previous studies have shown that MPs can induce cellular stress and protein misfolding, but their effects on microtubules in pancreatic β-cells are not well characterized. This study investigates whether exposure to fluorescent polystyrene microplastics alters microtubule organization and insulin secretion in βTC-6 cells.

βTC-6 cells were treated with 10 µg/mL of fluorescent polystyrene microplastics for …

Exploring The Role Of Faecalibacterium Prausnitzii Metabolites In Modulating Fatty Acid Metabolism And Protecting Hepg2 Cells During Induced Steatosis, Morgan Martin, Emerald Cole

Student Scholar Symposium

The obesity epidemic has risen to astronomical numbers with over 650 million adults being classified as obese (BMI≥30). Obesity is of critical concern as excess body fat storage is a comorbidity to various diseases including type-2 diabetes, cardiovascular disease, and cancer. Although obesity has classically been attributed to genetics and unhealthy lifestyle choices, there is a growing interest in other factors affecting obesity, including the gut microbiome. For example, mice lacking a microbiome are resistant to weight gain even when placed on a high-calorie diet. It can then be concluded that bacteria and the metabolites they produce can dramatically affect …

Advancing Louisiana's Cropping Systems: Sustainable Bioenergy Production, Cover Crops, And Technology Integration, Pedro R. Carrillo

LSU Doctoral Dissertations

The adoption of cover crops in Louisiana is lower than the national average, underscoring the need for region-specific research to address environmental challenges and demonstrate the short-term benefits of these practices within existing production systems. This research evaluated the integration of cover crops (CC) in energy cane (Saccharum spp.) and no-till cotton systems, focusing on their effects on soil health, nitrogen (N) management, and biomass production. Soil health indicators (SHIs), including enzymatic activities (β-glucosidase, β-glucosaminidase, and urease), protein N, inorganic N concentrations (nitrate and ammonium), soil organic matter (SOM), and microbial community composition assessed through ester-linked fatty acid …

Ecology Of Subaerial Algae: Photosynthetic Capacity As A Function Of Relative Humidity In A Naturally- Occurring Association, James A. Nienow

Georgia Journal of Science

Subaerial algae are defined by their ability to grow on surfaces exposed directly to the air. We are currently investigating the nature of the adaptations that allow these unicellular microorganisms to form rich growths in an environment subjected to repeated and prolonged periods without liquid water. It is well known from laboratory studies that at least some members of the group are able to sustain metabolic activity using water vapor at high relative humidity. However, data concerning the significance of this ability in natural populations are almost completely lacking. To help fill in this gap, we tracked the photosynthetic capacity …

The Triangular Interaction Between Dietary Polyphenols, Gut Microbiota, And Metabolic Syndrome, Emily Bayliss

Senior Honors Theses

Type 2 diabetes mellitus (T2DM) is a growing global health concern characterized by peripheral insulin resistance as well as impaired insulin secretion from pancreatic β-cells. Emerging evidence suggests that the gut microbiome, specifically gut dysbiosis, an imbalance in the gut microbiome, is a critical modulator of the pathophysiology of T2DM. Dietary polyphenols, a diverse group of bioactive compounds that are abundant in plant-based foods, have recently gained attention for their potential to attenuate metabolic disorders through their antioxidant and anti-inflammatory properties as well as through modulating the composition and activity of gut microbes, thereby attenuating dysbiosis. However, the diabetic state …

Twim #261: Overwhelming Microbial Greatness, Jenny Stoval, Briana Lanzarotta, Luke Boseman, Nicole L. Podnecky, Angela Wilson

School of Medical Diagnostics & Translational Sciences Publications

Podcast annotation TWiM #261: Overwhelming Microbial Greatness from the weekly podcast series "This Week in Microbiology" (TWiM), a podcast where experts in microbiology discuss academic papers in their field in an informal way.

Advancing The Virus Diagnostic Toolkit: Development Of Accurate And Reliable Artificial Virus-Mimicking Positive Controls And Crispr-Based Detection, Habeeb Yinka Atanda

Graduate Theses and Dissertations

Accurate and reliable detection of plant viruses is critical for protecting berries and other economically important crops. Yet diagnostic programs face persistent challenges with positive control availability, biosafety concerns, and specificity limitations. This thesis advances the diagnostic toolkit for berry viruses through three complementary innovations that address fundamental gaps in current detection methodologies. First, this research developed and validated virus-mimicking artificial positive controls (ViMAPCs) for diverse viruses affecting berry crops for endpoint PCR applications. ViMAPCs incorporate size differentiation, which enables immediate visual gel band discrimination between control and natural infection signals. Amplification efficiency analysis demonstrated close correspondence with true-positive controls …

Fungal Biodiversity, Microbial Communities, And Ecosystem Function In Non-Perennial Streams, Charles T. Bond

Dissertations

A global majority of steams are non-perennial, drying at some point in time and space. Despite the vital roles that fungi and other microbes play in stream ecosystems, most research on stream microbiomes comes from perennial (continuously flowing) streams. The present series of studies addresses this research gap by examining microbial community composition and function in non-perennial streams, with an emphasis on fungi. Chapter I reviews existing scientific literature on the ecological processes that shape microbiome structure and function in non-perennial streams and outlines the varieties of fungi that may live there. Chapter II uses rDNA metabarcoding to survey fungal …

Structure And Function Studies On Trna Splicing Endonuclease, Justin G. Underwood

Dissertations and Theses (Open Access)

A subset of eukaryotic pre-tRNAs have introns that must be spliced out to become mature molecules capable of functioning in translation. This essential processing step is performed by tRNA splicing endonuclease (TSEN), a highly conserved heterotetramer with two catalytic and two structural subunits. In addition to this conserved function, archaeal TSEN also processes pre-rRNA and yeast TSEN cleaves some mRNAs that encode mitochondrial proteins to initiate mRNA degradation. Interestingly, single amino acid mutations in TSEN cause the human Mendelian disease pontocerebellar hypoplasia (PCH) by an unknown mechanism. Recently, several groups have determined the structure of human TSEN, revealing similarities and …

Investigating The Impacts Of Azole Antifungals On Growth Of Cryptococcus Neoformans, Gnanambika Sindhe

All Theses

Cryptococcus neoformans, an opportunistic fungal pathogen is responsible for cryptococcosis, leading to approximately 181,000 deaths annually, predominantly in regions such as Sub-Saharan Africa. Fluconazole, a widely used fungistatic azole, is often administered due to its relative affordability and lower toxicity. However, resistance to fluconazole in C. neoformans can arise through aneuploidy, complicating treatment efforts. This study aims to deepen our understanding of resistance mechanisms to azole drugs by comparing fluconazole with other azoles, including both clinical and agricultural azole antifungals. Disk diffusion assays were performed to evaluate the ability of C. neoformans to develop resistance to these compounds, focusing …

Requirement Of Prepiilin Peptidase Activity For Variovorax Paradoxus Eps Flp/Fap Pilus Assembly, Jenny L. Lanthripp

Electronic Theses, Projects, and Dissertations

Variovorax paradoxus is a Gram-negative aerobic bacterium present in both soil and the human oral microbiome. This species contributes to biotransformation of xenobiotics and promotes plant growth. Interestingly, although the genome of strain EPS lacks the flagellum operon annotated in strain S110, the microbe remains motile, and flagella can be observed microscopically. To investigate this unexpected phenotype, motility mutants were enriched from a Tn5 mutant library using a liquid culture settling strategy. A total of 122 isolates were screened for motility defects, and 57 exhibited significantly reduced motility compared to the wild type. Rescue cloning revealed that over 60% of …

The Microstructure Of Metastatic Bone Lesions Suggests Tumor Mediated Alterations In Bone Mineralization, Hanwen Fan, Zhan Xu, Carla Berrospe Rodriguez, Noah Dover, Andrei Demkov, Morgan Lilly, Guillermo Aguilar, Larry J Suva, Xiang H-F Zhang, Yuxiao Zhou

Faculty, Staff and Students Publications

Breast, prostate and lung cancer cells frequently metastasize to bone, leading to disruption of the bone microstructure. This study utilized mechanical testing coupled with micro-CT imaging, digital volume correlation (DVC), and atomic force microscopy (AFM) nanomechanical testing to examine the mechanical property variations in mouse long bones (tibia) with metastatic lung cancer cell involvement, spanning from the whole-bone scale to the microstructural level. In addition, we also investigated how metastatic invasion alters the morphology of hydroxyapatite nanocrystals in bone at the nanometer scale. The biochemical composition within metastatic lesions was assessed using Raman spectroscopy and correlated with AFM mechanical testing …

Lilrb4 Regulates Circadian Disruption-Induced Mammary Tumorigenesis Via Non-Canonical Wnt Signaling Pathway, Olajumoke Ogunlusi, Mrinmoy Sarkar, Kayla Carter, Arhit Chakrabarti, Devon J Boland, Tristan Nguyen, James Sampson, Christian Nguyen, Danielle Fails, Yava Jones-Hall, Loning Fu, Gus Wright, Da Mi Kim, James J Cai, Bani Mallick, Alex C Keene, Jeff R Jones, Tapasree Roy Sarkar

Faculty, Staff and Students Publications

Epidemiological studies have shown that circadian rhythm disruption (CRD) is associated with the risk of breast cancer. However, the role of CRD in mammary gland morphology and aggressive basal mammary tumorigenesis and the molecular mechanism underlying CRD-induced carcinogenesis remain unknown. To investigate the effect of CRD on aggressive tumorigenesis, a genetically engineered mouse model of aggressive breast cancer was used. The impact of CRD on the tumor microenvironment was investigated using the tumors from LD12:12 and CRD mice via scRNA-seq, flow cytometry, multiplexing immunostaining, and realtime PCR. The effect of LILRB4-immunotherapy on CRD-induced tumorigenesis was also investigated. Here we investigated …

Functional Analysis Of Ftsa-Mediated Recruitment Of Ftsk In Escherichia Coli, Abbigale Perkins

Dissertations and Theses (Open Access)

Bacterial cytokinesis requires precise coordination between cytoplasmic and periplasmic components of the divisome to ensure that membrane constriction and chromosome segregation occur in synchrony. The actin-like protein FtsA plays a central role in this process by tethering FtsZ to the membrane and recruiting downstream division proteins. Despite its essential function, the mechanisms by which FtsA coordinates divisome activation and the recruitment of late-acting proteins remain incompletely defined. To address this, the role of FtsA in activating septal synthesis and recruiting the DNA translocase FtsK was examined using mutational analysis in Escherichia coli.

The FtsA^{M96E R153D} variant, which has …