Microbiology Commons^™

Assessing The Role Of The Microbiome, Parasite Infections, And Movement In Avian Health, Olivia N. Choi

Electronic Theses and Dissertations

Avian health encompasses the physical, physiological, and behavioral well-being of birds. Assessing avian health is not only important for the conservation and management of wild birds and the recreational economy, but also for the management of infectious diseases that threaten public health and agriculture. Birds, comprising approximately 10,000 species and an estimated 50 billion individuals worldwide, are known to be involved in the spread of pathogens, some of which are zoonotic (from animals to humans), such as avian influenza and West Nile viruses. Individual measures of avian health may include physical measurements (e.g., body mass, wing length), pathogen infection status, …

Pseudomonas Aeruginosa Enhances Fluconazole Activity Against Candida During Polymicrobial Infection, Siham Hattab

Electronic Theses and Dissertations

Polymicrobial infections pose a significant challenge in the field of medicine due to our incomplete understanding of how pathogens interact during infection and how these interactions impact the effectiveness of drug treatments. Among the opportunistic pathogens, Candida albicans and Pseudomonas aeruginosa stand out, as they are often found in similar infection sites, such as burn wounds, the lungs of patients with cystic fibrosis and those on mechanical ventilation. Candida albicans is an opportunistic fungus responsible for invasive candidiasis, a condition associated with a high mortality rate of 40% in hospitals. Pseudomonas aeruginosa, on the other hand, is the primary pathogen …

Interactions Between Streptococcus Agalactiae And Candida Albicans Affect Persistence And Virulence, Kathryn Patenaude

Electronic Theses and Dissertations

Streptococcus agalactiae (Group B Streptococcus or GBS), a Gram-positive bacterium, and Candida albicans, a polymorphic fungus, are commensal microbes in most of the population they colonize but are also capable of causing severe and sometimes fatal infections in certain patient groups. Both organisms share similarities including the colonization the same tissue environments and causing infections in specific patient groups including those who are newborn, pregnant, suffering from chronic conditions like diabetes and HIV, as well as elderly patients. Previous research discovered that GBS and C. albicans can synergize to enhance the colonization of GBS in the bladders of mice, but …

Investigating The Impact Of Prophages On Bacterial Fitness Of Streptococcus Agalactiae, Caitlin Wiafe-Kwakye

Electronic Theses and Dissertations

Streptococcus agalactiae (Group B Streptococcus or GBS) is a common bacterium found in pregnant women that can cause severe infections in neonates. Although detecting maternal colonization and administering antibiotics during labor can prevent early-onset GBS disease in neonates, antibiotics negatively affect newborns' microbiota, leading to complications like gastrointestinal disorders and immune system dysregulation. Therefore, alternative therapeutic measures are necessary to improve maternal and neonatal outcomes. Understanding GBS disease pathology and developing effective preventive measures and treatments is essential. GBS evolves from a commensal bacterium to an invasive disease-causing pathogen using various mechanisms, such as adapting to the host immune response, …

Characterization Of Manganese-Induced Neurodegenration In C. Elegans Treated With Winterberry Leaf Extract, Brendan Moline

Honors College

Neurodegeneration is a condition present in Alzheimer’s disease (AD) and Parkinson’s disease (PD) in which the cells of the nervous system experience loss of function and death. Around the world, each year PD and AD affect 6.2 million and 29.8 million people, respectively, with the exact causes remaining unknown. Manganese (Mn) is a transition metal which is essential for human survival in trace concentrations. However, overexposure to Mn can induce neurodegeneration through the accumulation of reactive oxygen species and the eventual onset of oxidative stress. An extract produced from winterberry leaves (Ilex verticillata) exhibits antioxidant properties as it has been …

Evaluating Edna Metabarcoding As A Mic-Roe-Scopic Net To Catch Salmon Pathogens, Noah Burby

Honors College

Wild Atlantic salmon in the Gulf of Maine (GOM) is a Distinct Population Segment (DPS) that has been listed since 2000 as endangered by the U.S. Fish and Wildlife Service (USFWS) and the National Oceanic and Atmospheric Administration (NOAA). The current challenge is year-over-year decreases in the number of mature salmon returning to the Penobscot River for reproduction. Early detection of pathogen presence could allow for the identification of infection and the application of corrective measures. Environmental DNA (eDNA) is simply DNA that is collected from environmental samples (e.g., water, air, and soils), which consists of whole microorganisms and genetic …

Weaving An Interdisciplinary Microbiome Career Using Threads From Different Ecosystems, Sarah Hosler

Electronic Theses and Dissertations

Animals have trillions of microorganisms living in or on many body sites, these communities of microorganisms are called microbiomes. Microbiomes are typically host-specific, and a lot of information about the host can be determined from investigating them. Microbiome research has many real-world applications, and this thesis utilizes the One Health perspective, which acknowledges the connection of humans, animals, and environments, and emphasizes the need for collaborative, interdisciplinary research. The first interdisciplinary project is an investigation into the bacteria in wild and cultured Atlantic deep-sea scallop, Placopecten magellanicus larvae. Adults in hatcheries can be induced to spawn, but the last two …

Many Questions Remain Unanswered About The Role Of Microbial Transmission In Epizootic Shell Disease In American Lobsters (Homarus Americanus), A Perspective Article, Suzanne Ishaq, Sarah M. Turner, M. Scarlett Tudor, Jean Macrae, Heather Hamlin, Joelle Kilchenmann, Grace Lee, Deborah A. Bouchard

Journal Articles

Despite decades of research on lobster species’ biology, ecology, and microbiology, there are still unresolved questions about the microbial communities which associate in or on lobsters under healthy or diseased states, microbial acquisition, as well as microbial transmission between lobsters and between lobsters and their environment. There is an untapped opportunity for metagenomics, metatranscriptomics, and metabolomics to be added to the existing wealth of knowledge to more precisely track disease transmission, etiology, and host-microbe dynamics. Moreover, we need to gain this knowledge of wild lobster microbiomes before climate change alters environmental and host-microbial communities more than it likely already has, …

Determining Effects Of Management Practices On Potato Early Dying And Soil Microbiome And Assessing Risk Of Fungicide Resistance In Verticillium Dahliae, Kedi Li

Electronic Theses and Dissertations

Potato early dying (PED) is a yield-constraining soilborne disease of potato, caused by Verticillium spp. with V. dahliae being the predominant causal agent. Since the pathogen inhabits soil for long periods, PED management aims to reduce the population of V. dahliae in soil. Benzovindiflupyr and azoxystrobin are effective chemicals and frequently used in the control of V. dahliae. In this study, field trials were conducted at Aroostook Farm, Presque Isle, ME in 2019 and 2020. Chemical and biological products have been studied for PED control, and fungicide resistance was also examined. To evaluate fungicide resistance, benzovindiflupyr was characterized on …

Retroviral Infection Dynamics In Maine's Wild Turkeys, Stephanie A. Shea

Electronic Theses and Dissertations

Widespread wild turkey reintroductions in the late 1900s have led to increases in population density and geographic distribution across North America. This rapid population expansion has put them into proximity with closely-related wild and domestic avian species, increasing the risks of pathogen transmission. Lymphoproliferative disease virus (LPDV) is an avian oncogenic retrovirus detected in wild turkeys in 2009, and previously known to infect domestic turkeys. Following its initial detection, surveys reported variable LPDV prevalence across eastern North America with most wild turkeys being asymptomatic, however diagnostic cases revealed 10% mortality of LPDV-infected individuals. Given its recent detection, little is known …

Impact Of Probiotics On Black Soldier Fly Larvae Transmission Of Stenotrophomonas Maltophilia, Emily Marie Mclaughlin

Honors College

Stenotrophomonas maltophilia is an opportunistic pathogen which can cause a variety of infections, especially in immunocompromised individuals. It has recently been found that black soldier flies can act as carriers for S. maltophilia (Callegari et al., 2020). I have investigated how probiotics impact their vector capabilities. Black soldier fly larvae have been fed substrate spiked with S. maltophilia. After several days of feeding, the larvae were investigated by PCR and plating (Sveensson-Stadler et al., 2011). Two groups of larvae were fed with potatoes infected with S. maltophilia. Persistence of S. maltophilia was determined using PCR by taking samples …

Characterizing The Role Of Prophages On Whib7 Expression And Antibiotic Resistance In Mycobacterium Chelonae, Jaycee J. Cushman

Electronic Theses and Dissertations

Mycobacterial pathogens are responsible for an ongoing public health crisis. Mycobacterium abscessus is the causative agent of lung infections that disproportionately affect immunocompromised individuals and is the most intrinsically antibiotic-resistant bacterial species known. These characteristics make M. abscessus infections difficult to treat, with a success rate of only 45%. While some extensively resistant isolates are caused by mutations in drug targets, others appear to be a result of increased intrinsic drug resistance. Common among these strains is the presence of integrated viral genomes (prophage) that are known to contribute to fitness and antibiotic resistance in other pathogens but whose roles …

Understanding The Adhesion Mechanism In Mycelium-Assisted Wood Bonding, Wenjing Sun

Electronic Theses and Dissertations

The increasing environmental awareness has led to an increased interest in developing more sustainable materials as alternatives to petroleum-derived products. Among different nature-based products, fungal-mycelium-based bio-composites have gained considerable attention in various applications. Multiple materials with different densities and structures and potential applications can be fabricated by inoculating filamentous white-rot fungi in lignocellulosic materials and other substrates. Different from lower-density as-grown foam-like mycelium composites, higher-density mycelium-lignocellulosic panels have the potential to replace commercial particleboard and fiberboard bonded by petroleum-based resins. This kind of composite can be produced by directly adding heat and pressure to the low-density foams or by assembling …

Deciphering The Perpetual Fight Between Virus And Host: Utilizing Bioinformatics To Elucidate The Host's Genetic Mechanisms That Influence Jc Polyomavirus Infection, Michael P. Wilczek

Electronic Theses and Dissertations

JC polyomavirus (JCPyV) is a human-specific pathogen that infects 50-80% of the population, and can cause a deadly, demyelinating disease, known as progressive multifocal leukoencephalopathy (PML). In most of the population, JCPyV persistently infects the kidneys but during immunosuppression, it can reactivate and spread to the central nervous system (CNS), causing PML. In the CNS, JCPyV targets two cell types, astrocytes, and oligodendrocytes. Due to the hallmark pathology of oligodendrocyte lysis observed in disease, oligodendrocytes were thought to be the main cell type involved during JCPyV infection. However, recent evidence suggests that astrocytes are targeted by the virus and act …

Understanding The Role Of Prophage Encoded Polymorphic Toxins In Mycobacterial Superinfection Immunity And Drug Resistance, Dakota Archambault

Honors College

Mycobacterium abscessusis the leading cause of lung infection in cystic fibrosis patients and is often resistant to all antibiotics. There is an urgent need for alternative therapies such as lytic bacteriophage (viruses that infect bacteria). Phage therapy has been successful in the treatment of a drug-resistantM. abscessusinfection in a teenaged cystic fibrosis patient but there are challenges to broad use as most M. abscessusisolates are highly resistant to lytic bacteriophage infection. Prophage, or integrated bacteriophage genomes within the M. abscessusgenome, likely defend against phage superinfection via prophage-encoded viral defense systems. The Molloy lab has shown that the Mab cluster R …

An Investigation Of The Relationship Between Black Soldier Fly Larvae Pathogen Suppression And Growth Substrate In Relation To Maine Agricultural Industries, Haley Morrill

Honors College

Insects are promoted as cost-effective and sustainable protein sources for animal feed. Their utilization may help to avoid a predicted global protein shortage. Black soldier fly (Hermetia illucens) larvae (BSFL) grow on organic wastes, converting these wastes into larval biomass which can fulfill this purpose. Potential benefits of using BSFL to remediate organic wastes include reduction of waste mass and bacterial load, along with the sale of larvae as a protein supplement. BSFL suppress the growth of some Gram-positive and Gram-negative human pathogens in these substrates; though suppression of Bacillus cereus, a spore-forming bacterium that causes food-poisoning, …

Infection And Diet-Induced Gut Dysbiosis: Impact On Sleep Quality In Danio Rerio, Benjamin Williams

Honors College

A known bidirectional relationship between intestinal microflora and the central nervous system, coined the gut-brain-axis, has stimulated work on the association between gut dysbiosis and inflammation, and sleep quality. Previous studies in the Hayes Lab have reported that a high fat (HF) diet was correlated with immobile phases, a marker of low motility during sleep found in some neurological disease and sleep duration[1]. Long sleep duration (>1 S.D. above norms for age) is associated with poor sleep quality or sleep fragmentation in participants who are overweight or obese according to body mass index values[2]. The current work utilizes a …

Characterizing The Diversity Of Cluster R Prophage In Mycobacterium Abscessus, Colin Welch

Honors College

Mycobacterium abscessus is a mycobacterial pathogen responsible for pulmonary and disseminated infections in susceptible individuals and often is resistant to all antibiotic therapies, with cure rates ranging from 25% to 58% (Degiacomi et al., 2019).Investigating the mechanisms of extensive resistance in M. abscessus lends opportunities to develop more effective treatments. Prophage, viral sequences integrated into bacterial genomes, contribute to virulence and fitness in many bacterial pathogens including Escherichia coli O157:H7 and Vibrio cholerae (Fortier & Sekulovic, 2013). Yet, prophage in pathogenic mycobacteria are not well understood or studied. Recent work has demonstrated that the Mycobacterium chelonae prophage, McProf can function …

The Role Of Accessory Domain In Cpsa Function And Capsule Production In Group B Streptococcus, Gina Difederico

Honors College

Group B Streptococcus (GBS) can be found in the vaginal and genitourinary tract of females, as well as the genitourinary tract of males, where it behaves as a commensal organism. However, as an opportunistic pathogen, GBS has the capability to infect the immunocompromised, making it a major threat to neonates and fetuses. The pathogen can be passed from mother to baby either in utero or during birth. The capsule, which is a polysaccharide coating on the outside of the cell, is considered the most important virulence factor in GBS.Expression of capsule plays a role in evasion of the host immune …

Examining The Function Of Protein Acyltransferase Via The Dhhc Domain Of The Paz5 Protein In The Organism Dictyostelium Discoideum, George M. Stuart-Ranchev

Electronic Theses and Dissertations

Protein S-palmitoylation plays a crucial role in many biological systems. S-palmitoylation involves the post-translational attachment of palmitate to a cysteine residue through a reversible thioester linkage. S-Palmitoylation is used to modify both integral and membrane proteins, many of which are involved in intracellular trafficking, membrane localization, and signal transduction pathways. Intracellular palmitoylation is mediated by a family of protein acyltransferases (PATs). PAT mutations are associated with neurological diseases and cancer progression. Proteins in the PAT family are defined by the presence of a 51-amino acid cysteine-rich domain (CRD), which contains a highly conserved aspartate-histidine-histidine-cysteine (DHHC) motif. The …

Dissection Of Molecular Mechanisms By Which Human Host Factors Regulate Jc Polyomavirus Internalization, Colleen Mayberry

Electronic Theses and Dissertations

Viruses require a host cell in order to replicate. Infection and the onset of disease result from direct virus-host cell interactions. My dissertation research is focused on understanding how a common human virus, JC polyomavirus (JCPyV), activates specific host cell factors to cause infection. When people are immunocompromised, JCPyV infection may exacerbate into the onset of progressive multifocal leukoencephalopathy (PML), a fatal neurodegenerative disease. Individuals with the greatest risk for the development of PML are those living with multiple sclerosis or infected with HIV. Unfortunately 50-80% of the population is infected by JCPyV, putting individuals at risk for developing PML. …

Does Circularizing Source-Separated Food Waste Present A Risk To Our Food?, Astha Thakali

Electronic Theses and Dissertations

About a third of the food produced annually is wasted. Food waste recycling can be a way to close the loop and attain a more sustainable food system, however, the system must be carefully monitored and managed to avoid the introduction and build-up of contaminants. To study the potential presence of contaminants in food waste, source-separated food waste was collected and screened for five classes of contaminants (physical contaminants, heavy metals, halogenated organic contaminants, pathogens, and antibiotic resistance genes) from two separate regulatory environments (voluntary vs mandated food separation). The regulatory environment did not affect the level of contamination, except …

Quantification Of Interactions Between Influenza Hemagglutinin And Host Cell Phosphoinositides By Super-Resolution Microscopy, Matthew T. Parent

Electronic Theses and Dissertations

The influenza viral membrane protein hemagglutinin (HA) forms dense nanoscale clusters on host cell plasma membranes (PM), but the mechanisms that direct HA clustering are not well understood. Previous studies have observed HA associated with actin rich regions of the PM, but there are no known direct interactions between HA and actin. Phosphatidylinositol 4,5-biphosphate (PIP2) is a signaling lipid in the PM which can regulate the actin cytoskeleton, and actin comets initiated by PIP2 are known to be exploited by HA to reach the PM of infected cells. PIP2 is also used by other viruses, such as HIV and Ebola, …

Development Of A High-Throughput Platform For The Determination Of Antiviral Therapeutics, Mason A. Crocker

Electronic Theses and Dissertations

JC polyomavirus (JCPyV) persists in up to 90% of the global human population. In healthy individuals, the virus resides within the kidneys resulting in a low-level infection. However, in severely immunocompromised individuals, the virus can migrate to the central nervous system (CNS), causing the demyelinating disease progressive multifocal leukoencephalopathy (PML). Currently, this debilitating disease has no clinical therapeutic options and is almost universally fatal. Specifics of the JCPyV infectious cycle, as well as the limitations of traditional laboratory techniques, have previously hindered the search for antiviral agents with the potential to prevent or treat JCPyV infection. To this end, a …

Gershman (Melvin) Papers, 1959-1992, Special Collections, Raymond H. Fogler Library, University Of Maine

Finding Aids

Melvin (Mel) Gershman was born in 1927. He received a M.Sc. Degree in 1957 from the University of Massachusetts and came to the University of Maine in 1958 as an assistant professor of microbiology and animal pathology. In 1963, he was appointed full professorship and in 1977 he became Professor of Microbiology and Animal Veterinary Sciences. Professor Gershman research focused on Enteric bacteria such as Salmonella and Escherichia Coli. His research led to the development of a Serotyping and Phage Typing Center at the University of Maine.

Gershman received numerous awards during his career, including in 1977 the University …

The Potential For Dickeya Dianthicola To Be Vectored By Two Common Insect Pests Of Potatoes, Jonas K. Insinga

Electronic Theses and Dissertations

Dickeya dianthicola (Samson) causing blackleg and soft rot was first detected in potatoes grown in Maine in 2014. Previous work has suggested that insects, particularly aphids, may be able to vector bacteria in this genus between plants, but no conclusive work has been done to confirm this theory. In order to determine whether insect-mediated transmission is likely to occur in potato fields, two model potato pests common in Maine were used: the Colorado potato beetle (Leptinotarsa decimlineata Say) and the green peach aphids (Myzus persicae Sulzer). Olfactometry and recruitment experiments evaluated if either insect discriminates between infected and …

Framing The Discussion Of Microorganisms As A Facet Of Social Equity In Human Health, Suzanne L. Ishaq, Maurisa Rapp, Risa Byerly, Loretta S. Mcclellan, Maya R. O'Boyle, Anika Nykanen, Patrick J. Fuller, Calvin Aas, June M. Stone, Sean Killpatrick, Manami M. Uptegrove, Alex Vischer, Hannah Wolf, Fiona Smallman, Houston Eymann, Simon Narode, Ellee Stapleton, Camille C. Cioffi, Hannah F. Tavalire

Animal and Veterinary Sciences Faculty Scholarship

What do “microbes” have to do with social equity? These microorganisms are integral to our health, that of our natural environment, and even the “health” of the environments we build. The loss, gain, and retention of microorganisms—their flow between humans and the environment—can greatly impact our health. It is well-known that inequalities in access to perinatal care, healthy foods, quality housing, and the natural environment can create and arise from social inequality. Here, we focus on the argument that access to beneficial microorganisms is a facet of public health, and health inequality may be compounded by inequitable microbial exposure.

Examining The Microbiome Of Porphyra Umbilicalis In The North Atlantic, Margaret Aydlett

Honors College

Marine macroalgae host a diverse microbiota. Bacteria are the most prominent group, and relationships between the algae and bacteria are complex and dynamic. The goal of this project was to examine the distribution and ASV diversity of Bacteria associated with Porphyra umbilicalis with special focus on some isolates, including studies of their temperature dependence and consideration of how they may affect Porphyra. Previous studies showed that some bacteria are required for normal algal morphology and growth. Porphyra umbilicalis is an abundant red macroalga found in the intertidal zone and is an important food for invertebrates. Because of its significance in …

Intravital Imaging In A Zebrafish Model Elucidates Interactions Between Mucosal Immunity And Pathogenic Fungi, Linda S. Archambault

Electronic Theses and Dissertations

Candida yeasts are common commensals that can cause mucosal disease and life-threatening systemic infections. While many of the components required for defense against Candida albicans infection are well established, questions remain about how various host cells at mucosal sites assess threats and coordinate defenses to prevent normally commensal organisms from becoming pathogenic. Using two Candida species, C. albicans and C. parapsilosis, which differ in their abilities to damage epithelial tissues, we used traditional methods (pathogen CFU, host survival, and host cytokine expression) combined with high-resolution intravital imaging of transparent zebrafish larvae to illuminate host-pathogen interactions at the cellular level …

Determining Key Residues Of The Lyt-R Domain In The Streptococcal Cpsa Protein, Mohammad Hashmi

Honors College

Streptococcus agalactiae or Group B Streptococcus (GBS), is a Gram-positive commensal bacterium that is harmless in healthy adults, yet causes systemic diseases in neonates, the elderly, and immunocompromised individuals. Neonates are at risk of GBS infection in utero or during delivery due to the colonization of the organism in the vaginal canal of between 15-30% of adult females. GBS can cause severe neonatal sepsis and meningitis, as well as chorioamnionitis, which can cause premature birth and stillbirth. GBS infection is greatly facilitated by the presence of a bacterial capsule; a protective, polysaccharide matrix surrounding the cell that plays a key …