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Exploration Of Enterococcus Faecalis Bacteriophages Diversity: Comprehensive Phylogenetic Analysis And Discovery Isolation Of Enterococcus Faecalis Phage From A Soil Sample In South Florida, Hailey N. Jauernick

All HCAS Student Capstones, Theses, and Dissertations

Enterococcus faecalis is a commensal bacterium found in the gastrointestinal tract, oral cavity, and vagina of humans, which can transition to pathogenic states, leading to diverse infections. Many E. faecalis infections are becoming progressively challenging to treat, stemming from the lack of effective antibiotic therapies against its virulence factors, including biofilm formation and antibiotic resistance. Phage therapy emerges as a promising alternative, targeting bacteria with minimal impact on host flora. However, despite phages' ubiquitous presence and potential applications in medicine and biotechnology, their diversity and ecological niches are vastly understudied. Here, we investigated the diversity of sequenced E. faecalis phages …

Mimicking Biofilms: Photosynthetic Assessments Of C. Reinhardtii In 3 Physical Forms, John Michael Roesgen

Biology ETDs

Oxygenic photosynthesis supports the majority of life on Earth through the capture of energy from sunlight and the assimilation of CO₂ into basic building blocks of cells. Microalgae are fast growing and account for about half of global photosynthesis. In addition, they can be cultivated and their metabolism can be redirected to generate additional useful products ranging from biofuels to pharmaceuticals. However, the efficiency of metabolite production is severely impacted by the slow diffusion of CO₂ through water and the high energetic costs of harvesting microalgae from liquid cultures. Microalgae grow in open water, but they also form …

The Antibacterial Efficacy Of Silver (I) Cyanoximates Against Streptococcus Mutans Ua159 Biofilm Growth And Infection In Galleria Mellonella Larvae, Jill Hughes

Honors Program Theses

Streptococcus mutans is the known etiological agent of dental caries. S. mutans’ virulence factors, namely biofilm formation and lactic acid fermentation, contribute to its pathogenic behavior within the oral cavity. Biofilms are thick, antibiotically resistant communities of bacteria that are much more difficult to treat than planktonic or free-floating bacteria. Continued misuse of antibiotics against dynamic communities, like biofilms, has led to increased research on non-antibiotic alternatives. Amongst these alternatives, there are silver and silver-based compounds. Silver is commonly incorporated into medicine due to its inhibitory and bactericidal effects and antibacterial properties. Silver (I) cyanoximates have demonstrated promising antibacterial activity …

Characterization Of The Clostridioides Difficile Glycosyl Hydrolase Ccsz, Brian Lowrance

Theses and Dissertations (Comprehensive)

Bacteria inhabit many of the harshest environments on Earth; persisting and thriving in conditions thought to be unsuitable for life. One common strategy to withstand these environments is the formation of a biofilm. Biofilm composition varies greatly, depending on the underlying community that produces it. Cellulose, a polymer consistently prevalent in biofilms, has been identified as a virulence factor in many pathogens and is suspected to be involved in pathogenesis by Clostridioides difficile. C. difficile is the #1 cause of hospital acquired diarrhea, which can range from mild to life-threatening infections. Biofilm formation is hypothesized to be involved in …

Biomass Estimation Of Marine Biofilms On Plastic Surfaces, Kian Banihashemi, Fernando Javier Gil

Biological Sciences

Plastics have become a major source of marine pollution, which threatens food safety and quality, human health, and marine ecosystems. Due to the drastic negative effects of plastics in a marine environment, alternative biodegradable plastics are being generated that are more eco-friendly and have less environmental impact. Though some of these plastics are known to biodegrade, the process of degradation for bioplastics has not been heavily studied in a marine environment. This pilot project sought to both quantify the process of biodegradation and compare across different methods for effectiveness of biomass estimation, which serves as an indicator of biodegradation. Plastics …

Periodic Spatial Disturbances Alter The Expression Of Quorum Sensing Virulence Factors In Pseudomonas Aeruginosa, Laura García-Diéguez

All HCAS Student Capstones, Theses, and Dissertations

Pseudomonas aeruginosa is an opportunistic pathogen associated with severe acute and chronic illnesses. Current antibiotic-based approaches fail to effectively treat P. aeruginosa infections due to the effectiveness and robustness of the quorum sensing signaling system (QS). Pathogenic bacteria, such as P. aeruginosa, employ this population density-dependent communication mechanism to confer antimicrobial resistance, propagate infection, and coordinate the expression of virulence factors, through the production and detection of autoinducing signaling molecules (AI). As such, there is a growing interest in developing novel non-antibiotic-based techniques to attenuate the pathogenicity of P. aeruginosa by disrupting the functionality of its QS system. Previous …

Ecology Of Periphyton In A Subtropical River Floodplain, Kamela De Gallardo

LSU Doctoral Dissertations

The Atchafalaya River Basin (ARB) in southcentral Louisiana, USA, is a large and biologically diverse floodplain surrounding the Atchafalaya River (AR), which is the largest distributary of the Mississippi River, receiving 30% of the combined daily discharge of the Mississippi and Red Rivers. Annual flooding facilitates exchange between the AR and its floodplain and is thought to give rise to the high productivity of the river-floodplain system. Primary production within the aquatic ARB is driven by periphytic algae, phytoplankton, and aquatic macrophytes, however, very little is known about periphytic algal assemblages in floodplain systems. In this study, artificial substrates were …

Inhibition Of Staphylococcus Aureus Biofilm By Variovorax Paradoxus, Esther Gomez

University of the Pacific Theses and Dissertations

Staphylococcus aureus is one of the leading causes of fatal nosocomial infections. Often, S. aureus can grow as a biofilm which protects the population from the surrounding environment. Strains of S. aureus are resistant to virtually all known antibiotics on the market. Variovorax paradoxus is a soil microbe with many unusual metabolic activities. It has been previously observed that, V. paradoxus can inhibit the growth of S. aureus when in co-culture. In this work we report on inhibition of S. aureus biofilm formation by V. paradoxus due to a suspected inhibitory soluble factor.

Identification Of The Role Of Swra In Copper Induced Poly-Gamma-Glutamic Acid Production In Bacillus Subtilis, Maya Addison

Scripps Senior Theses

Each year over 2.8 million Americans are infected by an antibiotic resistant strain of bacteria with over 35, 000 dying as a result (CDC). The lack of development of new antibiotics has renewed interest in the antimicrobial properties of copper. Gram positive bacterium such as Bacillus subtilis produce poly-gamma-glutamic acid (γ-PGA) to sequester excess copper ions. swrA has shown to be essential for proper activation of the pgs operon by phosphorylated DegU via an unknown mechanism. This study seeks to determine the role of swrA in copper induced gamma-PGA production and if swrA and ppsB are involved in copper resistance. …

Increasing The Frequency Of Periodic Spatial Disturbance Decreases Surface Attachment Protein Expression In Staphylococcus Aureus, Ivana M. Barraza

All HCAS Student Capstones, Theses, and Dissertations

Staphylococcus aureus is an opportunistic pathogen that can cause a variety of acute and chronic illnesses. The severity of these illnesses such as sepsis, necrotizing pneumonia, and toxic shock syndrome is measured through the virulence that S. aureus inflicts on its host. Methicillin-resistant S. aureus (MRSA) is commonly associated with secondary infections and is challenging to treat given the limited selection of antibiotics that are effective against it. Accordingly, novel approaches to reduce S. aureus pathogenicity are required. S. aureus regulates pathogenesis through a cell-to-cell communication system referred to as quorum sensing. Effective communication determines the production of two broad …

Disruption Of Pyoverdine Synthesis In Pseudomonas Aeruginosa Through Periodic Disturbance Of Biofilm Structure, Rebecca J. Quinn

All HCAS Student Capstones, Theses, and Dissertations

Infections due to bacteria were once easily treated using antibiotics. However, the effective shelf life of antibiotics is diminishing due to the rise and spread of antibiotic resistant bacteria. Accordingly, novel approaches to treating infections are required. Pseudomonas aeruginosa is a multi-drug resistant, biofilm forming opportunistic pathogen. A determinant of P. aeruginosa’s pathogenicity is pyoverdine, a siderophore that is used to sequester iron from the environment. After being produced by a bacterium, pyoverdine is secreted into the environment where it complexes with iron. The pyoverdine-iron complex is then returned to the bacteria through diffusion, where it drives the synthesis of …

The Effect Of Truncated Complement Constructs On Biofilm Formation, Protease Production, And Pigmentation, Cara L. Cothern

Honors Theses

The msaABCR operon regulates virulence factors in Staphylococcus aureus, a Gram-positive commensal organism that colonizes healthy individuals but can also be a human pathogen. These virulence factors include biofilm development, pigmentation, and extracellular protease production. The operon consists of the msaB gene, which produces a coding transcript, the msaA gene and the msaC gene, which produce noncoding RNAs, and msaR, which produces an antisense RNA. The latter three transcript regions of the operon are referred to as untranslated regions (UTRs) and are essential for the function of the operon, but only msaB encodes a protein. The mechanism of …

The Role Of Streptococci In Oral Periodontitis: Growth And Disruption Of Yellow Complex Bacteria, Megan Gordon

Theses and Dissertations (Comprehensive)

Periodontitis is described as the inflammation of the periodontium and affects millions of people worldwide. This disease is caused by biofilm growth of certain bacteria on the tooth surface, adjacent to the gum tissue in the oral cavity. There are currently treatments against severe periodontitis, such as oral surgery and use of broad-spectrum antibiotics, but they fail to target the specific bacteria associated with periodontitis. Socransky et al., (1998), identified the preponderance for specific organisms in distinct areas of the subgingival pockets to associate with different bacteria forming consortia and complexes. The yellow complex, containing facultatively anaerobic, Gram positive …

Characterization Of Psychromonas Aquimarina, A New Model Organism For Climate Change, Carrie Carpenter

Experiential Learning Projects

The current increase of average global temperature puts 25 to 35 percent of plant and animal species at an increased risk of extinction (Climate Change, 2018). Changing any environmental factor, such as increasing growth temperature, can significantly impact any organisms’ ability to survive. Because of the diversity of organisms on the planet, it is not feasible to study how each individually might adapt, but rather it is more efficient to study select organisms. This research focuses on a psychrophilic bacterium, Psychromonas aquimarina, which can survive in colder regions where most bacteria would not. This bacterium was chosen because climate change …

Coaggregation Patterns And Surface Characteristics Of Lactobacillus Rhamnosus Gg Under Varying Nutrient Conditions, Amanda Rielinger

Senior Honors Theses and Projects

Lactobacillus rhamnosus GG (LGG) is one of the best studied probiotic organisms. The ability of probiotics to adhere to other microorganisms and the intestinal epithelium is thought to play a major role in their protective functions. Coaggregation is an important mechanism for biofilm formation by microorganisms. The goals of this study were to examine the ways in which nutrient variation affects intercellular interactions between LGG and other gut microbes and the hydrophobic character of LGG. We hypothesized that nutritional variation may affect the ability of LGG to coaggregate and form biofilms and thus affect its probiotic characteristics and ability to …

Phenotypic And Transcriptomic Characterization Of Colonial Phase Variation In The Cholera Pathogen Reveals A Novel Smooth Biofilm-Defective Form, Bliss Nicole Lambert

LSU Doctoral Dissertations

Biofilm formation, through the production of Vibrio polysaccharide (VPS), greatly enhances the environmental fitness and pathogenic success of Vibrio cholerae. As a result of phase variation, V. cholerae can switch from a smooth form to rugose, whose cells produce excess VPS, resulting in highly structured biofilms and greater resistance to stress. To further characterize the reversible process of phase variation, we isolated three colonial lineages. Each lineage began with a smooth parent, N16961, and contained a rugose variant derived from the parent, N16961R, as well as a smooth revertant of the rugose, N16961SD. We found clear phenotypic and transcriptomic …

Isolation Of Stenotrophomonas Maltophilia Virus Bfi1: A Biofilm Inhibiting Phage, Thomas Edward Moran

College of Science and Health Theses and Dissertations

The bacterium Stenotrophomonas maltophilia is an emerging infectious pathogen of global concern. Due to its drug-resistant nature, there are limited treatment options available. A potential option for combating S. maltophilia infections is phage therapy, the medicinal use of viruses to treat bacterial infections. Stenotrophomonas phage Bfi1 was isolated from a soil sample using S. maltophilia clinical strain S18202. Transmission electron microscopy provided evidence that this phage is a member of the Siphoviridae family. Host range analysis showed that the phage successfully infected and lysed 30% of the S. maltophilia strains tested. Genomic analysis revealed that the phage contains approximately 32.2-56.5 …

Relationships Between Factors Influencing Biofilm Formation And Pathogen Retention In Complex Rhizosphere Microbial Communities, Aaron Coristine

Theses and Dissertations (Comprehensive)

Riparian wetlands are unique habitats facilitating all forms of life. The riverbanks of these environments provide ideal conditions for bacteria, plants, and higher organisms. Of particular interest to this research was the variation in microbial community structure at high, intermediate and poor water quality impacted areas. Assessing the capabilities of plants to retain microbial pathogens was identified. Root systems and corresponding soil are ideal locations for bacterial deposition, resulting in attachment at these areas. Biofilm production in these regions is important for long-term establishment, leading to persistence and potential naturalization. Opportunistic pathogens originating from mammalian fecal matter are introduced into …

Effect Of Ultrasonication On Biofilm Forming Ability Of Common Dairy Sporeformers, Taghreed Almalki

Electronic Theses and Dissertations

Sporeformers are common dairy contaminants, which are of a great concern to the dairy industry. Quality of dairy products is affected by these sporeformers such as Bacillus species, which are a significant cause of spoilage of dairy products. Thermal processes such as pasteurization have been used to inactivate pathogens, but some of the sporeformers and their endospores are resistant to such heat treatments. Beside thermal treatments, various new approaches are being developed to improve the quality of dairy products. Amongst these, ultrasonication is a promising non-thermal technique for the inactivation of thermoduric sporeformers and their endospores. Current study was carried …

The Effects Of Treating Multispecies Biofilms With Bacteriophage, Alexandria Francis Cooper

Master's Theses

Biofilms can be found in any environment within proximity to water and are problematic in an assortment of industries. Numerous efforts have been employed to dislodge biofilms including bacteriophages (viruses that infect bacteria). Phage remediation is a promising solution for combatting biofilms that form on catheters in long term use patients. These biofilms often result in catheter-associated urinary tract infections (CAUTIs) and are the most common type of healthcare related infection reported. Additionally, they result in longer hospital stays and increased morbidity. To date, most of the research on the topic focuses on single species biofilms, despite their rarity in …

Impact Of Biofilm Formation And Composition On Antibiotic Resistance In Environmental Isolates Of Escherichia Coli And Salmonella Spp., Raluca Tutulan

Theses and Dissertations (Comprehensive)

Escherichia coli and Salmonella spp., like most bacteria, prefer to grow in biofilms. These biofilms provide bacteria with protection from harsh environmental factors (such as desiccation and changes in pH), aid in the evasion of host immune responses and provide increased antibiotic resistance. Biofilms are present in non-host environments (e.g. water pipes) as well as in mammalian hosts (in the healthy gastrointestinal microbiota and in over 65% of nosocomial infections). Two important components utilized by E. coli and Salmonella spp. to form biofilms are cellulose and curli fimbriae. Curli fimbriae mediate the attachment of bacteria to abiotic surfaces and …

Purification And Characterization Of Bcsc; An Integral Component Of Bacterial Cellulose Export, Emily D. Wilson Ms

Theses and Dissertations (Comprehensive)

Biofilms are a growing concern in the medical field due to their increased resistance to antibiotics. When found in a biofilm, bacteria can have antibiotic resistance 10-1000 times that of their planktonic counterparts. Therefore, it is important to study the formation of biofilms. Cellulose biofilms are formed by Enterobacteriaceae, such as many Escherichia coli and Salmonella spp. strains. Biofilms provide these species with benefits including antimicrobial protection, development of bacterial communities, promotion of DNA exchange, uptake of nutrients, and, in the case of cellulose biofilms, immune system evasion. Cellulose biofilms are controlled by the Bacterial cellulose synthesis (Bcs) complex located …

Interaction Of Rhizobium Sp. Strain Irbg74 With A Legume (Sesbania Cannabina) And A Cereal (Oryza Sativa), Shubhajit Mitra

Theses and Dissertations

Rhizobium sp. IRBG74 (IRBG74) develops a classical nitrogen-fixing symbiosis with the legume Sesbania cannabina and also promotes the growth of rice (Oryza sativa), but not much is known about the rhizobial determinants important for these interactions. We hypothesize that Rhizobium sp. IRBG74 utilizes similar mechanisms to endophytically colonize both legume and cereal hosts. In this study, we analyzed the colonization of rice and S. cannabina using a strain of IRBG74 marked with β-glucuronidase (GUS) and Green Fluorescent Protein (GFP). IRBG74 infected both of the host plants through crack entry under submerged conditions, but showed root hair mediated infection under aerobic …

Identification And Characterization Of Msab Gene Involved In Biofilm Formation And Virulence In Staphylococcus Aureus, Amelsaad Elbarasi

Master's Theses

Staphylococcus aureus is an important human pathogen that causes a wide variety of life-threatening infections ranging from minor skin and oral infections to severe infections, such as bacteremia, pneumonia, osteomyelitis, or endocarditis due to the presence and secretion of a large number of virulence factors that are controlled by global virulence regulators in complex networks. Furthermore, S. aureus infections have become a threat to public health because of their high potential to form biofilm, and their ability to resist a wide range of antibiotics has exacerbated further. Therefore, understanding the regulatory networks and developing a drug targeting these networks has …

Role Of Msaa Gene In Regulation Of The Msaabcr Operon And Biofilm Development In Staphylococcus Aureus, Ahmed Alzuway

Master's Theses

Staphylococcus aureus is an important human pathogen that causes wide variety of diseases ranging from chronic biofilm associated infection to acute life threatening infection such as bacteremia, pneumonia, osteomyelitis, or endocarditis, despite the progress with antibiotics used in the treatment of bacterial infections. Furthermore, increased use of prosthetic and indwelling devices in modern medical practices has led to increased infections due to S. aureus. Treating S. aureus infections have become difficult owing to its ability to resist most of the antibiotics; this problem is further exacerbated by ability of MRSA strains to form biofilms. Emergence of community-acquired methicillin resistance …

Controlling Pseudomonas Aeruginosa Biofilms And Persister Cells By Manipulating Cell-Cell Signaling, Shuyuan Ma

Theses - ALL

Bacterial cells often form sessile biofilms that are up to 1,000 times more resistant to antimicrobial agents than free-living cells. Meanwhile, bacteria produce a small subpopulation of slow-growing or non-growing persister cells that exhibit high tolerance to antibiotics. Both biofilms and persister cells play important roles in the recalcitrance of chronic infections. Recent studies have shown that bacterial cell-to-cell communication, named quorum sensing (QS), is involved in the biofilm and persister formation.

In this study, we investigated the effects of quorum sensing signals N-(3-oxododecanoyl)-homoserine lactone (3-oxo-C12-HSL) and N-butyryl homoserine lactone (C4-HSL) on isolated Pseudomonas aeruginosa PAO1 and PDO300 persister cells. …

Regulation Of Biofilm And Antibiotic-Resistance By The Modulator Of Sara (Msa) In Staphylococcus Aureus, Antony Schwartz

Dissertations

Staphylococcus aureus is an important human pathogen that is the causative agent of life-threatening diseases such as endocarditis and osteomyelitis. The ability of S. aureus to thrive as a successful pathogen can be partially attributed to its ability to form biofilm. Biofilm is an extracellular polysaccharide, protein, and DNA-based slime layer that protects the bacterial community. The global regulator sarA is essential for biofilm formation. Since the modulator of sarA (msa) gene regulates several virulence factors and is required for the full expression of sarA, the capacity of the msa mutant to form a biofilm was examined. The mutation of …

Candida Albicans Adhesion And Biofilm Formation On Phosphated And Non-Phosphate Containing Poly(Methylmethacrylate) Polymers, Kathryn Elizabeth Ryan

Master's Theses (2009 -)

Denture-induced stomatitis is prevalent among prosthesis users, particularly the elderly and institutionalized where it has been estimated to be present in over 60-65% of denture wearers. Treatment of this clinical condition is problematic due to incomplete disinfection of the acrylic surface and rapid microbial re-colonization. Moreover, ingestion or aspiration of pathogens in denture plaque exposes the elderly and immunocompromised to unexpected infections.

Acrylic polymers have generally been used to replace missing teeth and periodontal tissues in edentulous or partially dentate patients. Currently, edentulous adults in the US population are common, with complete edentulism greater than 41% among Americans aged 65 …

Effects Of Biofilm Age And Composition On Oyster Larval Setting, Alaina Hart

Theses and Dissertations

The lack of success in restoring oyster, Crassostrea virginica, populations to Chesapeake Bay and its tributaries has raised many questions about why many restoration efforts have failed. A number of studies have focused on the larval stage of oysters and considered the variables that impact oyster setting behavior in an effort to understand why oyster populations have not recovered. Studies that have examined setting surfaces suggest that biofilms promote oyster larval settlement; however, similar studies with barnacle larvae have found an inhibitory relationship. The present study utilized field-produced biofilms of different ages to determine if natural biofilms inhibit or promote …

The Role Cranberry Proanthocyanidins Play In The Primary Attachment Of Bacteria To Surfaces: Bacillus Cereus Model, Anthony Robert Jones

Biology Dissertations

The development of a proanthocyanidin (PAC) treatment, along with the understanding of its mechanism of action, would provide an alternative method of preventing attachment to and colonization of surfaces by microorganisms, as well as potentially disrupting preexisting biofilms. The purpose of this research is to examine the role a cranberry proanthocyanidin plays in the primary attachment of Bacillus cereus to an abiotic surface. This technology could be employed in food processing plants where a premium is placed on maintaining a sanitized work environment to prevent product contamination. A biofilm assay showed that a surface treated with proanthocyanidins actually promoted rather …