Microbiology Commons^™

Genomic And Metabolic Network Properties In Thermophiles And Psychrophiles Compared To Mesophiles, Amal Saeed Alblooshi

Theses

Thermophiles and psychrophiles are extremophilic microorganisms that thrive in harsh conditions. Thermophiles are mostly located in hot springs, prosper in high temperatures. Psychrophiles thrive in extremely cold environments, including polar regions and deep-sea habitats. Although they play a crucial role in biotechnology and environmental research, their mechanisms of adaptation are still not well understood. The main objective of this thesis is to understand the genomic characteristics and metabolic network features in thermophiles and psychrophiles compared to mesophiles. The genomes of 59 species among thermophiles, psychrophiles, and mesophiles were collected from the NCBI database. These genomes were used to analyze their …

Effects Of Vitis Vinifera L. Seed Extract On Short-Term Memory Of Amyloid-Beta-Mediated Neurodegeneration In Transgenic Caenorhabditis Elegans, Elise Patrick

Theses

Alzheimer's disease (AD) is a neurodegenerative condition that is a common cause of dementia and a growing concern worldwide with no effective treatment or cure. Two pathological AD hallmarks include buildup of amyloid beta (Aβ) plaques and neurofibrillary tangles in the brain. Recent attention has turned to exploring natural products and compounds for AD symptom relief and treatment. Vitis vinifera grape seed extract (GSE) contains many beneficial substances. GSE has been tested in several animal models and has shown to improve memory and is even being examined in an AD treatment human clinical trial. In this study, the aim was …

Elucidation Of Potential Antimicrobial Properties Of Chalcones, Caleb Howell

Theses

The rise of antibiotic-resistant bacteria is a growing concern for the medical and biological community. Increased use of antibiotics has led to increased development of bacterial tolerances. This phenomenon, driven by the principles of evolution, has been exacerbated by the improper antibiotic use of these antibiotics. Often, individuals stop taking antibiotics once symptoms subside, mistakenly believing the infection is cured. This practice allows bacteria or fungi to develop resistance.

These antibiotics have been developed from secondary metabolites. While we have many effective antibiotics we are facing new threats. Chalcones are being looked at for their potential in addressing this issue. …

The Anticancer Activity Of A Novel 8-Hydroxyquinoline Derivatives Against 5-Fluorouracil Resistant Colorectal Cancer Cells, Mazoun Talal Al Azzani

Theses

Cancer is a global health crisis for which 20 million new cases were diagnosed in 2022 alone, with 9.3 million cancer-related deaths. Nearly 900,000 deaths were due to colorectal cancer (CRC), which is the third leading cause of cancer related mortality. In the United Arab Emirates, 550 new cases of CRC were reported in 2022. A major clinical challenge with CRC treatment is the development of resistance to 5-fluorouracil (5FU)-based chemotherapy regimens, which are the standard treatment for CRC. In the present study, the anticancer activity of two novel 8-hydroxyquinoline (8-HQ) derivatives AS45 and AS47 was examined against 5FU-sensitive (HCT116) …

Screening And Analysis Of The Urobiome For The Production Of Antimicrobial Peptides To Target Uropathogenic Escherichia Coli, Jennifer Jones

Theses

Urobiome research is currently at a nascent stage, due to a previously incorrect assumption that the bladder is a sterile environment. Improvements in bacterial culturing and DNA sequencing techniques have revealed a diverse resident bacterial community within the urinary tract (urobiome). As global incidences of multidrug- resistant urinary tract infections (UTIs) continue to increase, so too does the demand for novel antimicrobial therapies. Due to its relatively understudied nature, the urobiome represents a reservoir that could be mined as a potential source of novel antimicrobial compounds (e.g., bacteriocins). The aim of this thesis was to identify urobiome bacteriocins that could …

Characterization Of Antimicrobial Properties Of Excrement And Functional Microbiome Of Black Vultures (Coragyps Atratus), Bridgette Gray

Theses

Black vultures, Coragyps atratus, are obligate scavenging birds that consume and dispose of decaying carcasses and carrion. They fulfill a key ecological niche in the environments in which they live. It has been observed that these vultures sometimes excrete bodily waste onto their legs. This adaptive behavior could help aid them in controlling bacteria and other microbes they encounter while stepping into a carcass to eat. This study directly examined the antimicrobial properties of the excrement of black vultures across various bacterial species utilizing a zone of inhibition test and a nematode species utilizing a survival assay. The black vulture …

Screening And Genomic Characterization Of Multi-Drug Resistant (Mdr) Bacteria From Hospital Wastewater, Showq Abdelaziz Abdelaziz

Theses

Antimicrobial resistance poses an imminent global threat to public health, with multidrug-resistant (MDR) bacteria being particularly worrisome due to their resistance to multiple antibiotics. Hospital wastewater has been identified as a potential source of MDR bacteria and antibiotic-resistant genes (ARGs). This study aimed to investigate MDR bacteria's prevalence, diversity, and genomic potential in hospital wastewater samples collected from three different hospitals in the UAE. Samples were processed for culturing antibiotic-resistant bacteria using different HiCrome™ chromogenic media to screen for ESBL-producing, Vancomycin, Carbapenem, colistin, and Methicillin-resistant bacteria. The isolates were characterized using VITEk2 antibiotic profiling and identified using 16S rRNA sequencing …

Characterisation Of Selected Microbes In Terrestrial And Simulated Extraterrestrial Habitats: Human Health And Environmental Applications, Daniel Joseph Keaney

Theses

The rapid development of the Space industry and associated technologies over the past decade is leading to the inevitable consideration of establishing human-based colonies on extra-terrestrial bodies such as the moon and Mars. With Mars being the focus of not only this body of work, but current New Space Age travel (NASA and SpaceX), a significant issue posed by Martian colonists includes establishing a safe and sustainable food source. Owing to its constantly evolving prehistoric landscape, the soils of Mars are contaminated with sodium perchlorate, a water-soluble salt that is toxic to humans, leftover from once inferred brine seeps that …

Correlation Of Gut Alteration With The Progression Of Experimental Autoimmune Encephalomyelitis (Eae) In C57bl/6 Mice, Al Anood Ahmed Al Naqbi

Theses

Background: Experimental autoimmune encephalomyelitis (EAE) is the mouse disease model of multiple sclerosis (MS), a chronic autoimmune disease targeting the central nervous system (CNS) resulting in neuroinflammation, neuroaxonal degeneration, and demyelination. Autoreactive CD4⁺ T cells are known for their role in the pathogenesis of MS. CD8⁺ T cells and NK cells were also found to be associated with the disease.

Aim: There is a limited number of studies investigating the link between gut alterations and immune cells in the gut influencing the outcome of the disease since the vast majority of MS patients experience gastrointestinal (GI) problems. Here, …

Factors Affecting The Antibacterial Activity Of Cefiderocol On Klebsiella Pneumoniae With Diverse Characteristics, Lana Jamal Rashed Daoud

Theses

Antimicrobial resistance (AMR) is a growing serious threat that poses a burden on the healthcare system. Spread of AMR bacteria limits treatment options; thus, new antimicrobial agents are required. Cefiderocol (CFDC) is a novel siderophore cephalosporin, approved by the FDA in 2019 for use in treating infections caused by multi-drug resistant (MDR) pathogens; but it is not yet in clinical use in the UAE. CFDC is equipped with stabilizers against β-lactamases as well as a siderophore side chain that allows it to penetrate the outer membrane of bacteria through the iron uptake pathways. The aim of this study is to …

Mechanistic Insights On The Role Of Ambrisentan, An Endothelin Type-A Receptor Antagonist, In Breast Cancer, Ruba Saleem Lutfi Amer

Theses

The activation of the endothelin receptor type A (ETAR) by its ligand endothelin-1 (ET-1) is well known for its role in vasoconstriction. Interestingly, ET-1 and ETAR are over-expressed in various human tumours, including breast cancer. Several studies described the important role of ETAR in cancer progression and metastasis. The extensive network of interactions that exist between the ET-1 axis and other signalling pathways can trigger autocrine and paracrine signalling that modulates different tumorigenesis processes, such as cellular proliferation and survival, epithelial-to-mesenchymal transition (EMT) and chemoresistance. The main objective of this study was to investigate the antitumor effects of Ambrisentan, a …

Elucidation Of Novel And Established Campylobacter Species With Clinical And Agricultural Significance Through Phenotypic, Genotypic, And Taxonomic Investigation, Caoimhe Lynch

Theses

Campylobacter spp. are well-established human, veterinary and economic pathogens, with a broad host range spanning from terrestrial and marine mammalian, avian and reptilian hosts. The scope of the study includes novel and notorious species within the genus, with reference to zoonotic agents Campylobacter jejuni and Campylobacter coli - the leading cause of human bacterial gastroenteritis in the EU and Ireland, Campylobacter fetus that represents the most common campylobacter causing bacteraemia and two novel species isolated from pigs not described in the literature previously. C. jejuni and C. coli isolates (n = 350) recovered from broiler caecal and neck skin samples, …

Predicting, Monitoring And Controlling The Growth Of Listeria In Complex Food Matrices, Laura Mary Nyhan

Theses

Listeria monocytogenes is a foodborne pathogen which is a significant challenge in food production, particularly for ready-to-eat (RTE) products. Incidence of Listeria in RTE foods can be reduced by the application of intelligent combinations of preservative factors or hurdles, while data quantifying the efficacy of hurdle combinations can be exploited and used in the area of predictive microbiology. Traditional culture-based techniques, such as viable plate counts, are commonly used to monitor the growth/survival of microorganisms in foods, however these methods are tedious, time-consuming and due to their destructive nature, are associated with low reproducibility and high variability. Therefore, rapid, non-invasive …

Comparison Of The Effects Of Land Use / Land Cover On Water Quality And The Intertidal Marine Macroalgae Communities At The Fluvial Outflows Of The Dingle Peninsula, Cassandra Lew

Theses

The Milltown, Feohanagh, and Owenmore river basins located on the Dingle Peninsula in Ireland were studied to see how variation in land use and land cover (LU/LC) affected water quality and the macroalgal communities at each river’s respective fluvial outflow. Abundance and composition of macroalgae in river and coastal water bodies have been designated as an indicator of water quality according to the Water Framework Directive 2000. The results of this study found that the Feohanagh’s macroalgal community had the highest species richness for most months while the Milltown had the highest Shannon Diversity Index. The Owenmore’s community was consistently …

Group B Streptococcus: Molecular Epidemiology, Pathogenic Profiling And Control Strategies, Katherine Mary Hayes

Theses

Group B Streptococcus (GBS) are frequent colonisers of the gastrointestinal tract of healthy adults with worldwide rates of 18% colonisation; however, they are also opportunistic pathogens capable of causing invasive disease, particularly in neonates and adults with underlying conditions. Indeed, GBS is the leading cause of invasive neonatal disease worldwide with a global incidence of 0.49 per 1000 live births and GBS disease in adults is increasing globally, with estimated rates of 10.9 cases per 100,000 people. While GBS remain largely susceptible to penicillin, there have been reports of reduced beta-lactam susceptibility in certain countries and resistance to other antibiotic …

Crystallographic Studies On Host-Interacting Proteins Of Phage K Virion, Antonio Pichel Beleiro

Theses

Phage K is a lytic bacteriophage that infects a broad range of staphylococci, including some methicillin-resistant Staphylococcus aureus strains. Phage K attaches to its host via a baseplate. The contracted conformation of the baseplate contains a fiber and two receptorbinding proteins responsible for the interaction with the host. The native conformation of the baseplate also includes a tail central spike that shears off after contraction. The aim of the thesis is the structural characterization of phage K receptor-binding proteins and tail central spike. Experimentally, the thesis relies on crystallographic methods, which encompass: production of suitable sample, crystallization, diffraction, and data …

The Occurrence Of Listeria Monocytogenes In The Mushroom Production Chain And The Use Of Bacteriophage For Its Control, Vincenzo Pennone

Theses

In Agaricus bisporus production, the occurrence of L. monocytogenes is still poorly understood. A number of studies have shown the presence of L. monocytogenes in the mushroom processing environment, suggesting its source from raw materials storage areas (Viswanath et al, 2013; Murugesan et al, 2015). In this study, 10 mushroom producers and three raw material (compost and casing) producers participated in two surveys on the occurrence of L. monocytogenes in the most high-risk areas of the production environment. In the first survey, floors, drains, platforms, crates, raw materials and mushrooms were tested for L. monocytogenes presence and the results were …

Crystallographic Structure Determination Of Bacteriophage-Encoded Enzymes That Specifically Target Pathogenic Bacteria, Marta Sanz Gaitero

Theses

Antibiotic resistance is becoming a serious public health concern. Infections that some decades ago could be treated with antibiotics now sometimes do not respond to traditional treatment, causing higher mortality and economic losses. An alternative to the use of antibiotics are bacteria's natural predators, bacteriophages (or phages), and specifically their lytic enzymes. These proteins are produced by phages to degrade bacterial peptidoglycan to inject their genetic material into the bacteria (virion-associated peptidoglycan hydrolases) or to release their progeny once the infection is finished (endolysins). They can be applied exogenously to lyse Gram-positive bacteria or be genetically engineered to lyse Gram-negative …

Microbiota, Diet And Medication In Human Gut Disorders, Adam Clooney

Theses

The microbiota, a community of micro-organisms in a particular environment, have been intensely researched in the past decade and interest appears to continue to increase. The human body is richly populated with bacterial cells (3.8x10'^) and alterations in these communities are associated with disease. The work presented in this thesis explores aspects of microbiota research methodologies with regard to optimisation and concerns over a lack of reproducibility. Additionally, we investigated the effects of medication, in particular Proton Pump Inhibitors, on the human gut microbiota, along with comparisons between the microbiota of patients with active and inactive Inflammatory Bowel Disease.

Microbiota …

A Diagnostic And Control Programme For Johne’S Disease On Irish Dairy Farms, Aideen Kennedy

Theses

Johne’s disease (JD) is an enteritis of ruminants with potential zoonotic implications. JD diagnosis and control present difficulties given JDs prolonged subclinical nature. In order to improve JD control in Ireland, PhD aims included conducting a national survey documenting high-risk husbandry practices employed on Irish farms, thereby targeting areas for improved management. Furthermore as JD has been associated with on-farm economic losses internationally, this research programme aimed to analyse production losses associated with testing JD ELISA positive on Irish dairy farms. A longitudinal study was also conducted to assess if successful JD control can be achieved using gold-standard protocols. Due …

The Development Of New Molecular Tools To Detect Mycobacterium Avium Subspecies Paratuberculosis From A Bovine Faecal Environment By Real-Time Pcr, Marcel De Kruijf

Theses

The slow-growing intracellular pathogen Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease in domesticated and wild ruminants. Johne’s disease inflicts severe annual economic losses to the dairy industry worldwide. This thesis is divided into five chapters that consist of a literature review' chapter and four experimental chapters focusing on MAP strain genotyping and the development of novel molecular MAP detection tools using real-time PCR. Chapter 1 describes published information regarding MAP characteristics, Johne’s disease, MAP genomes, available MAP detection methods, MAP epidemiology and genotyping.

To efficiently control and monitor MAP infection, molecular t>ping of MAP strains provides extensive knowledge …

Mycobacterium Species Identification In An Acute Hospital: Towards Rapid Identification, And Improved Epidemiology, Using Novel Mass Spectrometry Analysis, James Anthony O'Connor

Theses

Mycobacteria are a heterogeneous group of bacteria that cause a wide spectrum of disease, including Tuberculosis (TB), the single biggest killer worldwide. The genus also incorporates over 170 nontuberculosis (NTM) species, many of which are opportunistic pathogens. The aim of this project was to ascertain the burden of mycobacterial disease in the region and to determine the efficacy of Matrix-Assisted Laser Desorption/Ionisation time-of-flight (MALDI-tof) mass spectrometry (MS) for novel uses as a rapid identification method for clinical mycobacteria and as a typing tool for Mycobacterium tuberculosis complex isolates. A five-year retrospective epidemiological study of the region was conducted, the first …

Metabolic Characteristics Of Macrophage Activation With Phenotype Microarrays, Tanya Kathryn D'Souza

Theses

Inflammation is a natural protective response and is characterised by the activation of numerous immune cells, including macrophages which can release a variety of inflammatory mediators. Macrophages play a flexible role in the initiation and effector phases of the immune response and change their behaviour to respond to environmental stimuli. The main objectives in this study were to create and characterise different macrophage behaviours and employ a novel metabolic characterisation platform the Phenotype Microarray^TM to attribute additional characteristics to the currently well recognised phenotypes. Five activated macrophage states were demonstrated and characterised. Unactivated macrophages (MO) demonstrated undetectable levels of …

Prevalence And Distribution Of Gastrointestinal Nematode Parasites And Dung Beetles Associated With Upland And Lowland Grazing Of Irish Native Dexter Cattle, Noel Dineen

Theses

Diseases such as parasitic gastroenteritis are very common in cattle and can have detrimental economic consequences on agricultural productivity. This study was conducted to establish the prevalence and distribution of gastrointestinal nematode parasites associated with Dexter cattle under an organic lowland grazing regime and an extensive upland system. A secondary aim to the study was to investigate dung beetle assemblages in upland and lowland sites and their interactions with gastrointestinal nematode parasites as they offer an alternative method of natural control to organic farming systems in particular.

Cattle weights were recorded and faecal samples were collected at the beginning and …

Clinical Coagulase-Negative Staphylococci; Identification, Characterisation And Treatment, Emma Gabriel

Theses

The work presented in this thesis focuses on clinically significant staphylococci (with an emphasis on coagulase-negative staphylococci) in terms of their isolation, identification, characterisation, and biocontrol.

CoNS are increasingly being recognised as true nosocomial pathogens yet remain under-characterised, particularly from an Irish clinical perspective. We examined a large cohort of clinically-derived CoNS, isolated from blood (n=l35), identifying them to species level. Extensive antibiotic resistance against nine clinically-relevant antibiotics was recorded. Additionally, widespread biofilm forming capabilities associated with increased virulence was detected both phenotypically and genotypically. We identified multiple species of CoNS in circulation in an Irish healthcare setting, and determined …

An Investigation Of The Use Of Natural Agents To Control Mycobacteria, Olga Lesniak

Theses

Economic losses that are caused by Mycobacterium avium paratuberculosis (MAP) infections represent a major obstacle for farmers and also for the dairy industry. In order to control the population of MAP, alternative control agents must be investigated. One of the studies described in this thesis focused on using a bacteriophage therapy based approach to assess its efficacy on simulated industrial environments and food models. Another study described in this thesis investigated the antimicrobial effects of parsley and garlic on a range of mycobacteria species. Both studies used conventional microbiological methods such as plaque assays, AlamarBlue assay (MABA) and growth curves, …

Molecular Targets Of Manuka Honey In Human Breast Cancer, Sarah Saif Al Qubaisi

Theses

The medicinal properties of Manuka honey have been extensively studied, particularly in terms of its wound healing and antimicrobial activities. We have previously demonstrated that Manuka honey also has anti-cancer properties against a variety of cancer cell types in vitro as well as in preclinical cancer models. The cellular targets of the anti-cancer activity of Manuka honey, however, remain unknown. For the present study, we selected the triple negative human breast cancer cell line, MDA-MB-231, to investigate susceptibility to Manuka honey and to identify the potential signaling pathways affected. MDA-MB-231 cancer cells are known to constitutively express activated STAT3 transcription …

Induction Of Anti-Microbial Immune Responses In Severely Immunodeficient Hosts By Ifn-Expressing Salmonella Enterica Serovar Typhimurium Correlates With Efficient Activation Of Macrophage Effectors, Mohammed Achraf Al-Sbiei This

Theses

Susceptibility to infection by the intracellular bacterial pathogen, Salmonella enterica serovar Typhimurium (S. typhimurium), is controlled by many genes of innate and adaptive immunity. One of the most critical genes is IFN- and mice deficient in IFN- synthesis are highly susceptible to Salmonella. Previously, we demonstrated that mice deficient in MyD88, an adaptor that regulates TLR signaling, are susceptible to Salmonella infection. In the current study, we compared immune responses in mice deficient in IFN- or MyD88 with wild-type controls following infection with an attenuated strain of S. typhimurium (designated BRD509E) or a recombinant derivative engineered to express murine IFN- …

Characterisation And Applications Of Natural Lactic Acid Bacteria With Emphasis On Weissella Cibaria And Associated Exopolysaccharide, Kieran M. Lynch

Theses

The work presented in this thesis characterises natural cereal-derived lactic acid bacteria and examines their potential application in the dairy fermentation area, with special emphasis on the sourdough isolate, Weissella cibaria MGl and its associated glucan homoexopolysaccharide. This strain is notable for its high-level production of dextran, being termed a “hyper-producef’. Genome sequencing and analysis of a number of IV. cibaria strains was performed in the context of available genomic data for other Weissella species, with special focus on the metabolic traits of W. cibaria MGl, and the results represent the first study to explore members of the Weissella genus …

Exploiting Bacteriophages And Associated Peptidoglycan Hydrolases With Potential For Biocontrol In Food Related Applications, Lorraine Endersen

Theses

The work presented in this thesis describes the isolation and characterisation of novel bacteriophages, and the subsequent exploitation of their bactericidal properties against two opportunistic food related pathogens, Mycobacterium avium subsp. paratuberculosis (MAP) and Cronobacter sakazakii.

MAP is a proven animal pathogen known to cause Johne’s disease in cattle but has been implicated as a causative agent of Crohn’s disease in humans. Despite the fact that this association has yet to be proven, significant focus has been directed towards evaluating the consequences of consuming milk contaminated with MAP. Accordingly, six mycobacteriophages were isolated and characterised in terms of temperature and …