Microbiology Commons^™

Increasing The Nutritional Value Of Canola Meal Via Fungal Bioprocessing, Jason R. Croat

Electronic Theses and Dissertations

The main limitation of meals from canola and other Brassica spp. is the presence of glucosinolates (GLS), which are anti-nutritional and can even be toxic at high ingestion levels. Furthermore, large amounts of GLS can reduce palatability for livestock and thus reduce intake and growth rates. For this reason canola was bred to contain lower levels of GLS (<30 >μmol/g) and erucic acid (< 2%). However, feed inclusion rates are still limited to ~30%, and this reduces the value of canola meal. The goal of this thesis was to optimize a pretreatment and fungal conversion process to enhance the nutritional value of canola meal. Various combinations of physical/chemical pretreatments, fungal cultures, and incubation methods were investigated to metabolize GLS into cell mass, CO2, or other non-toxic components. These treatments also served to hydrolyze canola meal fiber into carbohydrates which were then metabolized by the fungi into single cell protein. Solid-state incubation conditions were initially tested, since filamentous fungi are well adapted to grow at lower moisture levels, and this would potentially reduce contamination issues with bacteria. Flask trials were performed using 50% moisture, hexane extracted (HE) or cold pressed (CP) canola meal, with incubation for 168 h at 30ºC. On HE canola meal Trichoderma reesei (NRRL-3653) achieved the greatest increase in protein content (23%), while having the lowest residual levels of sugar (8% w/w) and GLS (0.4 μM/g). On CP canola meal T. reesei (NRRL-3653), Aureobasidium pullulans (NRRL-58522), and …

Modulation Of The Ovarian Cancer Humoral Response By Tumor-Derived Exosomes., Carolyn Denise Roberson

Electronic Theses and Dissertations

The pathogenesis of epithelial ovarian cancer is complicated by its diagnosis during the latter stages of the disease resulting from lack of symptoms or from presence of symptoms that mimic other conditions. Because of the often fatal prognosis by the time of actual detection, efforts are being made to better understand the host immune response to ovarian cancer. In this study, the contributions of the humoral immune response were investigated by focusing on the role of tumor-derived exosomes and their ability to modulate humoral immune responses. First, ovarian cancer patient-derived free circulating antibodies were investigated for immunoreactivity to patient antigen. …

Modulation Of Host Polyubiquitination By The Ankb F-Box Protein Of Legionella Pneumophila., William M. Bruckert

Electronic Theses and Dissertations

Legionella pneumophila is a facultative intracellular pathogen that infects a wide array of protozoan hosts and human alveolar macrophages. L. pneumophila is dependent on a functional Dot/Icm type IVB secretion system that translocates bacterial effector proteins into the host cell cytosol. L. pneumophila genomes encode more than 250 effector proteins, many of which inhibit host cellular processes to form a favorable niche termed the Legionella-containing vacuole (LCV). The eukaryotic-like Dot/Icm translocated effector AnkB contains two eukaryotic-like ankyrin protein-protein interacting domains, one eukaryotic-like F- box domain and an eukaryotic C-terminal CaaX motif. Immediately following attachment of extracellular bacteria, AnkB is translocated …

A Mechanism For Trif Adaptor-Biased Signaling By Toll-Like Receptor 4., Joseph Peterson Kolb

Electronic Theses and Dissertations

Host cells respond to bacterial lipid A through Toll-like receptor 4 (TLR4). Activation of TLR4 by lipid A triggers a response that involves two main adaptor proteins, MyD88 and TRIF. MyD88-dependent gene expression is associated with proinflammatory protein production, while TRIF-dependent gene expression is essential for optimal activation of adaptive immunity by antigen-presenting cells. Detoxified, monophosphoryl lipid A agonists (MPLA or synthetic MLA) were previously suggested to elicit TRIF-biased TLR4 signaling; that is, induction of weaker MyD88-associated gene expression but relatively intact TRIF-dependent gene expression when compared to fully active diphosphoryl lipid A (lipid A). In this work, we explored …

Il-12 Induced Modulation Of Tumor Derived Myeloid Cell Inflammatory Responsiveness., Courtney Jetun Mitchell

Electronic Theses and Dissertations

Tumor infiltrating and tumor associated myeloid cells (TIMs and TAMs) elaborate an array of factors that promote tumor growth and metastasis. IL-12, a potent inflammatory cytokine has been shown to induce regression of many cancers. We hypothesize that IL-12 augments the ability of TIMs and TAMs to respond to inflammatory stimuli providing a window in which these stimuli are more likely to promote tumor destruction. Related to this hypothesis, we asked two questions: (1) Does IL-12 directly change signaling events associated with inflammatory signal transduction? (2) Is IFN? required for the entirety of IL-12 induced enhancement of the response of …

Probiotic Potential Of Bacterial Isolates From ‘Amabere Amaruranu’ Cultured Milk, Blaise B. Boyiri

Electronic Theses and Dissertations

Probiotics are viable nonpathogenic microbes that positively affect host health. Probiotics inhibit infection, activate immunity, and promote mucosal-barrier development. Many microbes have probiotic activity. Nonetheless, the selection of stable strains and their specific mechanism(s) of action are not fully elucidated. Bacteria from ‘Amabere amaruranu’ cultured milk from Kenya were isolated and identified by PCR sequence analysis of the 16S rRNA gene. Isolates were examined for stability to acid and bile, antimicrobial activity, mucin production, and degradation and sensitivity to antibiotics, hence their potential for probiotics. Lactobacillus isolates were acid unstable, bile-stable, nonmucinolytic, and presented antibacterial activity. L. rhamnosus cell fractions …

Sa-4-1bbl As A Platform To Develop Adjuvant Systems For Prophylactic And Therapeutic Vaccines., Gunes Dinc 1984-

Electronic Theses and Dissertations

Vaccines against infectious diseases are one of the most critical accomplishments in modern medicine. Despite significant progress in vaccinology, there is still a dire need for developing vaccines against various acute and chronic infections and cancer. In general, vaccines are categorized as prophylactic, given to healthy individuals to prevent disease, and therapeutic, administered to people who already have disease. As such, the nature, quality, and quantity of immune responses required for the efficacy of these two types vaccines are different. Prophylactic vaccines against infectious diseases primarily rely on the generation of neutralizing high titers of antibody for their efficacy. These …

Characterization Of Tonb In Rhizobium Leguminosarum Atcc 14479, Brian D. Hill

Electronic Theses and Dissertations

Rhizobium leguminosarum is a gram-negative soil bacterium that requires iron for survival. However, iron becomes insoluble in the presence of oxygen at physiological pH. In response, Rhizobia species have used siderophore mediated iron transport systems to meet their iron requirements. R. leguminosarum ATCC 14479 produces the trihydroxymate siderophore vicibactin and we hypothesize that the import of the ferric iron-vicibactin complex is energized by the TonB-ExbB-ExbD system. Here, we have identified a putative tonB gene. A tonB mutant was created and compared with wild type in its ability to transport ⁵⁵Fe-vicibactin. Also, the putative TonB of R. leguminosarum ATCC …

Regulation Of Macrophage Inflammatory Signaling Pathways By Amp-Activated Protein Kinase., Yanfang Zhu

Electronic Theses and Dissertations

AMP-activated protein kinase, AMPK, is a conserved serine/threonine kinase with a critical function in the regulation of metabolic pathways in eukaryotic cells. Recently, AMPK has been shown to play an additional role as a regulator of inflammatory activity in leukocytes. Treatment of macrophages with chemical AMPK activators, or forced expression of a constitutively active form of AMPK, results in polarization to an antiinflammatory phenotype. Additionally, we reported previously that stimulation of macrophages with antiinflammatory cytokines such as IL-10, IL-4 and TGF-ß results in rapid activation of AMPK, suggesting that AMPK contributes to the suppressive function of these cytokines. In the …

Identification And Characterization Of Genetic Factors Involved In Candida-Bacterial Interactions, Sean J. Fox

Electronic Theses and Dissertations

Throughout existence, fungi and bacteria have long shared ecological niches and thus engage in numerous interactions to mutually enhance survival or antagonistically gain competitive advantages. Of importance to human health are those interactions that involve bacteria with the opportunistic fungi, Candida albicans. An important virulence factor of C. albicans is the ability to control morphology, which allows the transition between yeast, pseudohyphal, and hyphal phenotypes. Morphological control in C. albicans is governed by quorum sensing and the secreted autoregulatory molecule farnesol. Quorum sensing allows individual cells to sense the environment and respond as a group. Bacteria also use quorum …

Investigating Potential Bioactive Compounds From Rhodococcus And Their Effects On Mcf7 Breast Cancer Cells, Megan N. Crabtree

Electronic Theses and Dissertations

Many drugs used in the treatment of various cancers are derived from or influenced by compounds from nature. The soil bacterium Rhodococcus is of interest because of its identified secondary metabolic pathways and the production of novel natural antibiotics from several strains. In this study, a solid agar extraction method was used to collect compounds from strains of Rhodococcus. These bacterial compound extracts were then tested using a MTT assay in order to evaluate their effectiveness in augmenting MCF7 breast cancer cell death. The results of two way ANOVA analyses revealed 18 compound extracts from 15 strains of Rhodococcus that …

Detection Of Bacterial Retroelements Using Genomics, Sen Mu

Electronic Theses and Dissertations

The reverse flow of genetic information can occur when a special DNA polymerase called Reverse Transcriptase (RT) copies the genetic information in an RNA molecule back into a complementary DNA. One type of RT encoding gene found in bacteria is called a retron element. Recent bacterial genome sequencing projects have revealed many examples of retron RT genes. This gene assignment is based on comparison with a few known retron RT proteins. However, RT proteins are highly diverse in their amino acid sequences, and thus the assigned identity of these RT proteins as retrons in genome databases is questionable. One way …

A Mathematical Model For Antibiotic Resistance In A Hospital Setting With A Varying Population, Edward H. Snyder

Electronic Theses and Dissertations

Antibiotic-resistant bacteria(ARB) is causing increased health risk and cost to society. Mathematical models have been developed to study the transmission of resistant bacteria and the efficacy of preventive measures to slow its spread within a hospital setting. The majority of these models have assumed a constant total hospital population with the admission and discharge rates being equal throughout the duration. But a typical hospital population varies from day to day and season to season. In this thesis, we apply variable admission and discharge daily rates to existing deterministic and stochastic models which examine the transmission of single and dual resistant …

Bacterial Assemblages And Microbial Enzyme Activity In The Major Tributaries Of The Lower Mississippi River, Justin Millar

Electronic Theses and Dissertations

Spatial variation in the structure and function of bacterial communities is far more complex than previously believed. High throughput sequencing techniques have begun to elucidate the dynamic worldwide patterns of bacterial biogeography; however, there are still many ecosystems for which there is little to no representative data. Currently there are no high throughput-based analyses of bacterial assemblages in large rivers. Rivers form important connections between terrestrial land use and marine biogeochemistry and act as conduits for organisms and allochthonous nutrients. Bacteria dominate carbon cycling and nutrient processing in rivers, and therefore can influence regional and global elemental cycles. This study …

An Investigation Of Bacterial Ribonucleases As An Antibiotic Target, Ashley Denise Frazier

Electronic Theses and Dissertations

Antibiotics have been commonly used in medical practice for over 40 years. However, the misuse and overuse of current antibiotics is thought to be the primary cause for the increase in antibiotic resistance.

Many current antibiotics target the bacterial ribosome. Antibiotics such as aminoglycosides and macrolides specifically target the 30S or 50S subunits to inhibit bacterial growth. During the assembly of the bacterial ribosome, ribosomal RNA of the 30S and 50S ribosomal subunits is processed by bacterial ribonucleases (RNases). RNases are also involved in the degradation and turnover of this RNA during times of stress, such as the presence of …

Antimicrobial Activity, Cytotoxicity And Phytochemical Analyses Of Rhus Aromatica, Rhus Glabra And Sanguinaria Canadensis Native To South Dakota, Gitanjali Nandakafle

Electronic Theses and Dissertations

A total of twenty five South Dakota native medicinal plants were screened against enterotoxigenic Escherichia coli using a disk diffusion assay. Out of these 25 plants, three plants Rhus aromatica, Rhus glabra and Sanguinaria canadensis demonstrated the highest bacterial inhibition. The minimum inhibitory concentrations (MIC) of these plant extracts were determined using a bacterial enumeration assay. Alamar Blue in vitro cytotoxicity test showed that all extracts have some toxic effect to porcine intestinal epithelial cell lines. Phytochemical analysis of these plant extracts indicated the presence high concentration of flavonoids and condensed tannins in R. aromatica and that R. glabra contained …

Isolation Of A Rhodococcus Soil Bacterium That Produces A Strong Antibacterial Compound., Ralitsa Bogomilova Borisova

Electronic Theses and Dissertations

Rhodococci are notable for their ability to degrade a variety of natural and xenobiotic compounds. Recently, interest in Rhodococcus has increased due to the discovery of a large number of genes for secondary metabolism. Only a few secondary metabolites have been characterized from the rhodococci (including 3 recently described antibiotics). Twenty-four new Rhodococcus strains were isolated from soils in East Tennessee using acetonitrile enrichment culturing and identified using 16S rRNA analysis. Forty-seven Rhodococcus strains were screened for antibiotic production using a growth inhibition assay. One strain, MTM3W5.2, had 90% similarity to the Rhodococcus opacus 16S rRNA gene sequence and produced …

Requirement Of Ssdelseed-Motif Of Escherichia Coli F1FO Atp Synthase In Antimicrobial Peptide Binding., Junior Kom Tayou

Electronic Theses and Dissertations

F₁F_O ATP synthase is a membrane bound enzyme capable of synthesizing and hydrolyzing ATP. Lately, α-helical cationic peptides such as melittin and melittin related peptide (MRP) were shown to inhibit E. coli ATP synthase. The proposed but unconfirmed site of inhibition is βDELSEED-motif formed by the residues 380-386, located at the interface of α/β subunit of ATP synthase. This project was a mutagenic analysis of βDELSEED-motif residues to understand the binding mechanism and mode of action of peptide inhibitors. The study addressed 2 main questions: Are the antibacterial/anticancer effects of these peptides related to their inhibitory action …

Surface Entropy Reduction To Increase The Crystallizability Of The Fab-Rna Complex, Priyadarshini Palaniandy Ravindran

Electronic Theses and Dissertations

Crystallizing RNA has been an imperative facet and a challenging task in the world of RNA research. Assistive methods such as Chaperone Assisted RNA Crystallography (CARC), employing monoclonal antibody fragments (Fabs) as crystallization chaperones have enabled us to obtain RNA crystal structures by increasing the crystal contacts and providing initial phasing information. Using this technology the crystal structure of [delta]C209 P4-P6 RNA (an independent folding domain of the self-splicing Tetrahymena group I intron) complexed to Fab2 (high affinity binding Fab) has been resolved to 1.95 Å (1). Although the complexed class I ligase ribozyme has also been crystallized using CARC …

Discovery And Characterization Of An Antibiotic From The Soil Bacterium Bacillus Sp., Thomas S. Barber

Electronic Theses and Dissertations

Many important antibiotics have become nearly obsolete due to the rise of antibiotic resistant pathogens. Rhodococcus, an actinomycete related to the prolific antibiotic producing genus Streptomyces, harbors over 30 genes for secondary metabolism that could be involved in antibiotic production. Several antibiotics have already been reported for Rhodococcus, suggesting the genus may be a good source for new inhibitory compounds. Fifty four soil bacteria were isolated using enrichment culture techniques (including 37 Rhodococcus) and screened for antibiotic producers. BTHX2, a species of Bacillus was found to have activity against Micrococcus luteus and Rhodococcus erythropolis. BTHX2 …

Modulation Of Alpha-Subunit Visit-Dg Sequence Residues Ser-347, Gly-351 And Thr-349 In The Catalytic Sites Of Escherichia Coli Atp Synthase., Laura Elaine Brudecki

Electronic Theses and Dissertations

Binding of inorganic phosphate (P_i) in ATP synthase catalytic sites is a crucial step for the synthesis of adenosine-5'-triphosphate (ATP). ATP is the fundamental means of cellular energy in almost every organism, and in order to gain insight into the regulation of ATP catalysis, critical amino acid residues responsible for binding P_i must be identified. Here, we investigate the role of highly conserved α-subunit VISIT-DG sequence residues αSer-347, αGly-351, and αThr-349 in P_i binding. Mutations αS347A/Q, αG351Q, αT349A/D/R, βR182A, and αT349R/βR182A were generated via site directed mutagenesis. Results from biochemical assays showed that αSer-347 is required …

Isolation Of A Siderophore Produced By Methicillin-Resistant Staphylococcus Aureus Strain H372., Rachel Elizabeth Presswood

Electronic Theses and Dissertations

Iron is necessary for many cellular processes such as the electron transport chain and gene regulation. However, most iron on earth is found in insoluble iron-hydroxide complexes. In addition, iron is tightly sequestered in the human body by proteins such as transferrin, making it unavailable for pathogens. In order to overcome these limitations bacteria have evolved siderophores. Siderophores are low molecular weight compounds that bind ferric iron with a high affinity. Staphylococcus aureus is an important human pathogen that is known to produce at least four siderophores, and these siderophores contribute to its virulence. S. aureus strain H372 was found …

Inhibition Of Escherichia Coli Atp Synthase By Polyphenols And Their Derivatives., Prasanna Keerthi Dadi

Electronic Theses and Dissertations

We have studied the inhibitory effect of natural and structurally modified polyphenols on Escherichia coli ATP synthase to test (I) if the beneficial dietary effects of polyphenols are related to their inhibitory actions on ATP synthase, (II) if inhibitory effects of polyphenolic compound could be augmented through structural modifications, and (III) if they can act as antimicrobial agent through their actions on ATP synthesis. X-ray crystal structures of polyphenol binding sites suggested that polyphenols bind at a distinct polyphenol binding pocket, at the interface of α,β,γ-subunits. We found that both natural and modified polyphenols inhibit E. coli ATP synthase to …

Isolation And Identification Of The Siderophore "Vicibactin" Produced By Rhizobium Leguminosarum Atcc 14479., William H. Wright Iv

Electronic Theses and Dissertations

Siderophores are small, iron chelating molecules produced by many bacteria to help meet the iron requirements of the cell. Multiple metabolic functions require iron as it serves as a cofactor in many enzymes and cellular processes. However, in the presence of oxygen and at physiologic pH, iron forms insoluble ferric complexes that cause the nutrient to be unavailable to bacterial cells. Siderophores alleviate this limitation by chelating the ferric iron, rendering it soluble and available for uptake. One group of microorganisms known for their ability to produce siderophores is the rhizobia. These bacteria are characterized both by their formation of …

Molecular Mechanism Of Ferricsiderophore Transport Via The Outer Membrane Receptor Fhua In Escherichia Coli., Jennifer K. Cooke

Electronic Theses and Dissertations

Iron is essential for life and growth in most organisms. Although it is abundant, iron exists mostly as insoluble iron-oxyhydroxide. Bacteria secrete siderophores to chelate iron and transport it into the cell via specific outer membrane receptors. The FhuA receptor protein transports ferrichrome, a siderophore produced by Ustilago sphaerogena. We determined the binding affinity of variants from the conserved 'lock region' of FhuA and also created and characterized variants of the highly conserved R452 to determine its role in ferrichrome transport. We hypothesize that during transport the plug domain of FhuA does not leave the barrel; rather it undergoes …

Microscopic Analysis Of Sympathetic And Parasympathetic Distribution, Terminal Morphology, And Interaction In Whole-Mount Atria, Scott Harden

Electronic Theses and Dissertations

The sympathetic (SNS) and parasympathetic (PSNS) branches of the autonomic nervous system (ANS) innervate the heart, exerting excitatory and inhibitory influences (respectively) over cardiac functions (heart rate, AV conduction velocity, and contractility). However, the distribution and structure of SNS and PSNS innervation has not yet been well studied. Detailed characterization of the distributional organization and structural morphology of the SNS and PSNS in normal states is essential to the study of pathological autonomic remodeling. The present study utilized double immunohistochemical labeling techniques to examine tyrosine hydroxylase (TH) immunoreactive (IR) SNS and vesicular acetylcholine transporter (VAChT) IR PSNS axons and terminal …

The Expression Of Mkrn1, An E3 Ubiquitin Ligase For Telomerase Reverse Transcriptase, Is Induced With Differentiation Therapy In Leukemia, Jose Salvatico

Electronic Theses and Dissertations

Telomeres are important structural and functional components of chromosomes, serving to provide stability and enabling full replication of the chromosomes. However, a shortening of the telomeres occurs with each cell division that can be fixed by a polymerase activity provided by telomerase, preventing this loss which would otherwise eventually lead to chromosome end-to-end fusions, senescence and cell death. The telomerase activity is present in stem cells and germ line cells, but absent or barely noticeable in adult somatic cells. However, in approximately 80-90% of transformed somatic cells the telomerase activity is recovered, resulting in a "telomerase positive phenotype". This phenotype …

Structure-Function Analysis Of Endoproteolytic Cleavage: Site-Directed Mutagenesis Studies Of The Α-Msh Cleavage Site In Silurana Tropicalis Pomc, Quinn Kun Chen

Electronic Theses and Dissertations

The maturation process of many prohormone molecules typically requires endoproteolytic cleavage C-terminal of dibasic residues, such as the K¹⁴¹R¹⁴²↓ site N-terminal of the α-melanocyte stimulating hormone (α-MSH) sequence in Silurana tropicalis proopiomelanocortin (POMC). In order to determine the absolute requirement of basic amino acid residues in the cleavage process, site-directed mutagenesis was employed to substitute alanine for the wild-type residues in the frog POMC open reading frame. Specifically, the following underlined residues were individually targeted for alanine substitution: R ¹³⁷ Q ¹³⁸ E ¹³⁹ N ¹⁴⁰ K ¹⁴¹ R ¹⁴²↓. The mouse pancreatic αTC1.9 cell …

Retrocyclin, A Potent Hiv-1 Entry Inhibitor, Nitya Venkataraman

Electronic Theses and Dissertations

Human immununodeficiency virus (HIV) infection is the leading cause of death due to viral infections worldwide. In the absence of an effective vaccine or consistent male condom use, there is a clear need for female-controlled preventatives such as topical vaginal microbicides. Recent attention has been focused on developing natural antimicrobial peptides, as anti-retroviral microbicides. Increasing evidence suggests that cationic antimicrobial peptides such as defensins are effective HIV-1 inhibitors. Human alpha- and beta-defensins contribute substantially to innate immune defenses against microbial and viral infections. Certain nonhuman primates also produce theta-defensins – 18 residue cyclic peptides that are potent HIV-1 entry inhibitors. …

Mcp-1 And App Involvement Of Glial Differentiation And Migration Of Neuroprogenitor Cells, Emmanuel Vrotsos

Electronic Theses and Dissertations

Neuroprogenitor cells are an important resource because of their potential to replace damaged cells in the brain caused by trauma and disease. It is of great importance to better understand which factors influence the differentiation and migration of these cells. Previously it has been reported that neuroprogenitor cells undergoing apoptotic stress have increased levels of Amyloid precursor protein (APP) and increased APP expression results in glial differentiation. APP activity was also shown to be required for staurosporine induced glial differentiation of neuroprogenitor cells. Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is expressed during inflammatory. The binding of MCP-1 to …