Microbiology Commons^™

The Effects Of Electrostatic Spraying With Organic Acids In The Disintegration Of Biofilms Formed By E.Coli O157:H7 And Salmonella Typhimurium On Spinach And Cantaloupe, Ahmad Almasoud

Graduate Theses and Dissertations

Outbreaks from the consumption of fresh produce are a concern in the United States. The consumptions of fresh produce have increased recently which expose a large segment of society to such outbreaks. Spinach and cantaloupe are minimally heated or processed before consumption which makes them a possible source of foodborne illness. The objective of this research was to investigate the effect of organic acids alone and in combination to reduce attached Salmonella Typhimurium (S.T) and Escherichia coli O157:H7 (E.coli) on spinach and cantaloupe, and to disintegrate biofilm formed by these pathogens by electrostatically spraying with two organic acids. To quantify …

Understanding The Evolution Of Aggregative Multicellularity: A Molecular Phylogenetic Study Of The Cellular Slime Mold Genera Sorodiplophrys And Pocheina, Alexander Tice

Graduate Theses and Dissertations

Cellular slime molds are amoeboid protists that have a unicellular trophic phase and multicellular dispersal stage formed through the aggregation of individuals in their life cycles. These organisms were once thought to form a monophyletic group in the Mycetozoa. After careful morphological, ultrastructural, and molecular studies, cellular slime molds are now thought to be distantly related organisms that have all converged on the cellular slime mold habit. The following thesis consists of two molecular phylogenetic studies on two named genera of cellular slime mold for which little or no molecular data were publically available. In the first study, gene sequence …

Evaluation Of Tulane Virus As A Surrogate For The Study Of Human Norovirus, Sabastine Eugene Arthur

Graduate Theses and Dissertations

Among all known causes of acute gastroenteritis, human noroviruses (HuNoV) are the primary cause (68%) of outbreaks and are associated with 78% of illnesses, 46% of hospitalizations, and 86% of deaths. The main obstacle to studying the pathogenesis of HuNoV is the lack of cell culture system and small animal model. Murine norovirus (MNV) and feline calicivirus (FCV) have been utilized as model surrogate viruses to study HuNoV. In this research, a more recent surrogate virus, Tulane virus (TV), was evaluated for physicochemical stability and environmental persistence. The primary goal was to determine the suitability of TV as a surrogate …

Management Of A Primordial Problem: Redox-Sensitive Transcriptional Regulation In Methanosarcina Acetivorans, Ryan Christopher Sheehan

Graduate Theses and Dissertations

The primordial Earth which hosted the first forms of life was an environment free of oxygen. Early organisms utilized metabolisms dependent upon anaerobic conditions and incorporated systems to which oxygen is deleterious. As the content of oxygen in Earth's atmosphere increased, anaerobic organisms had to acquire methods to sense and combat oxygen and reactive oxygen species. Several mechanisms were advantageous to such anaerobic organisms which correlated transcriptional processes with the redox state of the cell so that energy may be conserved and oxygen stress recovery genes activated during periods of oxidative stress. Iron sulfur (Fe-S) cluster cofactors incorporated within RNA …

A Phylogenetic Analysis Of Dictyostelium Purpureum Based On Nuclear Rdna Sequences, Mahmoud Suliman

Graduate Theses and Dissertations

Dictyostelids (cellular slime molds) are eukaryotic microorganisms that have both unicellular and multicellular stages during their life cycle. In this study, a molecular phylogenetic analysis was conducted for isolates of one species (Dictyostelium purpureum) based DNA sequences of the ITS, 5.8S and SSU regions of nuclear rDNA. Moreover, a detailed morphological study was carried out using images obtained with both dissecting and compound microscopes. Mating experiments were carried out to assess macrocysts formation between each pair of isolates. The constructed molecular phylogenetic trees indicate that (1) D. purpureum isolates are more closely related to each other than to other species …

Methane Emissions From Direct-Seeded, Delayed-Flood Rice Grown On A Clay Soil, Alden Daniel Smartt

Graduate Theses and Dissertations

Due to the production of methane (CH4) under flooded-soil conditions, rice (Oryza sativa L.) cultivation is a major contributor to agricultural CH4 emissions. Studies examining CH4 emissions from rice have only recently been initiated in Arkansas and no data have been collected from rice produced on clay soils in Arkansas. Therefore, research was conducted in 2012 and 2013 at the Northeast Research and Extension Center in Keiser, Arkansas to examine the factors affecting CH4 emissions from rice produced on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts). The objectives of this study were to determine: 1) the effect of vegetation …

Microbial Community Shifts Caused By Changes In The Primary Oxidant At A Drinking Water Treatment Plant, Connie Marie Moloney

Graduate Theses and Dissertations

Microbial communities resistant to common oxidants can cause concerns for water treatment plants (WTPs). If a bacterium is not fully oxidized during disinfection, these species can impede upon filtration processes or seed biofilms in the distribution system. In an effort to minimize disinfection by-products (DBP's) that result from the reaction of chlorine (Cl2) with natural organic matter, water treatment plants have the option to change their primary oxidant to chlorine dioxide (ClO2). The following study examines the change in microbial communities during the sedimentation process under differing oxidation regimes, specifically chlorine (Cl2) and ClO2 at the local water treatment plant …

The Phenotypic Effects And Transcript Response Of Salt Stress, The Impact Of Viral Infection On Salt Stress Symptoms, And The Effect Of Salt Stress On Soybean Virus Vector Activity In Soybean Varieties That Vary In Chloride Uptake, Alma Glenn Laney

Graduate Theses and Dissertations

With the increase in saline soils worldwide, understanding the mechanisms for salt tolerance in plants is important to reduce yield loss due to salt stress. Soybean, Glycine max (L.) Merr., genotypes differ in chloride uptake with genotypes that take up chloride into foliar tissues tending to be salt-sensitive whereas those that partially exclude chloride from the leaves are more salt-tolerant. Transcriptional and physiological responses were measured in two soybean cultivars, Clark and Manokin, which differ in chloride uptake in response to salt stress and in combination with Soybean mosaic virus (SMV) and its aphid vector, Aphis glycines . The interaction …

Enhancement Of Antimicrobial Activity Of Naturally Occuring Phenolic Compounds By Nano-Particle Mediated Delivery Against Listeria Monocytogenes, Escherichia Coli O157:H7, And Salmonella Typhimurium, Madhuram Ravichandran

Graduate Theses and Dissertations

Food-borne illnesses are of major concern in the U.S. and worldwide. Salmonella,Listeria,E. coli O157:H7 continue to be some of the major foodborne pathogens. Recurring recalls due to these pathogens demand critical antimicrobial strategies to decontaminate the food through its procession from farm to fork. In our study, we combined the effectiveness of naturally occurring phenolic compounds individually, with/ without ethylenediamine tetraacetic acid (EDTA) and/or Nisin and nanoparticle delivery to improve the antimicrobial potential of the compounds against Listeria monocytogenes (L.m.), Salmonella Typhimurium (S.T.), and Escherichia coli O157:H7 (E.c.), in brain …

Effects Of Water Column P-Availability And Litter Microbial Mediated Processes And Stoichiometry In Aquatic Systems, Ayla Smartt

Graduate Theses and Dissertations

Anthropogenic nutrient enrichment of aquatic ecosystems is prevalent and can have detrimental effects on biological condition. Many of these effects have been attributed directly or indirectly to changes in autotrophic processes. However, in detrital-based streams changes in course detrital stoichiometry and decomposition have been related to changes community structure and production at higher trophic levels highlighting the importance of considering the heterotrophic microbial responses to enrichment. Leaf litter stoichiometry, which is determined in part by the tree species source and the microbial communities that comprise the associated biofilm, is likely related to decomposition rates, but few studies examine these variables …

A Portable Impedance Biosensing System Based On A Laptop With Labview For Rapid Detection Of Avian Influenza Virus, Yixiang Wang

Graduate Theses and Dissertations

Avian Influenza Virus (AIV) H5N1 is a highly pathogenic virus found not only in birds but also in human. Rapid and sensitive detection method is needed to help prevent the spread of AIV H5N1. In this study, a portable impedance biosensing system based on a laptop with LabVIEW software was developed for detection of AIV H5N1. First, a virtual instrument was programmed with LabVIEW software to form a platform for impedance measurement, data processing and control. The audio card of a laptop was used as a function generator while a data acquisition card was used with the signal channels for …

Antibacterial Activity Of Commercially Available Plant Extracts On Selected Campylobacter Jejuni Strains, Divya Oppath Sivasankaran

Graduate Theses and Dissertations

Campylobacter jejuni is recognized as a leading cause of foodborne illness worldwide with approximately 850,000 cases per year in the United Sates. A total of 18 species of Campylobacter have been identified worldwide to date. Foodborne transmission of C. jejuni is mainly through the consumption of unpasteurized milk, contaminated poultry meat and water. C. jejuni can survive in very diverse environments under stressful conditions in human and animals which is different from the specific conditions and media required in laboratory experiments. There has been increased research in recent years to identify naturally occurring antibacterial agents to control and eliminate C. …

Impedance Biosensors For The Rapid Detection Of Viral And Bacterial Pathogens Using Avian Influenza Virus Subtypes H5n1 And H7n2 And Escherichia Coli O157:H7 As Model Targets, Jacob David Lum

Graduate Theses and Dissertations

This research investigated impedance biosensors for the rapid detection of viral and bacterial pathogens using avian influenza virus (AIV) subtypes H5N1 and H7N2 and Escherichia coli O157:H7 as the model targets, which were chosen due to their impact on the agricultural and food industries. For the detection of AIV H7N2, a single stranded DNA aptamer was selected using systematic evolution of ligands by exponential enrichment (SELEX). The selected aptamer and a previously selected aptamer against AIV H5N1 were used in a microfluidics chip with an embedded interdigitated array microelectrode to fabricate an impedance biosensor for specific detection of AIV H7N2 …

Poultry Performance And Food Safety Impacts Of Selected Organic Acids And Probiotics, Anita Menconi

Graduate Theses and Dissertations

Improving production parameters and controlling foodborne pathogens have been challenges to the poultry industry. Salmonella has been the most common bacterial pathogen in laboratory confirmed foodborne illness cases, and contaminated poultry and poultry products have been identified as the most important source of transmission of Salmonella to humans. Therefore, research on effective interventions to reduce Salmonella transmission at the poultry production level has gained attention. Initially, a series of studies was conducted to evaluate the use of selected organic acids in controlling foodborne pathogens and improving poultry performance. Then, the characterization and application of lactic acid bacteria and Bacillus spp. …

Comparing Virus Ultrafiltration Of Bacteriophages With Filtration Of Minute Virus Of Mice, Kent Smith

Graduate Theses and Dissertations

Industrial production of protein therapeutics demand rigorous testing and clearance of viruses. The U.S. Food and Drug Administration dictate the purity of pharmaceuticals with regards to viral contamination. As this testing is time consuming and expensive using mammalian cells and viruses, bacteriophages may provide a faster and cheaper alternative for membrane filtration processes. We used ultrafiltration membranes to filter protein solutions with viruses. Two bacteriophages were tested against membranes with two different pore sizes. These membranes were then tested by inverting the membrane's orientation. Flux measurements and log virus removal data were taken. Flux and log virus removal were seen …

Bacterially-Mediated Formation Of Rock Coatings In Kärkevagge, Swedish Lapland: A Mineralogical And Micro-Environmental Analog For Mars, Cassandra L. Marnocha

Graduate Theses and Dissertations

The search for past or present life on Mars is, for now, limited to surface environments. An often neglected surface environment that could have served as an abode for life and could presently preserve evidence of that life is that of rock coatings. Rock coatings are mineral accretions on rock surfaces. On Earth, they are widespread and occur with considerable chemical diversity. There is growing evidence for a biotic role in their formation on Earth, particularly with respect to rock varnish. As a result, rock varnish has become a target of astrobiological interest on Mars, where varnish-like coatings have been …

Effects Of Environmental Factors And Nutrient Availability On The Biochemical Composition Of Algae For Biofuels Production: A Review, Ankita Juneja, Ruben Michael Ceballos, Ganti S. Murthy

Biological Sciences Faculty Publications and Presentations

Due to significant lipid and carbohydrate production as well as other useful properties such as high production of useful biomolecular substrates (e.g., lipids) and the ability to grow using non-potable water sources, algae are being explored as a potential high-yield feedstock for biofuels production. In both natural and engineered systems, algae can be exposed to a variety of environmental conditions that affect growth rate and cellular composition. With respect to the latter, the amount of carbon fixed in lipids and carbohydrates (e.g., starch) is highly influenced by environmental factors and nutrient availability. Understanding synergistic interactions between multiple environmental variables and …

Qcm Aptasensor For Rapid And Specific Detection Of Avian Influenza Virus, Luke Brockman

Graduate Theses and Dissertations

There has been a need for rapid detection of avian influenza virus (AIV) H5N1 due to it being a potential pandemic threat. Most of the current methods, including culture isolation and PCR, are very sensitive and specific but require specialized laboratories and trained personnel in order to complete the tests and are time-consuming. The goal of this study was to design a biosensor that would be able to rapidly detect AIV H5N1 using aptamers as biosensing material and a quartz crystal microbalance (QCM) for transducing method. Specific DNA aptamers against AIV H5N1 were immobilized, through biotin and streptavidin conjugation, onto …

Development Of A Predictive Modeling System For Validation Of The Cumulative Mirobial Inactivation Of The Salmonellae In Pepperoni Utilizing A Non-Pathogenic Surrogate Microorganism (Enterococcus Faecalis), Scott Donald Stillwell

Graduate Theses and Dissertations

Salmonellosis is the most frequently occurring bacterial foodborne illness in the United States and the human case rate has not improved for the past two decades. The federal agency responsible for oversight of meat and poultry processors has announced the intent to extend existing pathogen reduction performance standards for Salmonella spp. to cover all classes of products including fermented sausages that are currently produced under HACCP plans that are validated for control of Escherichia coli O157:H7. The proposed regulatory modifications will require processors to revalidate HACCP plan controls to achieve either a 6.5 or a 7.0 log10 inactivation of the …

Proteomic Studies Of The Influenza Virus-Human Cell Interactions: The Responses Of Host Cell Protein Expression To Viral Infection And The Novel Host Proteins That Interact With Virus Protein Ns1, Yimeng Wang

Graduate Theses and Dissertations

Influenza A viruses (IAVs) continue to be a threat to human health. Despite extensive studies, the mechanisms underlying the IAVs-host interactions during IAV infection remain elusive. We employed quantitative proteomic methods to systematically explore the host cell protein expression responses to IAV infection and examine the function of a critical IAV protein called NS1 by identifying its host binding partners. Specifically, we used a 2-dimentional gel electrophoresis (2-DE) based proteomic method to screen host proteins whose expression was substantially altered by IAV. One critical protein named IκB kinase-gamma (IKKγ) was found to be significantly down-regulated during IAV infection. Functional studies …

Litter Conditioning Is Differentially Affected By Leaf Species, Phosphorus Enrichment, And Light Availability, Erin E. Scott

Graduate Theses and Dissertations

Anthropogenic enrichment of nitrogen and phosphorus is one of the most pervasive and detrimental threats to aquatic ecosystems worldwide. In streams that rely on allochthonous basal food resources, such as leaves, nutrient pollution can result in altered food quality and decreased carbon (C) standing stocks. However, the magnitude and mechanisms of this change in quality are poorly understood. Laboratory microcosm studies were conducted to 1) quantify the response of litter C:P to a gradient of phosphorus (P) enrichment (0, 0.05, and 0.5 mg SRP/L) across leaf species with variable levels of degradability (sugar maple and oak), and 2) quantify the …

Cell Bioenergetics In Leghorn Male Hepatoma Cells And Immortalized Chicken Liver Cells In Response To 4-Hydroxynonenal Induced Oxidative Stress, Alissa Laura Piekarski

Graduate Theses and Dissertations

Bioenergetic mechanisms responsible for ATP production are essential in carrying out maintenance and cell-specific functions. In this study, hepatocytes (liver cells) were used to test both endogenous and exogenous stress on cellular respiration. The secondary lipid peroxide, 4-hydroxynonenal (HNE), was used because it alters bioenergetics by increasing mitochondrial proton leak that attenuates mitochondrial radical production and, therefore, endogenous oxidative stress. The major objective of this study was to demonstrate effects of HNE-induced oxidative stress on avian hepatocyte bioenergetics. Various chemical which help enable the determination of oxygen (O2) consumption linked to ATP synthesis (oligomycin), maximal O2 consumption (FCCP), and proton …

The Use Of Diatoms To Infer Environmental Change Of The Lower White River, Southeastern Arkansas, Ruchi Bhattacharya

Graduate Theses and Dissertations

This dissertation describes the limnology of the lower White River oxbow lakes in southeast Arkansas, inundated by the major 2008 spring flood. The flood water and sediment deposited in oxbow lakes were analyzed for water chemistry, sediment geochemistry and diatom assemblages and used as an analogue for past floods. The 2008 spring flood inundated and homogenized the entire floodplain; also represented by the predominantly planktonic diatom assemblage suggesting riverine input. Indicator species for eutrophication were also recorded consistent with the high nutrient content in the lakes. However, the variance in the surface diatom assemblage was best explained by the lake …

Utilization Of Natural Green Tea And Grape Seed Extracts And Nisin To Reduce Conventional Chemical Preservatives And To Inhibit The The Growth Of Listeria Monocytogenes In Ready To Eat Low And High Fat Chicken And Turkey Hotdogs, Amara Venkata Sunil Perumalla

Graduate Theses and Dissertations

Ready-to-eat meat (RTE) products such as hotdogs represent a popular segment in convenience food purchases. Increased demand has led the processors to extend the shelf life by minimizing lipid oxidation and post-processing contaminants such as Listeria monocytogenes. There is a growing interest in the food processors and consumers regarding the use of natural alternatives in place of synthetic food additives to control the growth of foodborne pathogens and (or) lipid oxidation. In recent years, green tea (GTE) and grape seed extracts (GSE) are increasing choices as they have demonstrated antioxidant as well as antimicrobial properties in various food applications. …

Role Of Lactic Acid Bacteria As A Bio-Sanitizer To Prevent Attachment Of Listeria Monocytogenes On Deli Slicer Contact Surfaces, And The Influence Of Listeria Innocua On The Attachment Of L. Monocytogenes On Selected Materials Located In The Food-Processing Environment, Jean Baptiste Ndahetuye

Graduate Theses and Dissertations

Listeria monocytogenes an important foodborne pathogen that continues to be a serious problem for the food industry. This pathogen contaminates food primarily during post-harvest in the food-processing environment. Its ecology in the food-processing environment is not well understood but previous research has demonstrated the ability of L. monocytogenes to survive on food contact surfaces after cleaning and disinfection. The current study explored the attachment of three lactic acid bacteria (LAB) strains, Lactobacillus animalis , Lb. amylovorus and Pediococcus acidilactici , their combination in a cocktail, and their influence to prevent the attachment of L. monocytogenes at room temperature by examining …

Genome-Wide Identification Of Conditionally Essential Genes In Salmonella Typhimurium Using Tn-Seq Method, Anita Khatiwara

Graduate Theses and Dissertations

ABSTRACT

As more whole genome sequences become available, there is an increasing need for high-throughput methods that link genes to phenotypes and facilitate discovery of new gene functions. The objective of this study was to develop a high-throughput method to study gene functions in bacteria and use this method to study gene functions of S. enterica serotype Typhimurium (S. Typhimurium) under various environmental conditions encountered during its life cycle. Chapter I of this dissertation reviews the history and evolution of functional genomics in bacteria with focus on Salmonella, along with the recent techniques available. Chapter II, deals with the development …

In Vitro Selection Of Aptamers Against Avian Influenza Virus H5n1, Jingjing Zhao

Graduate Theses and Dissertations

Over $10 billion losses in the poultry industry were caused by avian influenza (AI) so far. Rapid and specific detection of avian influenza virus is urgently needed with the concerns over the outbreaks of highly pathogenic H5N1 influenza virus and cases of animal and human infection. Aptamers are oligonucleic acid or peptide molecules that bind a specific target molecule with good affinity. They show better thermal stability than antibodies. The goal of this research was to select DNA-aptamers as the specific recognition element of AI H5N1virus to be used in detection assays specific for field application. In this study, Systematic …

Detection Of Two Pathogens Of High Importance To The National Poultry Improvement Plan: Salmonella Spp. And Mycoplasma Spp., Robin Levi Jarquin

Graduate Theses and Dissertations

In 1935, the National Poultry Improvement Plan (NPIP) was created to control Salmonella gallinarum and Salmonella pullorum . These two pathogens were devastating economically for poultry producers. Through cooperative efforts using vaccination and strict biosecurity, these two pathogens were eradicated from the United States. Currently, the NPIP program is targeting two other poultry pathogens, Salmonella enterica serovar Enteritidis and Mycoplasma . In the broiler industry it targets 2 specific Mycoplasma species (synoviae, gallisepticum). Vaccinations for these bacteria are available, but are not fully effective at controlling all strains and serovars. Thus, constant monitoring systems and strict biosecurity measures are necessary …

Host-Virus Interactions Of Infectious Laryngotracheitis Virus Infection In Cultured Cells, Jeong Yoon Lee

Graduate Theses and Dissertations

Infectious laryngotracheitis virus (ILTV; Gallid herpesvirus 1) causes upper respiratory diseases in mainly chickens and exhibits 90-100% of high morbidity and up to 70% of mortality, resulting in huge economic losses in the poultry industry worldwide.

To study host-ILTV interactions, the changes in genome-wide gene expressions in response to wild-type and vaccine ILTV infections in primary chicken embryo lung cells were investigated using microarray analysis. Results provide crucial insights into host cell pathogenic and immunogenic responses against wild-type and vaccine ILTV infections. Using microarray method and Ingenuity Pathway Analysis (IPA) bioinformatics tool, 273 and 306 differentially expressed genes were identified …

Systematics Of Protosteloid Amoebae, Lora Lindley Shadwick

Graduate Theses and Dissertations

Because of their simple fruiting bodies consisting of one to a few spores atop a finely tapering stalk, protosteloid amoebae, previously called protostelids, were thought of as primitive members of the Eumycetozoa sensu Olive 1975. The studies presented here have precipitated a change in the way protosteloid amoebae are perceived in two ways: (1) by expanding their known habitat range and (2) by forcing us to think of them as amoebae that occasionally form fruiting bodies rather than as primitive fungus-like organisms. Prior to this work protosteloid amoebae were thought of as terrestrial organisms. Collection of substrates from aquatic habitats …