Microbiology Commons^™

Non-Thermal Plasma Inactivation Of Bacillus Amyloliquefaciens Spores, Yaohua Huang

Masters Theses

Bacterial spores have remarkable resistance to a variety of harsh conditions, causing spoilage in food industry and becoming the primary bacterial agent in biowarfare and bioterrorism. In this study, inactivation mechanisms of Bacillus amyloliquefaciens (BA) spores by non-thermal plasma (NTP) were investigated by using Fourier-transform infrared spectroscopy (FTIR) as a major tool to exam spores after NTP treatment. Chemometric techniques, such as multivariate classification models based on soft independent modeling of Class Analogy (SIMCA) and Principal Component Analysis (PCA), were employed to identify functional group changes in FTIR spectra. The IR absorbance bands correlated to dipicolinic acid (DPA) decreased after …

Evaluation Of Chromosomally-Integrated Luxcdabe And Plasmid-Borne Gfp Markers For The Study Of Localization And Shedding Of Stec O91:H21 In Calves, Yingying Hong

Masters Theses

Shiga toxin-producing Escherichia coli (STEC) has been recognized as an important foodborne pathogen. Of this group, O91 is one of the common serogroups frequently isolated from patients and food in some countries, with O91:H21 being previously implicated in hemolytic uremic syndrome (HUS). Cattle are principle reservoirs for STEC, and studies examining STEC shedding in cattle often include experimental inoculation of strains of interest using antibiotic resistance markers for identifiable recovery. However, indigenous fecal microbes exhibiting similar resistance patterns can confound such studies. Such was the case in a study by our group when attempting to characterize shedding patterns of O91:H21 …

Functional Cloning And Characterization Of Antibiotic Resistance Genes From The Chicken Gut Microflora, Wei Zhou

Masters Theses

A recent study using human fecal samples in conjunction with a culture-independent approach revealed immense diversity of antibiotic resistance (AR) genes in the human gut microflora. We hypothesize that food animal gut microflora also contain diverse and novel AR genes which could contribute to the emergence and transmission of AR in pathogens important in animal and human health. To test this, we examined AR reservoir in chicken gut microflora using a metagenomic, functional cloning method. Total genomic DNA was extracted from individual cecal contents of two free range chickens and two conventionally raised chickens. The DNAs were physically sheered into …

Study Of Population Diversity Of Toxoplasma Gondii, Debashree Majumdar

Masters Theses

Toxoplasma gondii, the causal agent of toxoplasmosis, is an important water and food borne protozoan parasite. T. gondii was previously shown to have a distinct clonal population structure composed of Type I, II and III lineages in North America and Europe. But more recent studies demonstrated high diversity in South America. In the present project we have conducted an intensive study of the population diversity of T. gondii and surveyed the extent of genetic variation among natural T. gondii isolates on a global scale in order to better understand the population dynamics and pathogenesis of this parasite. To this …

Characterizing Cell-Cell And Cell-Surface Interactions In The Rhizobacterium Azospirillum Brasilense, Calvin Shay Green

Masters Theses

Microaerophilic and chemotaxic diazotrophs, azospirilla are found in close association with certain cereals such as durum wheat and maize and are active in enriching these ecological niches with the macronutrient nitrogen as ammonia. Regarded as highly pleomorphic, Azospirillum spp. are highly motile, using either a single polar flagellum when grown in liquid environments or peritrichous lateral flagella in viscous environments. Additionally, azospirilla are able to adhere onto surfaces as a biological film or aggregate cell-to-cell as nonproliferating flocculi, and these two processes having been suggested as positively affecting the survival and dispersal of the bacteria in the soil. Even though …

Influenza-Specific B Cell Responses In Hla-Dr1 Transgenic Mice, Lifang Huan

Masters Theses

HLA-DR1 transgenic (DR1 Tg) mice provide a model for evaluating the breadth and specificity of CD4 T cell responses that may develop in humans following influenza infection or vaccination. Recent studies identified a tremendously broad HLA-DR1-restricted CD4 T cell responses in DR1 Tg mice infected intranasally with influenza A/New Caledonia/20/99 (NC). In this study, our goals were to characterize B cell responses after NC infection in DR1 Tg mice and establish the correlation between B cell responses and CD4 T cell responses in this system. Influenza-specific B cell responses following virus administration were analyzed in DR1 Tg mice and in …

Cattle Access Affects Periphyton Community Structure In Tennessee Farm Ponds., Robert Gerald Middleton

Masters Theses

Cattle farming is vital to the economy of the United States. Frequently, cattle are given access to ponds and streams for water. The relative impacts of cattle access in natural water sources on the periphyton community have been rarely investigated. Periphyton is the basis of the aquatic food web, and community composition can serve as a bioindicator of pollution. Thus, my objectives were to quantify the effects of cattle access in aquatic lentic systems on periphyton community structure and biovolume, identify taxa that were associated with cattle access, and identify abiotic mechanisms that might be driving assemblage changes. I conducted …

Agricultural Soil Bacteria; A Study Of Collection, Cultivation, And Lysogeny, Katherine Elizabeth Sides

Masters Theses

The aim of this research project was to test new collection and cultivation techniques that may increase the range of cultivable diversity of soil bacteria. Fortified BioSep beads were employed in situ to capture soil bacteria, and the success of the beads was analyzed using Phylochip microarray analysis. In the cultivation phase, three different media substrates and increased incubation period were evaluated for the ability to select novel or rare bacteria. Over 700 agricultural soil bacterial isolates were classified, including a rare Gemmatimonadetes sp., a rare Verrucomicrobia sp., several Acidobacteria sp., and many novel isolates. Land management, media, and incubation …

In Vitro Analysis Of The Anti-Influenza Virus Activity Of Pomegranate Products And Fulvic Acid, Radha Ganapathy

Masters Theses

In traditional cuban medicine, pomegranate fruits have been used to treat acidosis, dysentery, microbial infections, diarrhoea, helminthiasis; haemorrhage and respiratory pathologies [Vuorela et al., 2003; Roig, 1974; Jimenez et al., 1979; Seoane, 1984].Pomegranates contain high levels of Polyphenolic compounds, which are largely responsible for the fruit’s antioxidant properties. A number of studies have demonstrated that polyphenolic complexes derived from other plants have antiviral effects, suggesting that antiviral activity may also reside in the polyphenol (PP) fraction of pomegranates.

The decay of organic matter generates an extremely heterogeneous mixture of organic molecules referred to as humic substances. They are sub-classified on …

Introduction Of Mycobacterium Ulcerans Mycolactone Genes Into A Heterologous Host, Samantha Elizabeth Wirth

Masters Theses

Mycobacterium ulcerans is the causative agent of Buruli ulcer (BU), a necrotizing skin disease endemic to West Africa and Australia. The cytopathicity, cell cycle arrest and immunosuppression characteristic of BU are attributed to the production of a plasmid-encoded, macrolide toxin, mycolactone. The core of mycolactone is a product of two large polyketide synthases (PKS) and is conserved among all mycolactone congeners. Heterogeneity of the toxin is a result of differences in the polyketide side chain, the product of a third PKS. The mycolactone plasmid (MP) was initially thought to be restricted to M. ulcerans. However, other mycolactone producing mycobacteria …

Development Of A Bacteriophage Based Bioluminescent Bioreporter System For The Detection Of Escherichia Coli K12 And O157:H7, Courtney M. Johnson

Masters Theses

Detection of pathogenic bacteria in the environment and food products is of increasing importance especially in light of recent outbreaks of Escherichia coli O157:H7. I describe here a bacteriophage based bioluminescent bioreporter method for E. coli O157:H7 detection that combines the specificity bacteriophage have for their host, quorum sensing, and lux based bioluminescence from Vibrio fischeri. This new method for detection of E. coli utilizes the luxI/luxR quorum sensing present in V. fischeri which uses N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) as an autoinducer (Miller & Bassler 2001). Once the concentration of OHHL is high enough it binds the LuxR protein …

Characterization Of Motility And Surface Attachment In Thirteen Members Of The Roseobacter Clade, Rachael N. Slightom

Masters Theses

The Roseobacter clade is an abundant and biogeochemically relevant group of marine bacteria. Physiological and ecological traits identified in specific representatives of the clade are often universally attributed to all Roseobacter group members, however, culture-dependent studies utilizing phylogenetically distinct members are rare. Other attributes often associated with this clade include motility, biofilm formation and surface attachment, chemotaxis and quorum sensing. This study compared a collection of 13 diverse Roseobacter strains both pheno- and genotypically on the basis of these traits. Motility was determined for seven previously uncharacterized strains, with five of the strains demonstrating motility. Microscopic analysis using both phase …

The Role Of Soluble Fibrin In Lymphocyte And Lak Cell Adherence To And Migration Across Vascular Endothelial Cells: Implications For Immunotherapy And Cancer, Brandy Lee Weidow

Masters Theses

Although conventional therapies for metastatic cancers have made significant progress in recent years, they are relatively nonspecific and have many deleterious side-effects. Recently, novel therapies, including adoptive cellular immune therapies have had sporadic, but spectacular success in cancers such as malignant melanoma and renal cell carcinoma: tumors in which an immune response has been demonstrated. However, other physiological mechanisms, such as blood coagulation inhibit the immune response against cancers. Our previous work has shown that one of these coagulation proteins, soluble fibrin (sFn), inhibits unstimulated and activated lymphocyte adherence to tumor cells by blocking leukocyte integrin (CD11a/CD18) binding to tumor …

The Bovine Coronavirus 2'-O-Methyltransferase Binds Cis-Acting Stem-Loop Iv In The 5-Prime Untranslated Region Of The Viral Genome, Tara Beth Tucker

Masters Theses

The positive-stranded coronavirus genome, at 32 kilobases in length, is the largest known viral RNA genome, and internal cis-signaling elements directing its replication have been described only within the last ten years. The bovine coronavirus genome encodes 26 proteins in the region between the 5’-terminal 210-nt untranslated region and the 3’-terminal 298-nt untranslated region. Here, genes for 5 of the 26 proteins were cloned into bacterial expression plasmids for the long-term goals of characterizing enzymatic and RNA binding properties. These genes encode enzymes postulated to interact directly with the cis-acting RNA elements and carry out RNA synthesis, namely, the …

Cloning And Expression Of A Putative P450 From Mycobacterium Ulcerans, Yang Wang

Masters Theses

Mycolactones are macrocyclic polyketide toxins produced by the pathogen Mycobacterium ulcerans, the etiologic agent of the emerging human disease known as Buruli ulcer. A giant virulence plasmid in Mycobacterium ulcerans encoding giant polyketide synthases is responsible for the synthesis of the lipid toxin mycolactone. Mycobacterium ulcerans from different geographic origins produce varieties of mycolactones including mycolactone A/B, C E. Their difference is observed by thin layer chromagraph, mass spectrometry, cytopathic assays. The presence of different mycolactone correlates with plasmid variation. Australian strains lacking the hydroxyl group at C-12’ produce a mycolactone with a mass of [M + Na]+ at …

Virus Dynamics In High-Nutrient, Low-Chlorophyll Marine Surface Waters, Julie Linda Higgins

Masters Theses

Iron (Fe) limitation of primary productivity in high-nutrient, low-chlorophyll (HNLC) regions is relatively well-studied. Iron fertilization experiments as well as bottle incubations have been used to study changes in phytoplankton community biomass and diversity, changes in bacterial growth rates, etc. However, viral activity has been largely ignored in these studies. Viral activity was monitored during an iron budget study (FeCycle) in the HNLC waters of the Southern Ocean southwest of New Zealand as well as during a mesoscacle iron fertilization in the subarctic Pacific (SEEDS II). The goal of these studies was to evaluate the role of viruses in the …

Sol-Gel Encapsulation Of A Bioluminescent Bioreporter, Elizabeth F. Mitchell

Masters Theses

Genetic engineering has allowed for the development of a number of whole-cell bacterial bioreporters. In order for these cells to be used in certain devices and field applications, they must be maintained, and protected, but exposed to environmental conditions. One approach used to accomplish this goal is cellular encapsulation. The recent development of techniques to form inorganic matrices, in particular through the sol-gel process, displays promise as a system of encapsulation. The silica sol-gel process was originally designed for the fabrication of glass, and given that reactions are performed in standard lab conditions and room temperature, the process can be …

Identifying The Signature Of The Natural Attenuation Of Mtbe In Groundwater Using Molecular Methods And "Bug Traps", Anita Eva Biernacki

Masters Theses

Natural attenuation through intrinsic bioremediation is the risk-based management approach commonly used for gasoline (BTEX) contamination sites. This approach has not yet been utilized for the fuel oxygenate methyl tertiary-butyl ether (MTBE). MTBE is more resistant to biodegradation than BTEX. MTBE is more abundant than benzene in oxygenated gasoline, has a greater water solubility than BTEX, and sorbs weakly to soil. These properties complicate developing a risk based management option to be implemented as easily as for BTEX. The purpose of this project is to contribute to a growing database containing information on MTBE contaminated sites nationwide with a variety …

The Effects Of Iron On Growth And Physiology Of The Cyanobacterium Microcystis Aeruginosa, Shannon Pedigo Efteland

Masters Theses

To determine the effects of iron on the growth of the cyanobacterium Microcystis aeruginosa, a series of growth and iron uptake experiments were conducted. Studies included the effects of iron and organic iron-binding chelators on batch cultures of known bacteria and on the natural community of Lake Erie, where blooms of M. aeruginosa have been documented since 1995. Results of growth rate studies under iron limitation suggest that M. aeruginosa uses an active, high-affinity transport system to acquire iron after a lag time at initial limitation. Further studies indicate that cells continue to take up nutrients and possibly metals, while …

Expression Of Luxi In Bacillus Thuringiensis For The Development Of A Bacteriophage-Based Bioreporter System For The Detection Of Anthrax, Amy Tomaszewski

Masters Theses

In light of the recent anthrax attacks of 2001in the United States, the need for a rapid, sensitive, and real-time surveillance system for detecting pathogenic bacteria has become readily apparent. A proof-of-principle study involving development of a bacteriophage-based bioreporter system for the detection of Bacillus anthracis spores has been initiated in the surrogate strain Bacillus thuringiensis 4Q7. The final goal of the project is to develop an engineered bacteriophage with the luxI gene from Vibrio fischeri, which upon infection of the target organism, would produce the signal molecule, N-(3-oxohexanoyl)-L-homoserine lactone (OHHL), capable of inducing bioluminescence in a neighboring …

Molecular Approaches In Attempts To Identify The Flagellin B-Type Gene In Clone Pkw52, Yolanda F. Kirkpatrick

Masters Theses

Pseudomonas aeruginosa is an important pathogen for susceptible individuals particularly those immunocompromised due to the prolonged use of drugs, noscomial infections, burns, or cancer. In addition, P. aeruginosa infections are high among cystic fibrosis patients. P. aeruginosa presents a unique health concern and challenge for researchers due to its multiple virulence factors and the increasing number of patients developing P. aeruginosa infections. P. aeruginosa produces a variety of toxins and enzymes. The flagellum of P. aeruginosa allows the bacterium to be motile. Motility has enabled the P. aeruginosa bacterium to rapidly colonize the host's body.

The major structural component of …

Adaptation To Growth At Low Ph By Clostridium Sporogenes, Claudia Dee Crosthwait

Masters Theses

The ability of Clostridium sprogenes to adapt to growth at low pH was studied in tomato serum prepared by enzymatic hydrolysis of canned tomatoes and tomato juice. The lowest pH at whicn C. sporogenes could grow before adaptation in tomato serum, Trypticase Peptone Glucose Yeast Extract (TPGY) and fluid thioglycollate broths was pH 5.4.

Tomato serum and TPGY or fluid thioglycollate broth adjusted to varying pH levels were inoculated with C. sporogenes from tubes with growth at the lower pH values. Subsequent transfers of C. sporogenes grown in tomato serum were made to tomato serum of equal and lower pH …