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Silicate-Solubilizing Bacteria In Louisiana Soils: Identification, Profiling, And Functions In Crop Production, Jayvee A. Cruz
Silicate-Solubilizing Bacteria In Louisiana Soils: Identification, Profiling, And Functions In Crop Production, Jayvee A. Cruz
LSU Doctoral Dissertations
Studies were conducted to determine the potential of silicate-solubilizing bacteria (SSB) as biostimulant in Louisiana rice (Oryza sativa L.) production systems. Isolation and profiling of SSB in Louisiana soils; evaluation on its effects on the silicon (Si) uptake and productivity of rice using various carriers derived from slag, rice hull, and sugarcane (Officinarum spp.) bagasse; and development of a feasible approach of incorporating SSB to the rice production system were conducted. Results showed that numerous bacteria isolated from Louisiana soils can solubilize silicate and produce multiple plant growth-promoting compounds. These potential SSBs were identified into four genera: Aeromonas, …
Occurrence Of Aflatoxin And Zearalenone In Concentrate Feeds And Milk Contamination With Aflatoxin M1 And Bacterial Pathogens In Malawi, Chunala Alexico Njombwa
Occurrence Of Aflatoxin And Zearalenone In Concentrate Feeds And Milk Contamination With Aflatoxin M1 And Bacterial Pathogens In Malawi, Chunala Alexico Njombwa
LSU Doctoral Dissertations
Multiple studies were conducted in Malawi to: 1) evaluate knowledge and perception of dairy farmers towards molds, mycotoxins and associated adverse effects; 2) evaluate dairy farmers’ knowledge and perception on milk contamination, proper milk handling practices and adverse health effects associated with raw milk consumption; 3) determine levels of aflatoxins and zearalenone (ZEN) in concentrate feedstuffs; 4) assess prevalence and levels of aflatoxin M1(AFM1) in raw milk, dietary exposure and estimate HCC risks to children and adults; 5) assess Salmonella and E. colicontamination in raw and processed milk from selected small scale farms and major …
Development Of A Biosensor System To Detect Bacteria In Food Systems, Luis Alonso Alfaro Sanabria
Development Of A Biosensor System To Detect Bacteria In Food Systems, Luis Alonso Alfaro Sanabria
LSU Doctoral Dissertations
The development of biosensors may assist for the on-site detection of foodborne pathogens. The overall goal of this study was to develop a biosensor system for detecting Listeria innocua (non-pathogenic surrogate bacteria used as a model for pathogenic Listeria monocytogenes) in food systems. The study was divided into three main parts: (1) development of a sample collection and interface system for Listeria innocua from food samples, (2) development of a sample concentration system for the collected bacteria prior detection, and (3) development of a detection system based on a carbon nanotube potentiometric biosensor for a quantitative detection of Listeria innocua. …
Marr Family Transcriptional Regulators From Streptomyces Coelicolor, Hao Huang
Marr Family Transcriptional Regulators From Streptomyces Coelicolor, Hao Huang
LSU Doctoral Dissertations
A family of transcriptional regulators that ubiquitously exists in prokaryotes is the multiple antibiotic resistance regulator (MarR) family. These transcriptional regulators participate in many cellular processes and can provide valuable knowledge about transcriptional regulation in response to specific conditions. The closely related MarR homologs TamR (trans-aconitate methyltransferase regulator) and PecS in Streptomyces coelicolor were studied to investigate their potential role in this bacterium. In Streptomyces coelicolor, the gene (SCO3133), which encodes TamR, is oriented divergently from the tam gene, which encodes trans-aconitate methyltransferase. TamR was found to regulate several target genes, which encode several enzymes closely related to the citric …
Investigations On The Essentiality Of The Escherichia Coli Deda Membrane Protein Family, Lisa A. Boughner
Investigations On The Essentiality Of The Escherichia Coli Deda Membrane Protein Family, Lisa A. Boughner
LSU Doctoral Dissertations
The DedA protein family is a highly conserved family of membrane proteins, with members present throughout all domains of life: Bacteria, Archaea, and Eukarya. Investigation of the DedA membrane protein family began with the isolation of BC202, an Escherichia coli mutant with in-frame deletions of two DedA proteins of unknown function (YqjA and YghB) that share 61% amino acid identity. BC202 demonstrates temperature sensitivity, inefficient cell division, an altered phospholipid composition, increased expression of extracytoplasmic stress response pathways, as well as an inability to maintain the cell membrane proton motive force (PMF). Additionally, Borrelia burgdorferi has a single DedA homolog …
Role Of Nod2/Rip2 Signaling In Acute Bacterial Pneumonia And Sepsis, Balamayooran Theivanthiran
Role Of Nod2/Rip2 Signaling In Acute Bacterial Pneumonia And Sepsis, Balamayooran Theivanthiran
LSU Doctoral Dissertations
Bacterial pneumonia and sepsis are two important causes of mortality in the world. Emergence of multidrug resistant bacteria has necessitated the development of new treatment and/or prevention strategies to augment host immune defense. In this context, the innate host defense is critical in clearing pathogenic bacteria from the host. Early neutrophil recruitment is a critical step in a multistep requence leading to bacterial clearance. Pattern recognition receptors (PRRs) play a critical role in the innate immune system. Receptor interacting protein 2 (RIP-2) is an adaptor for the nod-like receptors (NLR) NOD1 and NOD2. Nucleotide oligomerisation domain 2 (NOD2) is an …
Diversity And Activity Of Aerobic Thermophilic Carbon Monoxide-Oxidizing Bacteria On Kilauea Volcano, Hawaii, Caitlin Elizabeth King
Diversity And Activity Of Aerobic Thermophilic Carbon Monoxide-Oxidizing Bacteria On Kilauea Volcano, Hawaii, Caitlin Elizabeth King
LSU Doctoral Dissertations
Aerobic carbon monoxide (CO) oxidation is used by phylogenetically and physiologically diverse microorganisms inhabiting a variety of terrestrial and aquatic ecosystems. Activity assays, culture-based studies, and molecular-based approaches targeting the coxL gene, encoding the large subunit of CO dehydrogenase, were used to investigate the role of temperature in structuring CO-oxidizing communities at Kilauea Volcano, Hawai’i. CO uptake activity was assessed for unvegetated and vegetated temperate volcanic deposits that experience different temperature regimes due to plant development during ecosystem succession. Both CO-oxidizing communities had similar short-term responses to temperature; however, results from extended incubations (30 d) at elevated temperature (55 °C) …
Essential Role Of Monocyte Chemoattractant Protein-1 In Gram-Negative Bacterial Pneumonia, Gayathriy Balamayooran
Essential Role Of Monocyte Chemoattractant Protein-1 In Gram-Negative Bacterial Pneumonia, Gayathriy Balamayooran
LSU Doctoral Dissertations
Acute gram-negative bacterial infections are a leading cause of mortality among the nosocomial infections. Increasing numbers of immunosuppressed individuals and growing numbers of antibiotic resistant strains make antibiotic treatment difficult. Neutrophils are the first cells recruited to the site of infection and are critical players in the host defense against gram-negative bacterial pneumonia. Therefore, identification of targets that boost neutrophil-associated host defense in the lung is essential in designing better therapies to control pulmonary infections. Production of chemokines is an important step for neutrophil recruitment. Monocyte chemoattractant protein-1 (MCP-1) is a chemokine that is important for monocyte and T-lymphocyte influx. …
Investigating The Physiological Roles Of Yqja And Yghb: Members Of The Conserved Deda Membrane Protein Family In Escherichia Coli, Rakesh Sikdar
Investigating The Physiological Roles Of Yqja And Yghb: Members Of The Conserved Deda Membrane Protein Family In Escherichia Coli, Rakesh Sikdar
LSU Doctoral Dissertations
The aim of this dissertation is to characterize the physiological roles of E. coli YqjA and YghB, which belong to the ancient and conserved DedA protein family of hitherto unknown functions. YqjA and YghB are inner membrane (IM) proteins with 61% amino acid identity and share partially redundant functions. Such characterization is achieved by addressing the phenotypes exhibited by strain BC202 with in-frame deletions of yqjA and yghB. BC202 exhibits cell division defects, inability to grow at temperatures above 42°C and an altered phospholipid composition. The cell division defect of BC202 is attributed to the inefficient secretion of periplasmic amidases …
Highly Efficient Selection, Enumeration, Enrichment, And Molecular Profiling Of Low-Abundance Biological Cells, Udara R. Dharmasiri Rasika Dharmasiri
Highly Efficient Selection, Enumeration, Enrichment, And Molecular Profiling Of Low-Abundance Biological Cells, Udara R. Dharmasiri Rasika Dharmasiri
LSU Doctoral Dissertations
After brief overviews of low-abundance cell selection techniques in chapter 1 and circulating tumor cells in chapter 2, this dissertation initially focuses on the development of aptamer incorporated high-throughput microfluidic techniques to select rare circulation prostate cancer cells (LNCaP) directly from whole blood with subsequent quantification of these rare cells using a non-labeling approach. Then, I extended the technology to environmental samples in an effort around time, sensitivity, and portability of traditional groundwater assessment. As a model bio- pathogen, E. coli O157:H7 was chosen due to its toxicity and its adverse impact on recreational waters. Low-abundance (<100 cells mL-1) E. coli O157:H7 cells were isolated and enriched from environmental water samples using a microfluidic chip that its capture beds were covalently decorated with E.coli O157:H7 specific polyclonal antibodies. The selected cells were enumerated using RT-qPCR technique. Finally, I have integrated HTMSU with electrokinetic enrichment microfluidic unit for performance of single recombinant low-abundance CTC cell-based assay. A series of analytical processes were carried out, including immunoaffinity selection of rare CTCs, quantification of selected cells via conductivity impedance and electrophoretic enrichment of selected cells for PCR/LDR/CE interrogation for detection of low-abundance point mutations in genomic DNA.
Microfluidic Devices Interfaced To Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For Proteomics, Jeonghoon Lee
Microfluidic Devices Interfaced To Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For Proteomics, Jeonghoon Lee
LSU Doctoral Dissertations
Microfluidic interfaces were developed for off-line matrix-assisted laser desorption/ionization mass spectrometry (MALDI). Microfluidic interfaces allow samples to be manipulated on-chip and deposited onto a MALDI target plate for analysis. For this research, microfluidic culturing devices and automated digestion and deposition microfluidic chip platforms were developed for the identification of proteins. The microfluidic chip components were fabricated on a poly(methyl methacrylate), PMMA, wafer using the hot embossing method and a molding tool with structures prepared via micromilling. One of the most important components of the chip system was a trypsin microreactor. An open channel microreactor was constructed in a 100 µm …
Temperature Impact On Nitrification And Bacterial Growth Kinetics In Acclimating Recirculating Aquaculture Systems Biofilters, Milton Maada-Gomoh Saidu
Temperature Impact On Nitrification And Bacterial Growth Kinetics In Acclimating Recirculating Aquaculture Systems Biofilters, Milton Maada-Gomoh Saidu
LSU Doctoral Dissertations
This project assessed short-term temperature effects on total ammonia nitrogen (TAN) utilization rates in a batch laboratory-scale recirculating system. The tank system was designed for experiments on short term steady state and diurnal temperatures. A set of numerical models was developed to simulate observed results. The performance of the biofilters was determined with three tank replicates at fixed temperatures of 13, 20 and 300C; and at diurnal transient (sinusoidal) temperature regimes of (20 ± 30C; 30 ± 30C). Ammonia utilization rates and biofilter performance for beads acclimated at different temperatures regimes separated and mixed were also determined. Total ammonia utilization …
Bacterial Characterization Of Louisiana Groundwater Contaminated By Dnapl-Containing Chloroethanes And Other Solvents, Kimberly Bowman
Bacterial Characterization Of Louisiana Groundwater Contaminated By Dnapl-Containing Chloroethanes And Other Solvents, Kimberly Bowman
LSU Doctoral Dissertations
In support of an effort to determine the feasibility of using an in-situ bioremediation strategy for cleanup of groundwater in an area containing chlorinated solvents present as a dense non-aqueous phase liquid (DNAPL), the bacterial population in the groundwater at a Superfund site located near Baton Rouge, Louisiana was characterized. More than 3¡Á107 cells/mL in the groundwater were observed via microscopy. Universal bacterial and ¡°Dehalococcoides¡±-specific 16S rRNA gene libraries were constructed and analyzed. Universal clones grouped into 18 operational taxonomic units (OTUs), as defined by sequence similarity ¡Ý97.0%, which included several as yet undescribed organisms. Multiple unique sequences closely related …
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry For The Analysis Of Collected Bioaerosols, Alton John Dugas
LSU Doctoral Dissertations
The goal of this dissertation was to demonstrate collection, detection and identification of microorganisms from bioaerosols using offline matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for the analysis of proteins. MALDI-MS intact bacteria techniques were adapted for use with an orthogonal MALDI quadrupole-time-of-flight mass spectrometer. Results indicate the instrument is capable of analyzing intact whole-cells. The first phase was to evaluate three bioaerosol samplers, an Andersen N6 single-stage impactor (AI), a cyclone impactor, and a vacuum filter system. The samplers collected test bioaerosols using a constructed bioaerosol exposure chamber (BEC). The BEC allowed all three samplers to operate in parallel. Each …
Biotransformation Of Organic Wood Preservatives By Micro-Organisms, Diana Nasirumbi Obanda
Biotransformation Of Organic Wood Preservatives By Micro-Organisms, Diana Nasirumbi Obanda
LSU Doctoral Dissertations
Wood products are treated with biocides to prevent biodegradation by bacteria, fungi, and insects. Much attention is being directed towards testing of metal-free organic preservative systems. The major disadvantage of organics is that they are biotransformed by micro-organisms in soil and wood. This study explored the biotransformation of the fungicide tebuconazole by a bacteria species (Pseudomonas fluorescens), the mold (Trichoderma harzianum), the white rot fungus (Phanerochaete chrysosporium) and the brown rot (Meruliporia incrassata). After incubation of cultures spiked with tebuconazole, samples were analyzed for chemical remaining and metabolites. M. incrassata, T. harzianum, and the bacterium all cleaved the 1, 2, …