Microbiology Commons^™

Synergistic Growth In Bacteria Depends On Substrate Complexity, Yi-Jie Deng, Shiao Y. Wang

Faculty Publications

Both positive and negative interactions among bacteria take place in the environment. We hypothesize that the complexity of the substrate affects the way bacteria interact with greater cooperation in the presence of recalcitrant substrate. We isolated lignocellulolytic bacteria from salt marsh detritus and compared the growth, metabolic activity and enzyme production of pure cultures to those of three-species mixed cultures in lignocellulose and glucose media. Synergistic growth was common in lignocellulose medium containing carboxyl methyl cellulose, xylan and lignin but absent in glucose medium. Bacterial synergism promoted metabolic activity in synergistic mixed cultures but not the maximal growth rate (μ). …

Regulation Of Vancomycin Resistance And Stress Response By The Msaabcr Operon In Staphylococcus Aureus, Dhritiman Samanta

Dissertations

Staphylococcus aureus is the predominant cause of public health problems around the world. Vancomycin has been an important antibiotic against Methicillin Resistant Staphylococcus aureus (MRSA) infections. However, Vancomycin Intermediate S. aureus (VISA) strains have been reported. These strains are characterized by thick cell walls, reduced autolytic rate, reduced PBP4 activity, and increased amount of D-Ala-D-Ala termini in the cell wall. In this study, we show that the msaABCR operon regulates vancomycin resistance in two clinical VISA strains. Deletion of the msaABCR operon in strains Mu50 and HIP6297 resulted in a significant decrease in the minimum inhibitory concentration (MIC) for vancomycin. …

Stressed Induced Changes In Karenia Brevis Ribosomal Rna, David Scott Jayroe

Master's Theses

Karenia brevis is a toxic marine dinoflagellate that causes harmful algal blooms (HABs), also known as red tides, in the Gulf of Mexico. These blooms are responsible for massive fish kills, shellfish bed contaminations, adverse human health effects, and vast economic loss. For these reasons, extensive research has gone into understanding the mechanisms and dynamics of bloom behavior by studying K. brevis in the field and in the lab. In order to understand higher order bloom behavior and dynamics it is imperative to understand K. brevis at the cellular level. In growing K. brevis in vitro under a variety of …

Impacts Of The Deepwater Horizon Oil Spill On Microbial-Mediated Cellulose Decomposition In Mississippi Gulf Coast Salt Marshes, Jerrid Shawn Boyette

Master's Theses

Field studies were conducted to examine the effects of the Deepwater Horizon oil spill on rates of marsh organic matter decomposition. Decomposition in surface and subsurface marsh sediments was assessed in stands of Spartina alterniflora and Juncus roemerianus in 9 Mississippi Gulf Coast marshes exposed to differing oiling intensities. The cotton strip bioassay technique was used as a proxy for cellulose decomposition. In addition, rates of microbial respiration, fungal biomass (ergosterol) and nutrients (C:N, C:P) of surface sediment cotton strips were also quantified. Subsurface cotton strip decay, as determined by losses in tensile strength, were significantly different among marsh …

Characterization And Role Of Msaabcr In Biofilm Development And Virulence In Staphylococcus Aureus, Gyan Sundar Sahukhal

Dissertations

Community-acquired, methicillin-resistant Staphylococcus aureus strains often cause localized infections in immune-compromised hosts, but some strains show enhanced virulence leading to severe infections even among healthy individuals with no predisposing risk factors. The genetic basis for this enhanced virulence has yet to be determined. S. aureus possesses a wide variety of virulence factors, the expression of which is carefully coordinated by a variety of regulators. Several virulence regulators have been well characterized, but others have yet to be thoroughly investigated. Previously, the msa gene as a regulator of several virulence genes, biofilm development, and antibiotic …

Antiviral Responses In Mouse Embryonic Stem Cells: Differential Development Of Cellular Mechanisms In Type I Interferon Production And Response, Ruoxing Wang

Dissertations

Embryonic stem cells (ESCs) have been recognized as a promising cell source for regenerative medicine. Intensive research over the past decade has led to the possibility that ESC-derived cells will be used for the treatment of human diseases. However, increasing evidence indicates that ESC-derived cells generated by the current differentiation methods are not fully functional. It is recently recognized that ESC-derived cells lack innate immunity to a wide range of infectious agents and inflammatory cytokines. When used in patients, ESC-derived cells would be placed in wounded sites that are exposed to various pathogens and inflammatory cytokines; therefore, their viability and …

Large Scale Screening Of Digeneans For Neorickettsia Endosymbionts Using Real-Time Pcr Reveals New Neorickettsia Genotypes, Host Associations And Geographic Records, Stephen Greiman, Vasyl V. Tkach, Eric Pulis, Thomas J. Fayton, Stephen S. Curran

Faculty Publications

Digeneans are endoparasitic flatworms with complex life cycles including one or two intermediate hosts (first of which is always a mollusk) and a vertebrate definitive host. Digeneans may harbor intracellular endosymbiotic bacteria belonging to the genus Neorickettsia (order Rickettsiales, family Anaplasmataceae). Some Neorickettsia are able to invade cells of the digenean's vertebrate host and are known to cause diseases of wildlife and humans. In this study we report the results of screening 771 digenean samples for Neorickettsia collected from various vertebrates in terrestrial, freshwater, brackish, and marine habitats in the United States, China and Australia. Neorickettsia were detected using a …

Study Of The Function Of The Mold Specific Gene Ms95 In Dna Repair In The Pathogenic, Dimorphic Fungus Histoplasma Capsulatum, Erin M. Smith

Honors Theses

Histoplasma capsulatum (Hc) is a dimorphic fungus that is the etiologic agent of the respiratory infection Histoplasmosis that is mediated by a shift from the mold phase to the pathogenic yeast phase. Genes have been identified that are specific to the mold or yeast phase in order to study the molecular biology of this shift. MS95 was identified in a subtractive cDNA library that was enriched for mold-specific genes, and has been found to be homologous to the DNA damage-responsive gene DDR48, which functions in DNA repair in Saccharomyces cerevisiae. In order to elucidate the function of MS95, a …

Molecular Detection Of Tick-Borne Pathogens Associated With Ixodid Tick Species Infesting Migratory Songbirds And Ruminants, Nabanita Mukherjee

Master's Theses

Ticks are hematophagous arthropods and capable of inoculating various infectious agents to their vertebrate hosts. Ticks attached to birds and ruminants are capable of carrying tick-transmitted microorganisms. In our study, the prevalence of tick-borne pathogens was examined in ticks infesting migratory songbirds and Pakistani ruminants. During spring migration seasons, ticks were removed from northward-migrating songbirds in Louisiana and identified as Amblyomma Jongirostre, Amblyomma nodosum, Amb/yomma ca/caratum, Amblyomma maculatum, and Haemaphysalis species, all are considered as Neotropical ticks. Ticks removed from ruminants were identified as Hya/omma anatolicum, Hyalomma dromedarii, Rhipicephalus microplus, and Rhipicephalus sanguineus. A total of 112 and 72 bacterial …

Characterizing The Persistence Of Sewage Enterococci In Mississippi Coastal Waters, Kimberly Anne-Marie Lewis

Master's Theses

Enterococci are microbiological indicators of marine recreation water quality.
Their reliability as fecal indicators is questioned as they are shown to persist in the environment. Multiple laboratory studies on their persistence have been done but few under natural environmental conditions. The purpose of this study was to investigate how long sewage enterococci and enterococcal DNA persist in beach water and to determine whether there is a difference in the genetic diversity and hardiness of sewage vs. environmental isolates. To study persistence, sewage was diluted with beach water, placed in microcosms, and deployed at a beach site in Longbeach and Pass …

Ecology Of Vibrio Parahaemolyticus And Vibrio Vulnificus In The Coastal And Estuarine Waters Of Louisiana, Maryland, Mississippi, And Washington (United States), Crystal N. Johnson, John C. Bowers, Kimberly J. Griffitt, Vanessa Molina, Rachel W. Clostio, Shaofeng Pei, Edward Laws, Rohinee N. Paranjpye, Mark S. Strom, Arlene Chen, Nur A. Hasan, Anwar Huq, Nicholas F. Noriea Iii, D. Jay Grimes, Rita R. Colwell

Faculty Publications

Vibrio parahaemolyticus and Vibrio vulnificus, which are native to estuaries globally, are agents of seafood-borne or wound infections, both potentially fatal. Like all vibrios autochthonous to coastal regions, their abundance varies with changes in environmental parameters. Sea surface temperature (SST), sea surface height (SSH), and chlorophyll have been shown to be predictors of zooplankton and thus factors linked to vibrio populations. The contribution of salinity, conductivity, turbidity, and dissolved organic carbon to the incidence and distribution of Vibrio spp. has also been reported. Here, a multicoastal, 21-month study was conducted to determine relationships between environmental parameters and V. parahaemolyticus …

Alteration Of Microbial Communities Colonizing Leaf Litter In A Temperate Woodland Stream By Growth Of Trees Under Conditions Of Elevated Atmospheric Co2, John J. Kelly, Amit Bansal, Jonathan Winkelman, Lori R. Janus, Shannon Hell, Marie Wencel, Patricia Belt, Kevin A. Kuehn, Steven T. Rier, Nancy C. Tuchman

Faculty Publications

Elevated atmospheric CO₂ can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. Fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. This study tested the hypothesis that changes in leaf chemistry caused by elevated atmospheric CO₂ would result in changes in the size and …

The Pentameric Vertex Proteins Are Necessary For The Icosahedral Carboxysome Shell To Function As A Co2 Leakage Barrier, Fei Cai, Balaraj B. Menon, Gordon C. Cannon, Kenneth J. Curry, Jessup M. Shively, Sabine Heinhorst

Faculty Publications

Background

Carboxysomes are polyhedral protein microcompartments found in many autotrophic bacteria; they encapsulate the CO₂ fixing enzyme, ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) within a thin protein shell and provide an environment that enhances the catalytic capabilities of the enzyme. Two types of shell protein constituents are common to carboxysomes and related microcompartments of heterotrophic bacteria, and the genes for these proteins are found in a large variety of bacteria.

Methodology/Principal Findings

We have created a Halothiobacillus neapolitanus knockout mutant that does not produce the two paralogous CsoS4 proteins thought to occupy the vertices of the icosahedral carboxysomes and related microcompartments. Biochemical …

Transcriptome Analysis Of Frog Virus 3, The Type Species Of The Genus Ranavirus, Family Iridoviridae, Sai Majji, V. Thodima, R. Sample, D. Whitley, Y. Deng, J. Mao, V. Gregory Chinchar

Faculty Publications

Frog virus 3 is the best characterized species within the genus Ranavirus, family Iridoviridae. FV3's large (similar to 105 kbp) dsDNA genome encodes 98 putative open reading frames (ORFs) that are expressed in a coordinated fashion leading to the sequential appearance of immediate early (IE), delayed early (DE) and late (L) viral transcripts. As a step toward elucidating molecular events in FV3 replication, we sought to identify the temporal Class Of Viral messages. To accomplish this objective an oligonucleotide microarray containing 70-mer probes corresponding to each of the 98 FV3 ORFs was designed and used to examine viral gene expression. …

The Role Of Msa In Staphylococcus Aureus Biofilm Formation, Karthik Sambanthamoorthy, Antony Schwartz, Vijayaraj Nagarajan, Mohamed O. Elasri

Faculty Publications

Background

Staphylococcus aureus is an important pathogen that forms biofilms. The global regulator sarA is essential for biofilm formation. Since the modulator of sarA (msa) is required for full expression of sarA and regulates several virulence factors, we examined the capacity of the msa mutant to form biofilm.

Results

We found that mutation of msa results in reduced expression of sarA in biofilm and that the msa mutant formed a weak and unstable biofilm. The msa mutant is able to adhere to surfaces and begins to form biofilm but fails to mature indicating that the defect of the …