Microbial Physiology Commons^™

Dissecting The Mechanism Of Action Of A Novel Antifungal Peptide, Cody Bullock

Graduate Theses and Dissertations

There is an urgent need for novel treatments for Candida infections. The utility of antimicrobial peptides for antifungal therapy has garnered interest in recent years. One promising family of peptides is the Histatins, a family of naturally-occurring peptides secreted into the oral cavity that display antimicrobial activity. Histatin 5 is a twenty-four amino acid peptide with strong antifungal activity. Studies from our laboratory have identified a small histatin-derived peptide, KM29, that yields fungicidal activity 10-fold greater than Histatin 5 against multiple Candida species. Our laboratory has focused on understanding the mechanism of action of KM29 to further develop it as …

A Broad Spectrum Racemase In Pseudomonas Putida Kt2440 Plays A Key Role In Amino Acid Catabolism, Atanas D. Radkov, Luke A. Moe

Plant and Soil Sciences Faculty Publications

The broad-spectrum amino acid racemase (Alr) of Pseudomonas putida KT2440 preferentially interconverts the L- and D-stereoisomers of Lys and Arg. Despite conservation of broad-spectrum racemases among bacteria, little is known regarding their physiological role. Here we explore potential functional roles for Alr in P. putida KT2440. We demonstrate through cellular fractionation that Alr enzymatic activity is found in the periplasm, consistent with its putative periplasm targeting sequence. Specific activity of Alr is highest during exponential growth, and this activity corresponds with an increased accumulation of D-Lys in the growth medium. An alr gene knockout strain (Δalr) was generated …

Identification Of A Tola Protein Binding Site For Bacterial Toxins, Monica Ferrante

Honors Projects

Group A colicins are proteinaceous bacteriocins encoded by plasmids that exploit the cellular envelope protein TolA to translocate the cell wall barrier and cellular envelope of the bacterium Escherichia coli. These colicins offer protocols for studying certain protein-protein interactions involved in such membrane transport functions. Previous experimentations suggest the carboxyl-terminal domain of TolA protein contains specific amino acid binding regions required for the translocation of group A colicins into E. coli. The amino acid sequence of this domain varies between E. coli and other gram-negative bacterial species. It has been suggested that this diversity could be utilized to …

Regulation Of The Tubulin Homolog Ftsz In Escherichia Coli, Monika S. Buczek

Dissertations, Theses, and Capstone Projects

Escherichia coli is a well-known pathogen, and importantly, a widely used model organism in all fields of biological sciences for cloning, protein purification, and as a model for Gram-negative bacterial species. And yet, researchers do not fully understand how this bacterium replicates and divides. Every year additional division proteins are discovered, which adds complexity to how we understand E. coli undergoes cell division. Due to their specific roles in cytokinesis, some of these proteins may be potential targets for development of antibacterials or bacteriostatics, which are much needed for fighting the current global antibacterial deficit. My thesis work focuses on …

The Effect Of Cellular Dehydration On Glucose Regulation In Lean And Obese Females, Chunbo Yang

Graduate Theses and Dissertations

A chronically elevated vasopressin level has been associated with an impaired glucose regulation system in humans. A recent study in patients with diabetes suggested that low water intake is associated with impaired glucose regulation. The aim of this study was to examine the effect of hypertonic saline infusion on glucose regulation in healthy females. Thirty healthy, non-diabetic females performed a 2-h infusion followed by a 4-h oral glucose tolerance test (OGTT). Every subject participated in two trials separated by one month, in a counterbalanced order. Two trials were identical in the procedure, differing in the concentration of saline infusion, with …

Bioprospecting Deep-Sea Actinobacteria For Novel Anti-Infective Natural Products, Dongbo Xu, Linna Han, Chunhui Li, Qi Cao, Duolong Zhu, Nolan H. Barrett, Dedra Harmody, Jing Chen, Haining Zhu, Peter J. Mccarthy, Xingmin Sun, Guojun Wang

Molecular and Cellular Biochemistry Faculty Publications

The global prevalence of drug resistance has created an urgent need for the discovery of novel anti-infective drugs. The major source of antibiotics in current clinical practice is terrestrial actinobacteria; the less-exploited deep-sea actinobacteria may serve as an unprecedented source of novel natural products. In this study, we evaluated 50 actinobacteria strains derived from diverse deep water sponges and environmental niches for their anti-microbial activities against a panel of pathogens including Candida albicans, Clostridium difficile, Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA), and Pseudomonas aeruginosa. More than half of the tested strains (27) were identified as …

Predator-By-Environment Interactions Mediate Bacterial Competition In The Dictyostelium Discoideum Microbiome, R Fredrik Inglis, Odion Asikhia, Erica Ryu, David C. Queller, Joan E. Strassmann

Biology Faculty Research

Interactions between species and their environment play a key role in the evolution of diverse communities, and numerous studies have emphasized that interactions among microbes and among trophic levels play an important role in maintaining microbial diversity and ecosystem functioning. In this study, we investigate how two of these types of interactions, public goods cooperation through the production of iron scavenging siderophores and predation by the social amoeba Dictyostelium discoideum, mediate competition between two strains of Pseudomonas fluorescens that were co-isolated from D. discoideum. We find that although we are able to generally predict the competitive outcomes between …

An Insoluble Iron Complex Coated Cathode Enhances Direct Electron Uptake By Rhodopseudomonas Palustris Tie-1, Karthikeyan Rengasamy, Tahina Ranaivoarisoa, Rajesh Singh, Arpita Bose

Biology Faculty Research

Microbial electrosynthesis (MES) is a promising bioelectrochemical approach to produce biochemicals. A previous study showed that Rhodopseudomonas palustris TIE-1 can directly use poised electrodes as electron donors for photoautotrophic growth at cathodic potentials that avoid electrolytic H₂ production (photoelectroautotrophy). To make TIE-1 an effective biocatalyst for MES, we need to improve its electron uptake ability and growth under photoelectroautotrophic conditions. Because TIE-1 interacts with various forms of iron while using it as a source of electrons for photoautotrophy (photoferroautotrophy), we tested the ability of iron-based redox mediators to enhance direct electron uptake. Our data show that soluble iron cannot …

Insights Into Key Gene Regulatory Networks In Borrelia Burgdorferi, William Kenneth Arnold

Theses and Dissertations--Microbiology, Immunology, and Molecular Genetics

Gene regulatory networks are composed of interconnected regulatory nodes created by regulatory factors of multiple types. All organisms finely tune gene expression in order to adapt to and survive within their current niche. Obligate parasitic bacteria are under extreme pressure to quickly and appropriately adapt their gene regulatory programs in order to survive within their given host. Borrelia burgdorferi is one such organism and persists in nature by alternating between two hosts; Ixodes spp. ticks and small vertebrate animals. These two hosts represent drastically different environments; requiring a unique gene regulatory program to survive and transmit between them. Microbiologists have …

The Bi-Directional Relationship Between Gut Microbiota And Autoimmunity, Trevor O. Kirby

EWU Masters Thesis Collection

Humans serve as a major reservoir for a vast number of microbiota. These microbes have evolved symbiotic relationships with humans due to their close proximity with their host. As a result, the immune system adapts to the microbiota thus modulating immunological function. Autoimmunity is a state in which there are aberrant immune responses produced against host tissue. Intestinal bacteria are directly impacted by instances of inflammation brought on by autoimmunity. The complicated nature between autoimmunity and bacterial modulation demonstrates a bi-directional relationship. Here, we utilize experimental autoimmune encephalomyelitis, a model for multiple sclerosis, to explore the bi-directional relationship that disease …

Relationships Between Factors Influencing Biofilm Formation And Pathogen Retention In Complex Rhizosphere Microbial Communities, Aaron Coristine

Theses and Dissertations (Comprehensive)

Riparian wetlands are unique habitats facilitating all forms of life. The riverbanks of these environments provide ideal conditions for bacteria, plants, and higher organisms. Of particular interest to this research was the variation in microbial community structure at high, intermediate and poor water quality impacted areas. Assessing the capabilities of plants to retain microbial pathogens was identified. Root systems and corresponding soil are ideal locations for bacterial deposition, resulting in attachment at these areas. Biofilm production in these regions is important for long-term establishment, leading to persistence and potential naturalization. Opportunistic pathogens originating from mammalian fecal matter are introduced into …

Anaerobic Oxidation Of Ethane, Propane, And Butane By Marine Microbes: A Mini Review, Rajesh Singh, Michael S. Guzman, Arpita Bose

Biology Faculty Research

The deep ocean and its sediments are a continuous source of non-methane short-chain alkanes (SCAs) including ethane, propane, and butane. Their high global warming potential, and contribution to local carbon and sulfur budgets has drawn significant scientific attention. Importantly, microbes can use gaseous alkanes and oxidize them to CO₂, thus acting as effective biofilters. A relative decrease of these gases with a concomitant ¹³C enrichment of propane and n-butane in interstitial waters vs. the source suggests microbial anaerobic oxidation. The reported uncoupling of sulfate-reduction (SR) from anaerobic methane oxidation supports their microbial consumption. To date, strain …

Tumor Necrosis Factor Dynamically Regulates The Mrna Stabilome In Rheumatoid Arthritis Fibroblast-Like Synoviocytes, Konstantinos Loupasakis, David Kuo, Upneet K. Sokhi, Christopher Sohn, Bethany Syracuse, Eugenia G. Giannopoulou, Sung Ho Park, Hyelim Kang, Gunnar Rätsch, Lionel B. Ivashkiv, George D. Kalliolias

Publications and Research

During rheumatoid arthritis (RA), Tumor Necrosis Factor (TNF) activates fibroblast-like synoviocytes (FLS) inducing in a temporal order a constellation of genes, which perpetuate synovial inflammation. Although the molecular mechanisms regulating TNF-induced transcription are well characterized, little is known about the impact of mRNA stability on gene expression and the impact of TNF on decay rates of mRNA transcripts in FLS. To address these issues we performed RNA sequencing and genome-wide analysis of the mRNA stabilome in RA FLS. We found that TNF induces a biphasic gene expression program: initially, the inducible transcriptome consists primarily of unstable transcripts but progressively switches …

Development Of A Core Clostridium Thermocellum Kinetic Metabolic Model Consistent With Multiple Genetic Perturbations, Satyakam Dash, Ali Khodayari, Jilai Zhou, Evert K. Holwerda, Daniel Olson, Lee Lynd, Costas Maranas

Dartmouth Scholarship

Clostridium thermocellum is a Gram-positive anaerobe with the ability to hydrolyze and metabolize cellulose into biofuels such as ethanol, making it an attractive candidate for consolidated bioprocessing (CBP). At present, metabolic engineering in C. thermocellum is hindered due to the incomplete description of its metabolic repertoire and regulation within a predictive metabolic model. Genome-scale metabolic (GSM) models augmented with kinetic models of metabolism have been shown to be effective at recapitulating perturbed metabolic phenotypes.

In this effort, we first update a second-generation genome-scale metabolic model (iCth446) for C. thermocellum by correcting cofactor dependencies, restoring elemental and charge balances, …

Determination Of The Effects That A Previously Uncharacterized Secreted Product From Klebsiella Pneumoniae Has On Citrobacter Freundii And Enterobacter Cloacae Biofilms, Cody M. Hastings

Undergraduate Honors Theses

More so than ever, Multiple Drug Resistant (MDR) bacteria are on the rise due to overuse of antibiotics along with natural selection for adaptations that enhance drug-resistant properties. One particular bacterial family, Enterobacteriaceae, has been problematic, exhibiting several bacterial members that have developed a precipitous resistance to modern antibiotics and are also primary causative agents of nosocomial, or hospital acquired, infections. Citrobacter freundii (CF) and Enterobacter cloacae (ECL) are two species of the Enterobacteriaceae family causing significant medical concern due to their role in producing numerous opportunistic infections such as bacteremia, lower respiratory tract infections, urinary tract infections, and endocarditis. …

Environmental Changes Turn On The Sinorhizobium Melitloti Exor-Exos/Chvi (Rsi) Host Invasion Switch, Shari N. Walcott

Dissertations, Theses, and Capstone Projects

The free-living Gram-negative soil bacterium, Sinorhizobium meliloti, must switch into its host-invading form in order to infect the root hairs of the host plant, alfalfa (Medicago sativa), and establish a nitrogen-fixing symbiosis. The activation of the switch is believed to occur inside the infection chamber that is formed by curling of the root hairs. It is not fully understood what signals in the environment of the root hairs trigger and infection chamber S. meliloti to switch into a host-invading form since these signals were not extensively examined until now. This switch can be observed directly, due to …

Scanning Labyrinthulomycete Genomes For Yeast Transcription Factor Binding Site Motifs, Jackie L. Collier, Joshua Rest

Interdisciplinary Research Data

To develop broadly useful methods for the genetic manipulation of Labyrinthulomycetes (a diverse group of ubiquitous osmoheterotrophic marine protists), it is essential to understand the similarities and differences in regulation of gene expression among them. Toward this end we have used FIMO from the MEME suite (http://meme-suite.org/doc/fimo.html) to identify potential transcription factor binding sites in each of the three available genome sequences: Aplanochytrium kerguelense PBS07, Schizochytrium aggregatum ATCC 28209, and Aurantiochytrium limacinum ATCC MYA-1381

Proteomic Approach For Extracting Cytoplasmic Proteins From Streptococcus Sanguinis Using Mass Spectrometry, Fadi Elrami, Kristina Nelson, Ping Xu

Philips Institute for Oral Health Research Publications

Streptococcus sanguinis is a commensal and early colonizer of oral cavity as well as an opportunistic pathogen of infectious endocarditis. Extracting the soluble proteome of this bacterium provides deep insights about the physiological dynamic changes under different growth and stress conditions, thus defining “proteomic signatures” as targets for therapeutic intervention. In this protocol, we describe an experimentally verified approach to extract maximal cytoplasmic proteins from Streptococcus sanguinis SK36 strain. A combination of procedures was adopted that broke the thick cell wall barrier and minimized denaturation of the intracellular proteome, using optimized buffers and a sonication step. Extracted proteome was quantitated …

Analysis Of The Prevention Of Biocorrosion Caused By Desulfovibrio Alaskensis G20, Michael Boring

Honors Undergraduate Theses

Desulfovibrio alaskensis G20 and other sulfate-reducing bacteria cause significant damage to metal pipelines and other infrastructure through a metabolic pathway that releases toxic hydrogen sulfide into their surroundings. The biocorrosion that results from the release of hydrogen sulfide creates significant economic burden, and can pose health risks for those exposed to this chemical. They are commonly present in the form of biofilms, an extracellular matrix composed of bacterial cells, polysaccharides, proteins, nucleic acids, and other materials. These biofilms are difficult to remove, and they provide protection to the bacteria within from anti-bacterial treatments. Desulfovibrio alaskensis G20 is a strain derived …

The Development Of New Molecular Tools To Detect Mycobacterium Avium Subspecies Paratuberculosis From A Bovine Faecal Environment By Real-Time Pcr, Marcel De Kruijf

Theses

The slow-growing intracellular pathogen Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease in domesticated and wild ruminants. Johne’s disease inflicts severe annual economic losses to the dairy industry worldwide. This thesis is divided into five chapters that consist of a literature review' chapter and four experimental chapters focusing on MAP strain genotyping and the development of novel molecular MAP detection tools using real-time PCR. Chapter 1 describes published information regarding MAP characteristics, Johne’s disease, MAP genomes, available MAP detection methods, MAP epidemiology and genotyping.

To efficiently control and monitor MAP infection, molecular t>ping of MAP strains provides extensive knowledge …