Bacteriology Commons^™

Antibiotic Efficacy And Interaction In Escherichia Coli During Varying Nutrient Conditions, Kristina K. Millar

Scripps Senior Theses

Due to the recent rise in antibiotic resistant pathogens, and the difficulties surrounding the quest for new antibiotics, many researchers have started revisiting antibiotic interactions in hopes of finding new treatment options. The primary outcome of this project was to examine the efficacy of concomitant antibiotic use under varying nutrient conditions, to identify variations in antibiotic interactions. Antibiotic interactions were studied, utilizing E. coli as a model bacterial system, grown in four different media types. E. coli cultures were treated with streptomycin, tobramycin, erythromycin, and amikacin individually and in a pairwise fashion at varying doses. We found that at least …

Frequency And Etiology Of Community-Acquired Bloodstream Infection In Hospitalized Febrile Children, Tufail Soomro, Shiyam Sunder Tikmani, Sumera Aziz Ali

Community Health Sciences

Background: Blood stream infection is a serious problem that needs immediate attention and treatment. We aim to identify the frequency of common organisms in blood culture of febrile pediatric patients so that empirical antibiotic therapy can be started timely.
Methods: This cross-sectional study was conducted in pediatric ward Civil Hospital Sukkur from 1st May 2013 to 31st October 2014. Children of both genders who are between the age of one month to 15 years admitted to the pediatric ward with a fever of > 38.0 c and with a history of fever ˃ two days and whose blood culture has been …

Anaplasma Marginale Actively Modulates Vacuolar Maturation During Intracellular Infection Of Its Tick Vector, Dermacentor Andersoni, Foregivemore Magunda, Chelsea Wright Thompson, David A. Schneider, Susan M. Noh

Biological Sciences Faculty Publications

ABSTRACT Tick-borne transmission of bacterial pathogens in the order Rickettsiales is responsible for diverse infectious diseases, many of them severe, in humans and animals. Transmission dynamics differ among these pathogens and are reflected in the pathogen-vector interaction. Anaplasma marginale has been shown to establish and maintain infectivity within Dermacentor spp. for weeks to months while escaping the complex network of vacuolar peptidases that are responsible for digestion ofthe tick blood meal. How this prolonged maintenance of infectivity in a potentially hostile environment is achieved has been unknown. Using the natural vector Dermacentor andersoni, we demonstrated that A. marginale …

Screening For Pathogenic Escherichia Coli In The Chattahoochee River, Columbus, Georgia, Micah A. Staples

Theses and Dissertations

Escherichia coli testing is frequently used to indicate the possible presence of harmful pathogens, but E. coli itself can be pathogenic. Serotype 0157:H7, enterohemorrhagic E. coli, is likely the most medically important pathogenic strain of E. coli in the United States. In this study, we surveyed for 0157:H7 and three strains of another pathogenic subtype: enterotoxigenic E. coli. We isolated E. coli colonies from samples taken from the Chattahoochee River in Columbus, Georgia at two different locations, above and below wastewater outputs. We used PCR to test for the individual subtypes and then used a nested PCR protocol …

Toxicity Of Engineered Nanomaterials To Plant Growth Promoting Rhizobacteria, Ricky W. Lewis

Theses and Dissertations--Plant and Soil Sciences

Engineered nanomaterials (ENMs) have become ubiquitous in consumer products and industrial applications, and consequently the environment. Much of the environmentally released ENMs are expected to enter terrestrial ecosystems via land application of nano-enriched biosolids to agricultural fields. Among the organisms most likely to encounter nano-enriched biosolids are the key soil bacteria known as plant growth promoting rhizobacteria (PGPR). I reviewed what is known concerning the toxicological effects of ENMs to PGPR and observed the need for high-throughput methods to evaluate lethal and sublethal toxic responses of aerobic microbes. I addressed this issue by developing high-throughput microplate assays which allowed me …

The Loss Of Methanol Utilization In Methylobacteria, Justin T. Skariah

Theses and Dissertations

Methylobacteria primary uses Cl substrates as a carbon and energy source. This experiment was performed to see if Methylobacteria would lose the ability to use Cl compound methanol after prolonged exposure to multi-carbon substrates. To determine this, the bacteria was grown on MR2A3 (multi-carbon substrates) and MOM (single-carbon substrates) for multiple generations and tested for loss of function on a series of generations. These tests include streaking plates of MOM and R2A with bacteria from MR2A3 then getting a bacterial colony count and also toothpick transfers of the colonies to verify findings. After 20 generations there were no significant decrease …

Inhibition Of Bacterial Growth And Prevention Of Bacterial Adhesion With Localized Nitric Oxide Delivery, Julia Osborne

Dissertations, Master's Theses and Master's Reports

Bacterial infections continue to be a problem at the site of an indwelling medical device, and over the years, various bacterial strains have become more resistant to current antibiotic treatments. Bacterial infection at an indwelling medical device can be dangerous and affect the performance of the medical device which can ultimately lead to the failure of the device due to bacterial resistance to treatment.

Nitric Oxide (NO) has been shown to possess antibacterial properties to prevent and inhibit bacterial growth. NO releasing coatings on indwelling medical devices could provide a reduction in bacterial infections that occur at the device site …

Draft Genome For A Urinary Isolate Of Lactobacillus Crispatus, Travis Kyle Price, Majed Shaheen, Laurynas Kalesinskas, Kema Malki, Evann Elizabeth Hilt, Catherine Putonti, Alan J. Wolfe

Bioinformatics Faculty Publications

While Lactobacillus crispatus contributes to the stability of normal vaginal microbiota, its role in urinary health remains unclear. As part of an on-going attempt to characterize the female urinary microbiota, we report the genome sequence of an L. crispatus strain isolated from a woman displaying no lower urinary tract symptoms.

Determination Of Cyclic-Di-Gmp- Controlled Gene Expression In A Pharmacologically Important Bacterium, Morgan A. Stark

Undergraduate Honors Thesis Projects

The second messenger molecule cyclic dimeric GMP (c-di-GMP) regulates a myriad of processes in gram-negative bacteria. However, less is known about the roles it plays in gram-positive bacteria. Differential gene expression in three strains of the gram-positive bacterium, Streptomyces coelicolor, is being studied using RNA sequencing and Real Time PCR to gain insight into c-di-GMP signaling. The rmdA rmdB (regulator of morphology and development) double mutant was compared to the wild type strain known as MT1110. The rmdA and rmdB genes are needed for the formation of aerial mycelium, an important step in the life cycle of Streptomyces coelicolor (Hull …

Design And Testing Of Novel Anthrax Vaccines Utilizing A Tobacco Mosaic Virus Expression System, Ryan C. Mccomb

KGI Theses and Dissertations

Anthrax is a potentially fatal disease caused by the bacteria Bacillus anthracis. Infection and disease occur after spores gain entry into the body, germinate into vegetative bacteria, and produce toxin. Bacillus anthracis spores have been engineered as bioweapons and have been used repeatedly in warfare and terrorism to inflict casualties in military and civilian populations. Currently, only one vaccine has been approved for prevention of anthrax in the United States. This vaccine is an undefined product that is difficult to produce, requires a long vaccination schedule, and is reactogenic. Efforts to make an improved anthrax vaccine are being pursued. …

Production And Harvest Of Microalgae In Wastewater Raceways With Resource Recycling, Alexander Colin Roberts

Master's Theses

Microalgae can be grown on municipal wastewater media to both treat the wastewater and produce feedstock for algae biofuel production. However the reliability of treatment must be demonstrated, as well as high areal algae productivity on recycled wastewater media and efficient sedimentation harvesting. This processes was studied at pilot scale in the present research.

A pilot facility was operated with nine CO₂-supplemented raceway ponds, each with a 33-m² surface area and a 0.3-m depth, continuously from March 6, 2013 through September 24, 2014. The ponds were operated as three sets of triplicates with two sets continuously fed …

Functional Characterization Of Aggregatibacter Actinomycetemcomitans Qsebc : A Bacterial Adrengeric Receptor And Global Regulator Of Virulence., Whitney Weigel

Electronic Theses and Dissertations

In order for a pathogen to successfully colonize the host, it must be able to acquire essential nutrients and regulate gene expression to respond to environmental fluctuations. One mechanism bacteria have evolved in order to detect these fluctuations and respond is the two component signal transduction systems (TCS). Aggregatibacter actinomycetemcomitans, a dental commensal associated with localized aggressive periodontitis, contains a TCS designated QseBC that was previously shown to regulate expression of several iron acquisition genes, biofilm formation and virulence, but the activating signal was unknown []. QseBC is a conserved TCS in the Enterobacteriaceae and Pasteurellaceae, but the activating signal …

Detection Methods And Intestinal Adherence Of Non-O157 Shiga Toxin-Producing Escherichia Coli, Zachary R. Stromberg

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

Shiga toxin-producing Escherichia coli (STEC) are enteric pathogens of humans. Cattle serve as a reservoir and harbor STEC in their intestines. Intimin-positive STEC are referred to as enterohemorrhagic E.coli (EHEC). Seven serogroups (O26, O45, O103, O111, O121, O145, and O157) account for the majority of illness due to STEC and are hereafter referred to as STEC/EHEC-7. To improve detection, enrichment broths were compared for supporting growth of STEC-7 and STEC O104:H4 (STEC-8). In pure culture, STEC enriched in trypticase soy broth (TSB) had significantly greater growth compared to TSB containing antimicrobials. In fecal samples, E. coli broth enrichment yielded …

Cyclic Di-Gmp-Mediated Repression Of Swarming Motility By Pseudomonas Aeruginosa Pa14 Requires The Motab Stator, S. L. Kuchma, N. J. Delalez, L. M. Filkins, E. A. Snavely, J. P. Armitage, G. A. O'Toole

Dartmouth Scholarship

The second messenger cyclic diguanylate (c-di-GMP) plays a critical role in the regulation of motility. In Pseudomonas aeruginosa PA14, c-di-GMP inversely controls biofilm formation and surface swarming motility, with high levels of this dinucleotide signal stimulating biofilm formation and repressing swarming. P. aeruginosa encodes two stator complexes, MotAB and MotCD, that participate in the function of its single polar flagellum. Here we show that the repression of swarming motility requires a functional MotAB stator complex. Mutating the motAB genes restores swarming motility to a strain with artificially elevated levels of c-di-GMP as well as stimulates swarming in the wild-type strain, …

A Tail Of Two Phages: Genomic And Functional Analysis Of Listeria Monocytogenes Phages Vb_Lmos_188 And Vb_Lmos_293 Reveal The Receptor-Binding Proteins Involved In Host Specificity, Aidan Casey, Kieran Jordan, Horst Neve, Aidan Coffey, Olivia Mcauliffe

Department of Biological Sciences Publications

The physical characteristics of bacteriophages establish them as viable candidates for downstream development of pathogen detection assays and biocontrol measures. To utilize phages for such purposes, a detailed knowledge of their host interaction mechanisms is a prerequisite. There is currently a wealth of knowledge available concerning Gram-negative phage-host interaction, but little by comparison for Gram-positive phages and Listeria phages in particular. In this research, the lytic spectrum of two recently isolated Listeria monocytogenes phages (vB_LmoS_188 and vB_LmoS_293) was determined, and the genomic basis for their observed serotype 4b/4e host-specificity was investigated using comparative genomics. The late tail genes of these …

Isolation & Characterization Of Bacteria In The Built Environment: Measuring The Effect Of Pharmaceuticals On Growth, Amanda V. Finck, Kelly J. Digeronimo, Nene S. Sy, Zakiya Whatley

Student Publications

This work reports the isolation and characterization of bacteria from the built environment at Gettysburg College in Gettysburg, PA. Surfaces of a water fountain on campus were swabbed and serially streaked to isolate multiple bacteria on R2A agar. Following multiple rounds of growth, the unknown microbial candidates were narrowed to two visibly­distinct organisms. Morphological characterization and phylogenetic identification based on 16S rDNA sequencing revealed that the isolates were Chryseobactierum hispalense and Microbacterium maritypicum. We report synergistic biofilm formation between Chryseobactierum hispalense and Microbacterium maritypicum. The contamination of drinking water with varying levels of personal care products and pharmaceuticals (PCPPs) is …

How Many Particles Are Present In The Air? Bioaerosol Detection Using An Air Particle Counter, Angie Pamela Rivera, Parag Vaishampayan

STAR Program Research Presentations

Relative cleanliness in terms of particle abundance in spacecraft assembly facilities is determined by particle counts carried out in clean rooms during resting conditions. Particle counters assess total particles and particle size distribution, but do not distinguish inert particles from biological particles, which may include bacterial spores that are resistant to standard cleanroom sterilization procedures. Current cleanroom certifications do not fully assess the effects of human presence on spacecraft contamination since humans are known symbionts to enumerate microorganisms and assessments are performed at rest when there is no human presence. In this study, contamination risks and bioburden in spacecraft assembly …

Collecting Diverse Microorganisms From Rover Spacecraft, Jennifer I. Jacobs, Arianna Jefferson, Heidi Aronson, James Tan, Wayne Schubert, Parag Vaishampayan

STAR Program Research Presentations

. The Planetary Protection discipline at NASA’s Jet Propulsion Laboratory develops and implements procedures to prevent both forward and backward contamination between the Earth and solar system bodies. However, there will always be some microorganisms that will be resistant to the strictest of sterilization methods. In order understand the microorganisms found on spacecraft during assembly, and to rapidly identify them, a mass spectrometry approach was developed. As an experimental approach, a custom database was created for a subset of microorganisms in the Planetary Protection Archive. In order to make the database as accurate and efficient as possible, several different procedures …

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. …

Identification Of Genes Required To Synthesize An Antibiotic-Like Compound From The Soil Bacterium Rhodococcus Sp. Mtm3w5.2, Amber L. Ward

Electronic Theses and Dissertations

Rhodococcus is a soil bacterium, member of the Actinobacteria, and a close relative of the prolific small molecule producer Streptomyces. Recent interest in Rhodococcus as an under investigated source of possible bioactive secondary metabolites is sparked by the discovery of many polyketide synthase and non-ribosomal peptide synthetase genes of unknown function from sequenced Rhodococcus genomes. Rhodococcus species strain MTM3W5.2 was recently shown to produce a strong inhibitory compound with activity against most strains of Rhodococcus and closely related genera. A goal of this investigation is to discover the gene(s) required to synthesize this inhibitory molecule. The engineered Rhodococcus …

Algr Directly Controls Rsma In Pseudomonas Aeruginosa, Tyler Speaks

Electronic Theses and Dissertations

Pseudomonas aeruginosa is a bacterial pathogen that can infect any human tissue. The lungs of cystic fibrosis patients become chronically infected with Pseudomonas aeruginosa. Virulence factor gene expression is under elaborate regulatory control that remains poorly characterized. Understanding the regulatory hierarchy involved during infection is essential for identifying novel drug targets. RsmA is a post-transcriptional regulatory protein that controls expression of several virulence factors. Previous studies demonstrated alginate regulatory components AlgU and AlgR as regulators of rsmA expression. The aim of this study was to determine how AlgR controls rsmA expression. Western blot analysis of HA-tagged RsmA confirmed lower …

Inhibition Of Cell Differentiation In Bacillus Subtilis By Pseudomonas Protegens, Matthew J. Powers, Edgardo Sanabria-Valentín, Albert A. Bowers, Elizabeth A. Shanka

Publications and Research

Interspecies interactions have been described for numerous bacterial systems, leading to the identification of chemical compounds that impact bacterial physiology and differentiation for processes such as biofilm formation. Here, we identified soil microbes that inhibit biofilm formation and sporulation in the common soil bacterium Bacillus subtilis. We did so by creating a reporter strain that fluoresces when the transcription of a biofilm-specific gene is repressed. Using this reporter in a coculture screen, we identified Pseudomonas putida and Pseudomonas protegens as bacteria that secrete compounds that inhibit biofilm gene expression in B. subtilis. The active compound produced by P. protegens was …

Deletion Of Nfnab In Thermoanaerobacterium Saccharolyticum And Its Effect On Metabolism, Jonathan Lo, Tianyong Zheng, Daniel G. Olson, Natalie Ruppertsberger, Shital Tripathi, Adam Guss, Lee Lynd

Dartmouth Scholarship

NfnAB catalyzes the reversible transfer of electrons from reduced ferredoxin and NADH to 2 NADP⁺. The NfnAB complex has been hypothesized to be the main enzyme for ferredoxin oxidization in strains of Thermoanaerobacterium saccharolyticum engineered for increased ethanol production. NfnAB complex activity was detectable in crude cell extracts of T. saccharolyticum. Activity was also detected using activity staining of native PAGE gels. The nfnAB gene was deleted in different strains of T. saccharolyticum to determine its effect on end product formation. In wild-type T. saccharolyticum, deletion of nfnAB resulted in a 46% increase in H₂ formation but …

Prokaryotic Diversity In The Rhizosphere Of Organic, Intensive, And Transitional Coffee Farms In Brazil, Adam Caldwell, Livia Silva, Cynthia Da Silva, Cleber Ouverney

Faculty Publications, Biological Sciences

Despite a continuous rise in consumption of coffee over the past 60 years and recent studies showing positive benefits linked to human health, intensive coffee farming practices have been associated with environmental damage, risks to human health, and reductions in biodiversity. In contrast, organic farming has become an increasingly popular alternative, with both environmental and health benefits. This study aimed to characterize and determine the differences in the prokaryotic soil microbiology of three Brazilian coffee farms: one practicing intensive farming, one practicing organic farming, and one undergoing a transition from intensive to organic practices. Soil samples were collected from 20 …

Secretion Of Heat-Labile Enterotoxin By Porcine-Origin Enterotoxigenic Escherichia Coli And Relation To Virulence, Prageeth Rukshan Wijemanne

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

Heat-labile enterotoxin (LT) is an important virulence factor secreted by some strains of porcine-origin enterotoxigenic Escherichia coli (pETEC). The prototypic human-origin strain H10407 secretes LT via a type II secretion system (T2SS), but its presence or importance in pETEC has not been established. Exposure of pETEC to glucose has been shown to result in different secretion levels of LT. Furthermore, the relationship between the level of LT secreted and the virulence potential of the respective pETEC strain has not been established. To determine the relationship between the capacity to secrete LT and virulence in wild-type (WT) pETEC, 16 strains isolated …

Cofactor Specificity Of The Bifunctional Alcohol And Aldehyde Dehydrogenase (Adhe) In Wild-Type And Mutant Clostridium Thermocellum And Thermoanaerobacterium Saccharolyticum, Tianyong Zheng, Daniel G. Olson, Liang Tian, Yannick J. Bomble, Michael Himmel, Jonathan Lo, Shuen Hon, A. Joe Shaw, Johannes P. Van Dijken, Lee Lynd

Dartmouth Scholarship

Clostridium thermocellum and Thermoanaerobacterium saccharolyticum are thermophilic bacteria that have been engineered to produce ethanol from the cellulose and hemicellulose fractions of biomass, respectively. Although engineered strains of T. saccharolyticum produce ethanol with a yield of 90% of the theoretical maximum, engineered strains of C. thermocellum produce ethanol at lower yields (∼50% of the theoretical maximum). In the course of engineering these strains, a number of mutations have been discovered in their adhE genes, which encode both alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) enzymes. To understand the effects of these mutations, the adhE genes from six strains of C. …

The C-Terminal Linker Of Ftsz Acts As An Intrinsically Disordered Peptide During Cell Division In Bacillus Subtilis, Steven Grigsby

Undergraduate Theses—Unrestricted

The bacterial tubulin homologue FtsZ polymerizes in vitro in a GTP-dependent manner to form long, single stranded filaments. In cells, these filaments assemble at the nascent division site, interacting laterally to form the contractile Z ring. The Z ring serves as a scaffold for the rest of the division machinery and constricts at the leading edge of the invaginating septum during cytokinesis. The FtsZ polypeptide consists of three primary domains: the N-terminal globular core consisting of 315 residues that contains the GTP binding site, a variable and flexible C-terminal linker (CTL) consisting of 50 residues, and a conserved region at …

Transduction As The Method Of Horizontal Gene Transfer Of The Staphylococcal Chromosomal Cassette Mec (Sccmec), Amber B. Sauder

Senior Honors Projects, 2010-2019

Methicillin-resistant Staphylococcus aureus (MRSA) gains resistance to β-lactam antibiotics through a mutated penicillin binding protein (PBP2a) encoded on the SCCmec element. In combination with the recombinase encoded by ccr, these two genes are used as markers of the mobile genetic element (SCCmec). Due to recent increases in community acquired MRSA infections, the mechanisms of antibiotic resistance gene transfer have gained attention. Transduction, a method of horizontal gene transfer mediated by bacteriophage, is believed to be responsible for the movement of the SCCmec element. Recent studies have shown the transduction of the SCCmec element in clinical isolates; however, this study is …

Comparative Analysis Of Anti-Bd Bacteria From Six Malagasy Frog Species Of Ranomafana National Park, Kelsey Savage

Senior Honors Projects, 2010-2019

As Malagasy amphibians are facing an impending extinction crisis from the lethal skin fungus Batrachochytrium dendrobatidis (Bd), it has become imperative to proactively mitigate the threat. Bd sporangia develop in the skin of infected amphibians and cause the skin to thicken, leading to ionic imbalance and eventual heart failure. It has been shown that certain bacterial species are able to inhibit Bd growth on amphibians by producing antifungal metabolites. Community-based probiotics are one approach used to combat chytridomycosis by inoculating an environment with Bd-inhibitory bacteria so that many amphibian species are treated at once. With this method, it is important …

Tonb Not Directly Related To Efflux Of Antibiotics In E. Coli, Amber Gombash

Honors Projects

Studies in Pseudomonas aeruginosa have suggested that the TonB energy transduction system directly contributes to efflux-mediated antibiotic resistance, ostensibly by energizing one or more efflux systems. We have found ∆tonB strains of Escherichia coli to similarly be more sensitive to certain antibiotics relative to wild-type strains. To test the hypothesis that this enhanced sensitivity involved the energization of efflux systems, sensitivity patterns for a variety of antibiotics were evaluated using a set of strains differentially lacking genes encoding the Acr efflux system, the universal outer membrane efflux portal TolC, and TonB. No correlation was evident between the resistance phenotypes of …