Microbiology Commons^™

The “Big Six”: Hidden Emerging Foodborne Bacterial Pathogens, Mona G. Alharbi, Rashad R. Al-Hindi, Ahmed Esmael, Ibrahim A. Alotibi, Sheren A. Azhari, Mazen S. Alseghayer, Addisu D. Teklemariam

Nebraska Center for Virology: Faculty Publications

Non-O157 Shiga toxin-producing Escherichia coli (STEC) are emerging serogroups that often result in diseases ranging from diarrhea to severe hemorrhagic colitis in humans. The most common non-O157 STEC are O26, O45, O103, O111, O121, and O145. These serogroups are known by the name “big six” because they cause severe illness and death in humans and the United States Department of Agriculture declared these serogroups as food contaminants. The lack of fast and efficient diagnostic methods exacerbates the public impact of the disease caused by these serogroups. Numerous outbreaks have been reported globally and most of these outbreaks were caused by …

Qualitative Proteomic And Genomic Analysis Of Klebsiella Pneumoniae Bacteriophage Kaomega, Emilee Carr

Undergraduate Honors Theses

Klebsiella pneumoniae is a Gram-negative Enterobacteriaceae that is a common nosocomial pathogen causing pneumonia, infections in the bloodstream, wound infections, and meningitis. It has developed natural resistance to multiple antibiotics, most notably carbapenems which are often seen as the last line of defense against multi-drug resistant pathogens. Bacteriophages are being investigated as a promising alternative treatment to antibiotics in fighting these resistant pathogens. KaOmega, a Klebsiella pneumoniae bacteriophage, was isolated, sequenced, and annotated to characterize and understand its potential for use in a phage therapy. Characterization included Phyre2 analysis to predict putative protein functions based on structural homology, burst size …

Assessment Of Bacteriological Quality Of Drinking Water In Some Primary And Secondary Schools In Mukalla City-Hadhramout/Yemen, Eidha Ali Bin Hameed, Khaled Saleh Bin Alshikh Bubkr

Hadhramout University Journal of Natural & Applied Sciences

Assessment of faecal contamination and detection enumeration of coliforms and other microorganisms in water is one of the measurements to determine the hygienic quality of water. This study aimed to assess the drinking water in some primary and secondary schools in Mukalla city-Hadhramout/Yemen to estimate the bacterial contamination of drinking water and its safety to the public. The water samples were studied for bacteriological analysis in which was inoculated into culture media using two methods, the presumptive test for the most probable number (MPN) and confirmatory test for bacterial identification. Also, some physiochemical properties of water such as temperature, total …

Prevalence And Multidrug Resistance Pattern Of E. Coli Among Urinary Tract Infection Patients In Tertiary Care Hospital Of Multan, Hubza Ruatt Khan, Mehvish Javeed, Asghar Javed, Nisma Farooq

Journal of Bioresource Management

Urinary Tract Infection is alarming problem worldwide due to the intensity of antimicrobial resistance. Escherichia coli is the most predominant organism in UTI. This study was planned to evaluate demographic parameters, the prevalence of E. coli, and antimicrobial resistance patterns among E. coli isolates from UTI patients in Nishtar Hospital of Multan from January to June 2018. A total of 350 mid-stream urine samples were collected from different patients having age group from 25 to 60 years and processed by standard laboratory procedures. Out of 350 samples, 100 samples were observed as critical bacteremia. Escherichia coli and Klebsiella …

Copper-Mediated Regulation Of A Traditional Iron Uptake System In Uropathogenic Escherichia Coli., George Lwanga Katumba

Arts & Sciences Electronic Theses and Dissertations

Transition metals constitute an important part of the host-pathogen interface. Iron is an essential nutrient that functions as a cofactor for numerous bacterial and host proteins, as either a ligand for oxygen in carrier proteins or an enzyme catalytic site due to its natural redox properties. As part of the innate immune response, infected hosts sequester iron from pathogens to limit their growth, a phenomenon known as nutritional immunity. On the other hand, copper ions are deployed at infection sites as a potent antimicrobial agent to kill bacteria. The ability to survive within multiple, often harsh, microenvironments is fundamental to …

The Ability Of Lactobacillus Spp. To Limit Extracellular Atp Release By Urogenital Bacteria, Hannah Wilcox

Electronic Thesis and Dissertation Repository

Urgency urinary incontinence is a common symptom of overactive bladder (OAB) and urinary tract infection (UTI), which can be triggered by extracellular adenosine triphosphate (eATP) through purinergic signaling. Current treatments for OAB and UTI fail to consider the potential impact of eATP. It is hypothesizes that certain commensal Lactobacillus spp. can modulate levels of eATP released by pathogenic bacteria. This project examined bacterial modulation of eATP during growth, the impact of prebiotics on lactobacilli growth, and studied its reduction in an in vitro bladder infection model. Release and uptake of ATP by a range of commensal and pathogenic bacteria was …

Sensitivity Of Wild-Type And Rifampicin-Resistant O157 And Non-O157 Shiga Toxin-Producing Escherichia Coli To Elevated Hydrostatic Pressure And Lactic Acid In Ground Meat And Meat Homogenate, Abimbola Allison, Aliyar Cyrus Fouladkhah

Agricultural and Environmental Sciences Faculty Research

Various serogroups of Shiga toxin-producing Escherichia coli have been epidemiologically associated with foodborne disease episodes in the United States and around the globe, with E. coli O157: H7 as the dominant serogroup of public health concern. Serogroups other than O157 are currently associated with about 60% of Shiga toxin-producing E. coli related foodborne illness episodes. Current study evaluated sensitivity of the O157 and epidemiologically important non-O157 serogroups of the pathogen to elevated hydrostatic pressure and 1% lactic acid. Pressure intensity of 250 to 650 MPa were applied for 0 to 7 min for inactivation of strain mixtures of …

Incidence Of Antibiotic Resistance And Plasmid Content In Freshwater Beach Sand And Water And Clinical Urinary Tract Infection Escherichia Coli Isolates, Robert F. White

Biology Theses

Antibiotic-resistant (AR) bacteria have been found in environmental ecosystems including beach sand and water, and pose a serious threat to the mitigation of human and animal disease. The presence of antibiotic residues in the environment, fueled by wastewater effluent and agricultural runoff, may produce selective pressure on introduced microbes such as Escherichia coli, leading to the production of AR populations. This study characterized and compared the antibiotic resistance patterns and plasmid content of E. coli isolated from a freshwater beach and clinical urinary tract infection (UTI) samples. A higher level of antibiotic resistance was expected in clinical (UTI) Escherichia coli …

A Mini-Tn5-Derived Transposon With Reportable And Selectable Markers Enables Rapid Generation And Screening Of Insertional Mutants In Gram-Negative Bacteria, Eric S. Nazareno, Bimala Acharya, C. Korsi Dumenyo

Agricultural and Environmental Sciences Faculty Research

We re-engineered a classic tool for mutagenesis and gene expression studies in Gram-negative bacteria. Our modified Tn5-based transposon contains multiple features that allow rapid selection for mutants, direct quantification of gene expression and straightforward cloning of the inactivated gene. The promoter-less gfp-km cassette provides selection and reporter assay depending on the activity of the promoter upstream of the transposon insertion site. The cat gene facilitates positive antibiotic selection for mutants, while the narrow R6Kγ replication origin forces transposition in recipient strains lacking the pir gene and enables cloning of the transposon flanked with the disrupted gene from the chromosome. The …

Histidine-Triad Hydrolases Provide Resistance To Peptide-Nucleotide Antibiotics., Eldar Yagmurov, Darya Tsibulskaya, Alexey Livenskyi, Marina Serebryakova, Yury I Wolf, Sergei Borukhov, Konstantin Severinov, Svetlana Dubiley

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

The Escherichia coli microcin C (McC) and related compounds are potent Trojan horse peptide-nucleotide antibiotics. The peptide part facilitates transport into sensitive cells. Inside the cell, the peptide part is degraded by nonspecific peptidases releasing an aspartamide-adenylate containing a phosphoramide bond. This nonhydrolyzable compound inhibits aspartyl-tRNA synthetase. In addition to the efficient export of McC outside the producing cells, special mechanisms have evolved to avoid self-toxicity caused by the degradation of the peptide part inside the producers. Here, we report that histidine-triad (HIT) hydrolases encoded in biosynthetic clusters of some McC homologs or by standalone genes confer resistance to McC-like …

Regulation Of Acetyl Phosphate-Dependent Acetylation And Identification Of Novel Lysine Acetyltransferases In Escherichia Coli, David George Christensen

Dissertations

Over billions of years, organisms have organized chemical reactions into metabolic pathways to sustain life. However, metabolic substrates can undergo many uncatalyzed, extra-metabolic reactions. Acetyl phosphate (AcP), an intermediate of the acetate fermentation pathway in E. coli, is one such metabolite that has been shown to non-enzymatically acetylate hundreds of proteins. This diverse set of targets suggests that acetylation could be a way for the cell to sense its nutritional status and regulate protein activity accordingly. However, how E. coli regulates acetylation, if at all, is unknown.Previous work showed that acetylation becomes pronounced in stationary phase cells. I determined that …

Premature Rho-Dependent Transcription Termination In Escherichia Coli : Link To Translation And Gene Regulation, Gabriele Baniulyte

Legacy Theses & Dissertations (2009 - 2024)

Transcription termination factor Rho is an essential protein in Escherichia coli and related bacteria. The primary function of Rho is to clear unproductive RNA polymerases from the DNA template to minimize negative effects associated with uncontrolled transcription. Although most of the Rho termination events are constitutive, premature Rho-mediated termination was observed at 3% of all affected transcripts indicating active regulation of Rho activity. In this work, we investigated the regulatory mechanism behind premature Rho-dependent transcription termination in two unrelated genes: suhB and topAI. We show that in both cases transcription is terminated inside the coding gene as a consequence of …

Post-Translational Modifications And Functional Studies Of Dksa In Escherichia Coli, Andrew Charles Isidoridy

Legacy Theses & Dissertations (2009 - 2024)

DksA is a bacterial gene regulator that functions synergistically with the stress alarmone ppGpp to mediate the stringent response. DksA also functions independently of ppGpp to regulate transcription of a number of genes. DksA function is dependent on its binding affinity to RNA polymerase and requires specific interactions between RNAP and catalytic amino acids located on the coiled coil tip, D74 and A76. While much of the previous work on DksA has focused on understanding the mechanisms of action and the numerous gene targets for transcriptional regulation, little is known about the mechanisms by which DksA expression and function may …

Transcriptional Regulation Of Dksa In E. Coli, Daniel Thomas Woods

Legacy Theses & Dissertations (2009 - 2024)

DksA is a global transcription factor that binds RNAP directly to regulate the expression of many genes and operons, including ribosomal RNA, in a ppGpp-dependent or ppGpp–independent manner. It is also involved in facilitating the process of DNA replication by removing stalled transcription elongation complexes that could block the progress of the replication fork. In addition, DksA is important for colonization, establishment of biofilms, and pathogenesis. In order to sustain these various functions, an adequate level of cellular DksA is required. This work tested the hypothesis that the E. coli dksA is substantially regulated at the level of transcription. Using …

Investigating The Single Cell Heterogeneity And Physiological Impact Of Mistranslation, Christopher Evans

Dissertations & Theses (Open Access)

Bacterial populations grow clonal populations; however, individual cells have a variety of phenotypes. The physiological heterogeneity observed in populations has been attributed to variations in the processes of gene expression. For example, promoter expression has been shown to be heterogeneous within a population and contribute to increased stress tolerance in a subpopulation of cells. In comparison to transcription, the influence of translation on single cells is unclear. In this study, my collaborators and I have developed a dual-fluorescence reporter that allows us to measure the mistranslation rate in single cells in vivo. Using this reporter, we found that mistranslation …

A Recurrent Silent Mutation Implicates Feca In Ethanol Tolerance By Escherichia Coli., Katherine M Lupino, Kymberleigh A Romano, Matthew J Simons, John T Gregg, Leanna Panepinto, Ghislaine M Cruz, Lauren Grajek, Gregory A. Caputo, Mark J. Hickman, Gregory B. Hecht

Faculty Scholarship for the College of Science & Mathematics

BACKGROUND: An issue associated with efficient bioethanol production is the fact that the desired product is toxic to the biocatalyst. Among other effects, ethanol has previously been found to influence the membrane of E. coli in a dose-dependent manner and induce changes in the lipid composition of the plasma membrane. We describe here the characterization of a collection of ethanol-tolerant strains derived from the ethanologenic Escherichia coli strain FBR5.

RESULTS: Membrane permeability assays indicate that many of the strains in the collection have alterations in membrane permeability and/or responsiveness of the membrane to environmental changes such as temperature shifts or …

Cloning And Functional Analysis Of The Escherichia Coli Cell Division Protein Zape, Katherine Kellenberger

Senior Honors Projects

During bacterial cell division, a large, dynamic cytoskeletal structure called the Z-ring assembles at the site of division. The Z-ring is comprised of the major cell division protein FtsZ, a tubulin-like GTPase that utilizes GTP to assemble into linear polymers. In Escherichia coli, there are several cell division proteins that interact with FtsZ and regulate Z-ring assembly, constriction, and disassembly. The accessory proteins that interact with FtsZ are called Z-ring associated proteins (ZAPs). The Zaps which include ZapA, ZapB, ZapC, ZapD and ZapE are recruited to the divisome and influence Z-ring assembly and stability. Specifically, ZapE was identified to be …

An Analysis Of Between-Cow Variation In Innate Immunity In Relation To Mastitis Severity, Filiz Korkmaz

Graduate College Dissertations and Theses

Bovine mastitis remains one of the costliest diseases affecting the dairy industry. Individual susceptibility to mastitis and severity of infection varies between animals and can only be partially explained by genetics. As such, understanding how genetic predisposition coordinately interacts with epigenetic modifications and environmental exposures is necessary to bridge the gap in missing heritability. The role of DNA methylation in regulating the response to bacterial lipopolysaccharide (LPS) was first determined by performing reduced representation bisulfite sequencing on fibroblasts isolated from heifers at 5- and 16-months of age that exhibit an age-dependent up-regulation in LPS-responsiveness. More than 14,000 differentially methylated sites …

The Role Of Genomic Versatility In Multi-Niche Preferences Of Escherichia Coli, Gitanjali Nandakafle

Electronic Theses and Dissertations

Escherichia coli strains are naturally present as either commensals or pathogens in the gastrointestinal tract of mammals and some other vertebrates. Until recently, it was assumed that E. coli are solely associated with the gut and are unable to survive outside of a host for a long period of time, the basis of its use as an indicator organism. Recent reports suggest that E. coli can become naturalized to several tropical, subtropical or temperate soils and aquatic environments, where they have been isolated repeatedly. Several studies have shown that these strains are capable of surviving and proliferating in the environment …

Genome Sequences And Annotation Of Two Urinary Isolates Of E. Coli, Travis Kyle Price, Arya Mehtash, Laurynas Kalesinskas, Kema Malki, Evann Elizabeth Hilt, Catherine Putonti, Alan J. Wolfe

Catherine Putonti

The genus Escherichia includes pathogens and commensals. Bladder infections (cystitis) result most often from colonization of the bladder by uropathogenic E. coli strains. In contrast, a poorly defined condition called asymptomatic bacteriuria results from colonization of the bladder with E. coli strains without symptoms. As part of an on-going attempt to identify and characterize the newly discovered female urinary microbiota, we report the genome sequences and annotation of two urinary isolates of E. coli: one (E78) was isolated from a female patient who self-reported cystitis; the other (E75) was isolated from a female patient who reported that she did not …

Are Cdi Systems Multicolored, Facultative, Helping Greenbeards?, Elizabeth S. Danka, Erin C. Garcia, Peggy A. Cotter

Microbiology, Immunology, and Molecular Genetics Faculty Publications

Competitive and cooperative interactions between organisms, including bacteria, can significantly impact the composition of a community and the fitness of its members, as well as the fitness of their hosts when communities are living on or within other organisms. Understanding the underlying mechanisms is critical to the development of strategies to control microbiological communities that impact animal and plant health and also for understanding the evolution of social behaviors, which has been challenging for evolutionary biologists. Contact-dependent growth inhibition (CDI) is a phenomenon defined by the delivery of a protein toxin to the cytoplasm of neighboring bacteria upon cell–cell contact, …

Genomic Analysis Of Factors Associated With Low Prevalence Of Antibiotic Resistance In Extraintestinal Pathogenic Escherichia Coli Sequence Type 95 Strains, Craig M. Stephens, Sheila Adams-Sapper, Manraj Sekhon, James R. Johnson, Lee W. Riley

Biology

Extraintestinal pathogenic Escherichia coli (ExPEC) strains belonging to multilocus sequence type 95 (ST95) are globally distributed and a common cause of infections in humans and domestic fowl. ST95 isolates generally show a lower prevalence of acquired antimicrobial resistance than other pandemic ExPEC lineages. We took a genomic approach to identify factors that may underlie reduced resistance. We fully assembled genomes for four ST95 isolates representing the four major fimH-based lineages within ST95 and also analyzed draft-level genomes from another 82 ST95 isolates, largely from the western United States. The fully assembled genomes of antibiotic-resistant isolates carried resistance genes exclusively on …

Mutagenic And Spectroscopic Investigation Of Ph Dependent Cooa Dna Binding, Brian R. Weaver

Chemistry Honors Papers

The carbon monoxide (CO) sensing heme protein, CooA, is a transcription factor which exists in several bacteria that utilize CO as an energy source. CooA positively regulates the expression of coo genes in the presence of CO such that the corresponding proteins may metabolize CO. The present studies have yielded the unexpected result that Fe(III) CooA binds DNA tightly at pH < 7, deviating from all previously reported work which indicate that CooA DNA binding is initiated only when the exogenous CO effector reacts with the Fe(II) CooA heme. This observation suggests that the disruption of one or more salt bridges upon effector binding may be a critical feature of the normal CooA activation mechanism. To test this possibility, several protein variants that eliminated a selected salt bridge for the CooA homolog from Rhodospirillum rubrum were prepared via site-directed mutagenesis. Samples of these variant proteins, which were overexpressed in Escherichia coli, were then characterized by spectroscopic methods and functional assays to investigate the impact these mutations had on CooA heme coordination …

Computing And Applying Atomic Regulons To Understand Gene Expression And Regulation, Jose P. Faria, James J. Davis, Janaka N. Edirisinghe, Ronald C. Taylor, Pamela B. Weisenhorn, Robert D. Olson, Rick Stevens, Miguel Rocha, Isabel Rocha, Aaron A. Best, Matthew Dejongh, Nathan L. Tintle, Bruce Parrelo, Ross Overbeek, Christopher S. Henry

Faculty Work Comprehensive List

Understanding gene function and regulation is essential for the interpretation prediction and ultimate design of cell responses to changes in the environment. An important step toward meeting the challenge of understanding gene function and regulation is the identification of sets of genes that are always co-expressed. These gene sets Atomic Regulons ARs represent fundamental units of function within a cell and could be used to associate genes of unknown function with cellular processes and to enable rational genetic engineering of cellular systems. Here we describe an approach for inferring ARs that leverages large-scale expression data sets gene context and functional …

Genome Sequences And Annotation Of Two Urinary Isolates Of E.Coli, Travis Kyle Price, Arya Mehtash, Laurynas Kalesinskas, Kema Malki, Evann Elizabeth Hilt, Catherine Putonti, Alan J. Wolfe

Bioinformatics Faculty Publications

The genus Escherichia includes pathogens and commensals. Bladder infections (cystitis) result most often from colonization of the bladder by uropathogenic E. coli strains. In contrast, a poorly defined condition called asymptomatic bacteriuria results from colonization of the bladder with E. coli strains without symptoms. As part of an on-going attempt to identify and characterize the newly discovered female urinary microbiota, we report the genome sequences and annotation of two urinary isolates of E. coli: one (E78) was isolated from a female patient who self-reported cystitis; the other (E75) was isolated from a female patient who reported that she did …

Contribution Of A Putative Up Element Dna Sequence To The Activity Of A Newly Identified Phage Promoter, Courtney Hamilton

Mahurin Honors College Capstone Experience/Thesis Projects

In transcription, a universal step in gene expression, information from a DNA sequence is copied into RNA. A key component in gene expression is the promoter sequence, a region of DNA to which RNA polymerase binds during the initiation of transcription of downstream genes. Most bacterial promoters contain a -10 and a -35 sequence that are bound by the RNA polymerase. Some promoters also contain an Upstream Promoter (UP) element. UP elements have been shown to boost promoter activity. We recently identified a new promoter in a mutant bacteriophage that grows on a bacterial host that prevents antitermination of phage …

Assessing Stress Responses To Atmospheric Cold Plasma Exposure Using Escherichia Coli Knock Out Mutants, Lu Han, Daniela Boehm, Sonal Patil, Patrick Cullen, Paula Bourke

Articles

Aim: This study investigated the effect of Atmospheric cold plasma (ACP) exposure induced stress on microbial inactivation patterns and the regulation of genes involved in the microbial stress response in conjunction with key processing parameters of exposure time and post treatment storage time.

Methods and Results: Cell suspensions of Escherichia coli BW 25113 and its isogenic knock-out mutants in rpoS, soxR, soxS, oxyR and dnaK genes were treated with high voltage ACP in a sealed package for 1, 3 and 5 min followed by 0, 1 and 24 h post-treatment storage. ROS densities and colony formation were …

Use Of Energy Healing Medicine Against Escherichia Coli For Antimicrobial Susceptibility, Biochemical Reaction And Biotyping, Mahendra Kumar Trivedi, Alice Branton, Dahryn Trivedi, Gopal Nayak, Mayank Gangwar, Snehasis Jana

Mahendra Kumar Trivedi

Investigation Of Biofield Treatment On Antimicrobial Susceptibility, Biochemical Reaction Pattern And Biotyping Of Enteropathogenic Multidrug-Resistant Escherichia Coli Isolates, Mahendra Kumar Trivedi, Alice Branton, Dahryn Trivedi, Gopal Nayak, Harish Shettigar, Mayank Gangwar, Snehasis Jana

Mahendra Kumar Trivedi

Thermal Inactivation Of Shiga Toxin-Producing Escherichia Coli In Foods, Malcond David Valladares

Doctoral Dissertations

Emerging non-O157 Shiga toxin-producing Escherichia coli (STEC) were recently added to the zero tolerance policy by the USDA-FSIS. Therefore, the precise characterization of their thermal inactivation kinetics in different foods and the effect of stress on thermal inactivation are needed. This research aimed at determining the heat inactivation kinetics of non-O157 and O157 STECs in buffer and model food matrices and the effects of DnaK levels on thermal resistance after acid and heat-shock. Thermal inactivation was carried out in either in 2-ml glass vials or nylon vacuum-sealed bags for buffer and food (spinach, ground-beef, turkey deli-meat, pasta) samples, respectively. Vials …