Bacteriology Commons^™

Microbe Hunters, Paul De Kruif

Zea E-Books Collection

Microbe Hunters by Paul de Kruif was first published in 1926 by Harcourt, Brace and Company, New York. It dramatically recounts the breakthrough discoveries of the fundamental elements of bacteriology. It features exciting profiles of Antony Leeuwenhoek, Lazzaro Spallanzani, Louis Pasteur, Robert Koch, Émile Roux, Emil Behring, Élie Metchnikoff, Theobald Smith, David Bruce, Ronald Ross, Battista Grassi, Walter Reed, and Paul Ehrlich. Their development of germ theory and its scientific proofs led to the first effective treatments for human diseases like anthrax, rabies, diptheria, malaria, sleeping sickness, syphilis, and yellow fever. They also made discoveries that saved the dairy, wine, …

3d Printing Of Human Microbiome Constituents To Understand Spatial Relationships And Shape Parameters In Bacteriology, Jacques Izard, Teklu Kuru Gerbaba, Shara R. P. Yumul

Department of Food Science and Technology: Faculty Publications

Effective laboratory and classroom demonstration of microbiome size and shape, diversity, and ecological relationships is hampered by a lack of high-resolution, easy-to-use, readily accessible physical or digital models for use in teaching. Three-dimensional (3D) representations are, overall, more effective in communicating visuospatial information, allowing for a better understanding of concepts not directly observable with the unaided eye. Published morphology descriptions and microscopy images were used as the basis for designing 3D digital models, scaled at 20,000×, using computer-aided design software (CAD) and generating printed models of bacteria on mass-market 3D printers. Sixteen models are presented, including rod-shaped, spiral, flask-like, vibroid, …

Comparisons Of Oral, Intestinal, And Pancreatic Bacterial Microbiomes In Patients With Pancreatic Cancer And Other Gastrointestinal Diseases, Mei Chung, Naisi Zhao, Richard Meier, Devin C. Koestler, Guojun Wu, Erika De Castillo, Bruce J. Paster, Kevin Charpentier, Jacques Izard, Karl T. Kelsey, Dominique S. Michaud

Department of Food Science and Technology: Faculty Publications

Background: Oral microbiota is believed to play important roles in systemic diseases, including cancer. Methods: We collected oral samples (tongue, buccal, supragingival, and saliva) and pancreatic tissue or intestinal samples from 52 subjects, and characterized 16S rRNA genes using high-throughput DNA sequencing.

Results: Bray–Curtis plot showed clear separations between bacterial communities in the oral cavity and those in intestinal and pancreatic tissue samples. PERMANOVA tests indicated that bacterial communities from buccal samples were similar to supragingival and saliva samples, and pancreatic duct samples were similar to pancreatic tumor samples, but all other samples were significantly different from each …

Investigating Microbial And Host Factors That Modulate Severity Of Clostridioides Difficile Associated Disease, Armando Lerma

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Clostridioides difficile is recognized as one of the most important pathogens in hospital and community healthcare settings. The clinical outcome of infection of toxigenic C. difficile infection (CDI) ranges from asymptomatic colonization to fulminant pseudomembranous colitis and death. In recent studies, it has been suggested that a high proportion of nosocomial CDI cases are transmitted from asymptomatic carriers which might be acting as infection reservoirs. Understanding what causes the different responses to infection could lead to the development of novel prevention and treatment strategies. Although several explanations have been proposed to explain variations in susceptibility, understanding of the exact mechanisms …

Investigation Of Rapid Diagnostic Tests For Characterization Of Mycobacterium Avium Complex (Mac) From Various Isolates And Identification Of Virulence Factors Of Porcine Reproductive And Respiratory Syndrome Virus (Prrsv) In Vitro, Claudia Antonika

UCARE: Research Products

Chapter 1

Mycobacterium avium complex (MAC) has become one of the major problems in public health and livestock. Members of MAC, such as M. avium subsp paratuberculosis (MAP) and M. avium subsp hominissuis (MAH), are responsible for many opportunistic infections and the loss of livestock. MAP is economically significant to the beef and dairy industries because it is the etiologic agent of Johnes’s disease, a chronic and fatal enteritis in ruminants. Tracing the infection sources of MAC could be difficult since it infects many types of hosts in the natural environment. Furthermore, there is less information known about MAP pathogenicity …

Mucosa-Associated Microbiota In Barrett’S Esophagus, Dysplasia, And Esophageal Adenocarcinoma Differ Similarly Compared With Healthy Controls, Shajan Peter, Amanda Pendergraft,, William Vanderpol, Mel Wilcox, Kondal R. Kyanam Kabir Baig, Casey Morrow, Jacques Izard, Peter J. Mannon

Department of Food Science and Technology: Faculty Publications

Introduction: Alterations in the composition of the human gut microbiome and its metabolites have been linked to gut epithelial neoplasia. We hypothesized that differences in mucosa-adherent Barrett’s microbiota could link to risk factors, providing risk of progression to neoplasia.

Methods: Paired biopsies from both diseased and nonaffected esophagus (as well as gastric cardia and gastric juice for comparison) from patients with intestinal metaplasia (n = 10), low grade dysplasia (n = 10), high grade dysplasia (n = 10), esophageal adenocarcinoma (n = 12), and controls (n = 10) were processed for mucosa-associated bacteria …

Triatomines: Trypanosomatids, Bacteria, And Viruses Potential Vectors?, Caroline Barreto Viera, Yanna Reis Praça, Kaio Luis Da Silva Bentes, Paula Beatriz Santiago, Sofia Marcelino Martins Silva, Gabriel Dos Santos Silva, Flávia Nader Motta, Izabela Marques Dourado Bastos, Jaime Martins De Santana, Carla Nunes De Araújo

Harold W. Manter Laboratory of Parasitology: Library Materials

Triatominae bugs are the vectors of Chagas disease, a major concern to public health especially in Latin America, where vector-borne Chagas disease has undergone resurgence due mainly to diminished triatomine control in many endemic municipalities. Although the majority of Triatominae species occurs in the Americas, species belonging to the genus Linshcosteus occur in India, and species belonging to the Triatoma rubrofasciata complex have been also identified in Africa, the Middle East, South-East Asia, and in the Western Pacific. Not all of Triatominae species have been found to be infected with Trypanosoma cruzi, but the possibility of establishing vector transmission …

Triatomines: Trypanosomatids, Bacteria, And Viruses Potential Vectors? [Review], Caroline Barreto Vieira, Yanna Reis Praça, Kaio Luís Da Silva Bentes, Paula Beatriz Santiago, Sofia Marcelino Martins Silva, Gabriel Dos Santos Silva, Flávia Nader Motta, Izabela Marques Dorado Bastos, Jaime Martins De Santana, Carla Nunes De Araújo

Harold W. Manter Laboratory of Parasitology: Library Materials

Triatominae bugs are the vectors of Chagas disease, a major concern to public health especially in Latin America, where vector-borne Chagas disease has undergone resurgence due mainly to diminished triatomine control in many endemic municipalities. Although the majority of Triatominae species occurs in the Americas, species belonging to the genus Linshcosteus occur in India, and species belonging to the Triatoma rubrofasciata complex have been also identified in Africa, the Middle East, South-East Asia, and in the Western Pacific. Not all of Triatominae species have been found to be infected with Trypanosoma cruzi, but the possibility of establishing vector transmission …

In Vitro Assay Development As An Alternative To The Use Of Laboratory Animals For Measuring Clostridium Perfingens Type C Toxoid, Lauren M. Wilmes

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

Clostridium perfringens type C produces beta toxin, which is a primary virulence determinate that can cause necrotic enteritis in neonatal animals. Vaccines directed against C. perfringens toxins have shown to be efficacious in preventing disease. However, the production of a commercial vaccine requires not only an efficacious antigen, but also testing methods for quantifying antigens and potency on final product. This research was undertaken to fulfill a need for the reduction in small animal usage to produce and deliver vaccines. The current testing methods are performed in vivo according to the Code of Federal Regulations number 9 (9CFR) United …

Rapid Identification And Typing Of Mycobacterium Avium Complex Using Matrix Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry (Maldi-Tof) Library And Biomarker Based Approaches, Claudia Antonika, John Dustin Loy, Raul Barletta, Michael Collins

UCARE: Research Products

Bacteria associated with the Mycobacterium avium complex (MAC) cause significant problems in animal agriculture and cause large economic losses and morbidity of livestock. Two clinically important subspecies of M. avium are M.avium ssp paratuberculosis (MAP) and M. avium ssp hominissuis (MAH). MAP is the etiologic agent of Johne’s disease, a chronic and fatal enteritis in ruminants, that has been linked to Crohn’s disease in humans.1 MAH has zoonotic potential as it is one of the leading causes of secondary infections in AIDS patients. Identification of M. avium in clinical samples is challenging as they have overlapping host ranges and clinical …

Amp Expression In Energetic Hybrid D. Melanogaster Infected With P. Rettgeri, Cassandra K. Treu, Justin Buchanan, Kristi Montooth

UCARE: Research Products

The purpose of this experiment was to investigate immune function and energy metabolism, particularly the levels of antimicrobial peptides produced in Drosophila energetically compromised genotypes. This will provide the ability to investigate energetics of immunity without changing diet. Flies were infected with the bacteria P. rettgeri and the resulting immune response was investigated. Females did not mount as effective an immune response as males. All flies exhibited decreased survivorship from infection. Control flies survived at higher levels and showed no mitochondrial:nuclear interaction.

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 …

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 …

Concomitant Uptake Of Antimicrobials And Salmonella In Soil And Into Lettuce Following Wastewater Irrigation, J. Brett Sallach, Yuping Zhang, Laurie Hodges, Daniel D. Snow, Xu Li, Shannon L. Bartelt-Hunt

Department of Civil and Environmental Engineering: Faculty Publications

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and …

Metagenomics For Bacteriology, Erika Del Castillo, Jacques Izard

Department of Food Science and Technology: Faculty Publications

The study of bacteria, or bacteriology, has gone through transformative waves since its inception in the 1600s. It all started by the visualization of bacteria using light microscopy by Antonie van Leeuwenhoek, when he first described “animalcules.” Direct cellular observation then evolved into utilizing different wavelengths on novel platforms such as electron, fluorescence, and even near-infrared microscopy. Understanding the link between microbes and disease (pathogenicity) began with the ability to isolate and cultivate organisms through aseptic methodologies starting in the 1700s. These techniques became more prevalent in the following centuries with the work of famous scientists such as Louis Pasteur …

A Prospective Study Of Periodontal Disease And Risk Of Gastric And Duodenal Ulcer In Male Health Professionals, Matthew R. Boylan, Hamed Khalili, Edward S. Huang, Dominique S. Michaud, Jacques Izard, Kaumudi J. Joshipura, Andrew T. Chan

Department of Food Science and Technology: Faculty Publications

Periodontal disease is characterized by microbial shifts within the oral cavity and chronic inflammation of the gingival tissue, and can lead to tooth loss. Several studies support an association between periodontal disease and risk of chronic systemic conditions, including vascular disease, chronic obstructive pulmonary disease, diabetes mellitus, and cancer, including gastric adenocarcinoma. These associations may be mediated by systemic inflammation, the immune response to periodontal infection, or direct invasion by pathogens. Previous studies of periodontal disease and risk of peptic ulcer have been limited by cross-sectional design, diagnoses that were not confirmed by medical record review, and a lack of …

Neisseria Oralis Sp. Nov., Isolated From Healthy Gingival Plaque And Clinical Samples, William J. Wolfgang, Teresa V. Passaretti, Reashma Jose, Jocelyn Cole, An Coorevits, Andrea N. Carpenter, Sherly Jose, Anita Van Landschoot, Jacques Izard, Donna J. Kohlerschmidt, Peter Vandamme, Floyd E. Dewhirst, Mark A. Fisher, Kimberlee A. Musser

Department of Food Science and Technology: Faculty Publications

A polyphasic analysis was undertaken of seven independent isolates of gram-negative cocci collected from pathological clinical samples from New York, Louisiana, Florida, and Illinois and healthy subgingival plaque from a patient in Virginia, USA. The 16S rRNA gene sequence similarity among these isolates was 99.7–100 %, and the closest species with a validly published name was Neisseria lactamica (96.9 % similarity to the type strain). DNA–DNA hybridization confirmed that these isolates are of the same species and are distinct from their nearest phylogenetic neighbor, N. lactamica. Phylogenetic analysis of 16S and 23S rRNA gene sequences indicated that the …

Seroprevalence Of Brucellosis In Livestock Within Three Endemic Regions Of The Country Of Georgia, Eliso Mamisashvili, Ian T. Kracalik, Tinatin Onashvili, Lela Kerdzevadze, Ketevan Goginashvili, Tamar Tigilauri, Marina Donduashvili, Marina Nikolaishvili, Irma Beradze, Marina Zakareishvili, Maka Kokhreidze, Makvala Gelashvili, Nino Vepkhvadze, S. Elizabeth Rácz, Philip H. Elzer, Mikeljon P. Nikolich, Jason K. Blackburn

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Brucellosis is the one of most common livestock zoonoses in Georgia, resulting in significant economic losses. Livestock were sampled in three regions of Georgia (Kakheti, Kvemo Kartli, Imereti). Districts that historically reported high numbers of brucellosis related morbidity were selected for serological, bacteriological and molecular surveys. Surveying efforts yielded samples from 10,819 large and small ruminants. In total, 735 serological tests were positive on Rose Bengal and 33 bacterial isolates were recovered and identified as Brucella melitensis or Brucella abortus by microbiology and AMOS-PCR. A Bayesian framework was implemented to estimate the true prevalence of the disease given an imperfect …

The Evolution Of Host Specificity In The Vertebrate Gut Symbiont Lactobacillus Reuteri, Steven Frese

Department of Food Science and Technology: Dissertations, Theses, and Student Research

The vertebrate gut is home to one of the densest populations of life on Earth. This microbial community has a profound effect on host health, nutrition, development, behavior, and evolution. However, very little is known about how these microbes have evolved with their vertebrate hosts, how and whether they select hosts or how they remain associated with their hosts. Recent work identified Lactobacillus reuteri as an organism that is composed of host-specific sub-populations, each population associated with a different host animal. Representatives from each host-associated population were tested for their ability to colonize gnotobiotic mice, which only rodent strains could …

Composition Of The Adult Digestive Tract Bacterial Microbiome Based On Seven Mouth Surfaces, Tonsils, Throat And Stool Samples, Nicola Segata, Susan Kinder Haake, Peter Mannon, Katherine P. Lemon, Levi Waldron, Dirk Gevers, Curtis Huttenhower, Jacques Izard

Department of Food Science and Technology: Faculty Publications

Background: To understand the relationship between our bacterial microbiome and health, it is essential to define the microbiome in the absence of disease. The digestive tract includes diverse habitats and hosts the human body’s greatest bacterial density. We describe the bacterial community composition of ten digestive tract sites from more than 200 normal adults enrolled in the Human Microbiome Project, and metagenomically determined metabolic potentials of four representative sites.

Results: The microbiota of these diverse habitats formed four groups based on similar community compositions: buccal mucosa, keratinized gingiva, hard palate; saliva, tongue, tonsils, throat; sub- and supra-gingival plaques; …

Efficient And Robust Rna-Seq Process For Cultured Bacteria And Complex Community Transcriptomes, Georgia Giannoukos, Dawn M. Ciulla, Katherine Huang, Brian J. Haas, Jacques Izard, Joshua Z. Levin, Jonathan Livny, Ashlee M. Earl, Dirk Gevers, Doyle V. Ward, Chad Nusbaum, Bruce W. Birren, Andreas Gnirke

Department of Food Science and Technology: Faculty Publications

We have developed a process for transcriptome analysis of bacterial communities that accommodates both intact and fragmented starting RNA and combines efficient rRNA removal with strand-specific RNA-seq. We applied this approach to an RNA mixture derived from three diverse cultured bacterial species and to RNA isolated from clinical stool samples. The resulting expression profiles were highly reproducible, enriched up to 40-fold for non-rRNA transcripts, and correlated well with profiles representing undepleted total RNA.

Bacterial Community Structure Of Contrasting Soils Underlying Bornean Rain Forests: Inferences From Microarray And Next-Generation Sequencing Methods, Sabrina E. Russo, Ryan Legge, Karrie A. Weber, Eoin L. Brodie, Katherine C. Goldfarb, Andrew K. Benson, Sylvester Tan

School of Biological Sciences: Faculty Publications

Soil microbial diversity is vast, and we lack even basic understanding of how this diversity is distributed ecologically. Using pyrosequencing and microarray methods, we quantified the structure of bacterial communities in two contrasting soils underlying Bornean rain forest (clay and sandy loam) that differ markedly in soil properties, aboveground tree flora, and leaf litter decomposition rates. We found significant soil-related taxonomic and phylogenetic differences between communities that, due to their proximity, are independent of climate. Bacterial communities showed distinct compositional and taxon-abundance distributions that were significantly correlated with the structure of the overlying tree community. Richness of bacteria was greater …

Staphylococcus Aureus Virulence Factors Synthesis Is Controlled By Central Metabolism, Yefei Zhu

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

Staphylococcus aureus is a versatile pathogen that can survive in diverse host environments. This versatility depends on its ability to sense nutrients and respond by modulating gene expression, including the synthesis of virulence determinants. In addition to its ability to synthesize virulence factors, the capacity of S. aureus to form biofilms is an important mediator of virulence in certain infections. Biofilms are a complex aggregation of bacteria commonly encapsulated by an adhesive exopolysaccharide matrix (polysaccharide intercellular adhesin; PIA). To study S. aureus biofilm formation, we assessed the metabolic requirements of S. aureus growing in a biofilm and …

The Human Oral Microbiome, Floyd E. Dewhirst, Tuste Chen, Jacques Izard, Bruce J. Paster, Anne C. R. Tanner, Wen-Han Yu, Abirami Lakshmanan, William G. Wade

Department of Food Science and Technology: Faculty Publications

The human oral cavity contains a number of different habitats, including the teeth, gingival sulcus, tongue, cheeks, hard and soft palates, and tonsils, which are colonized by bacteria. The oral microbiome comprises over 600 prevalent taxa at the species level, with distinct subsets predominating at different habitats. The oral microbiome has been extensively characterized by cultivation and culture-independent molecular methods such as 16S rRNA cloning. Unfortunately, the vast majority of unnamed oral taxa are referenced by clone numbers or 16S rRNA GenBank accession numbers, often without taxonomic anchors. The first aim of this research was to collect 16S rRNA gene …

Growth Of Lactic Acid Bacteria: Influence Of Protocooperation, Bacteriophage Infection, And Prebiotic Carbohydrates, Caitlin D. Goin

School of Biological Sciences: Dissertations, Theses, and Student Research

Lactic acid bacteria are a vital part of the fermented food industry and are the subject of much interest and research. Industry is especially interested in using modern molecular approaches to maintain and improve selected strains; several industrial uses could be improved by closer investigation, namely the protocooperation of S. thermophilus and L. bulgaricus, the role of CRISPRs in phage resistance, and the utilization of prebiotic carbohydrates. Questions such as what genes and pathways are shared during milk fermentation between S. thermophilus and L. bulgaricus, when and what genes are active during bacteriophage infection, and how and where …

Killing Of Treponema Denticola By Mouse Peritoneal Macrophages, P. Gaibani, C. Vocale, S. Ambretti, F. Cavrini, Jacques Izard, L. Miragliotta, M. T. Pellegrino, V. Sambri

Department of Food Science and Technology: Faculty Publications

Treponema denticola has been identified as an important cause of periodontal disease and hypothesized to be involved in extra-oral infections. The objective of this study was to investigate the role of T. denticola cell length and motility during mouse peritoneal macrophages in vitro uptake. Macrophages, incubated under aerobic and anaerobic conditions, produced a similar amount of TNF-α when stimulated with Escherichia coli LPS. The uptake of FlgE- and CfpA-deficient mutants of T. denticola was significantly increased compared with the wild-type strain, due to cell size or lack of motility. Opsonization with specific antibodies considerably improved the treponemes’ uptake. …

Native Cellular Architecture Of Treponema Denticola Revealed By Cryo-Electron Tomography, Jacques Izard, Chyong-Ere Hsieh, Ronald J. Limberger, Carmen A. Mannella, Michael Marko

Department of Food Science and Technology: Faculty Publications

Using cryo-electron tomography, we are developing a refined description of native cellular structures in the pathogenic spirochete Treponema denticola. Tightly organized bundles of periplasmic flagella were readily observed in intact plunge-frozen cells. The periplasmic space was measured in both wild-type and aflagellate strains, and found to widen by less than the diameter of flagella when the latter are present. This suggests that a structural change occurs in the peptidoglycan layer to accommodate the presence of the flagella. In dividing cells, the flagellar filaments were found to bridge the cytoplasmic cylinder constriction site. Cytoplasmic filaments, adjacent to the inner membrane, …

Pyramidobacter Piscolens Gen. Nov., Sp. Nov., A Member Of The Phylum ‘Synergistetes’ Isolated From The Human Oral Cavity, Julia Downes, Sonia R. Vartoukian, Floyd E. Dewhirst, Jacques Izard, Tsute Chen, Wen-Han Yu, Iain C. Sutcliffe, William G. Wade

Department of Food Science and Technology: Faculty Publications

Four strains of anaerobic, gram-negative bacilli isolated from the human oral cavity were subjected to a comprehensive range of phenotypic and genotypic tests and were found to comprise a homogeneous group distinct from any species with validly published names. 16S rRNA and 23S rRNA gene sequence analyses and DNA–DNA reassociation data revealed that the strains constituted a novel group within the phylum ‘Synergistetes’ and were most closely related to Jonquetella anthropi. Two libraries of randomly cloned DNA were prepared from strain W5455T and were sequenced to provide a genome survey as a resource for metagenomic studies. A new genus …

Cryo-Electron Tomography Elucidates The Molecular Architecture Of Treponema Pallidum, The Syphilis Spirochete, Jacques Izard, Christian Renken, Chyong-Ere Hsieh, Daniel C. Desrosiers, Star Dunham-Ems, Carson La Vake, Linda L. Gebhardt, Ronald J. Limberger, David L. Cox, Michael Marko, Justin D. Radolf

Department of Food Science and Technology: Faculty Publications

Cryo-electron tomography (CET) was used to examine the native cellular organization of Treponema pallidum, the syphilis spirochete. T. pallidum cells appeared to form flat waves, did not contain an outer coat and, except for bulges over the basal bodies and widening in the vicinity of flagellar filaments, displayed a uniform periplasmic space. Although the outer membrane (OM) generally was smooth in contour, OM extrusions and blebs frequently were observed, highlighting the structure’s fluidity and lack of attachment to underlying periplasmic constituents. Cytoplasmic filaments converged from their attachment points opposite the basal bodies to form arrays that ran roughly …

Genetic Microheterogeneity And Phenotypic Variation Of Helicobacter Pylori Arginase In Clinical Isolates, Justin Hovey, Emily Watson, Melanie Langford, Ellen Hildebrandt, Sangeetha Bathala, Jeffrey Bolland, Domenico Spadafora, George Mendz, David Mcgee

School of Biological Sciences: Faculty Publications

Background: Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid.

Results: The degree of variation in arginase was explored at the DNA sequence, enzyme activity and protein expression levels. To this end, arginase activity was measured from 73 minimally-passaged clinical isolates and six laboratory-adapted strains …