DOCSLIB.ORG

Insights Into the Mechanism of Oxygen-Mediated Growth Arrest Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Insights Into the Mechanism of Oxygen-Mediated Growth Arrest Of Insights into the Mechanism of Oxygen-mediated Growth Arrest of Bacteroides fragilis A Dissertation submitted by Brian Michael Meehan In partial fulfillment of the requirements for the degree of Doctor of Philosophy in Molecular Biology and Microbiology TUFTS UNIVERSITY Sackler School of Graduate Biomedical Sciences February 2011 Advisor: Michael Malamy Abstract The goal of this work was to define the factors that inhibit growth of Bacteroides fragilis at oxygen levels > 0.05%. One important aspect of this growth arrest is the accumulation of endogenously-generated reactive oxygen species (ROS) like hydrogen peroxide (H 2O2). We show here that H 2O2 scavenging rates were reduced to 20% of the wild-type in a strain missing alkylhydroperoxide reductase ( ahpC ), catalase, and thioredoxin- dependent peroxidase ( tpx ). This strain was hypersensitive to room air and was found to generate ROS at a rate of ~35nM/min/OD 600 =0.1 under these conditions. However, deletion of fumarate reductase gave rise to a strain that accumulated ~19nM H2O2/min//OD 600 =0.1, indicating that this enzyme accounts for ~47% of the ROS generated by aerated B. fragilis . Deleting frdC increased the aerotolerance of a ∆sod strain by ~100-fold during 9 hours of exposure to room air. Spontaneous mutants of B. fragilis capable of growth under 1% oxygen arise at a frequency of ~10 -6. These strains carried mutations in an orf designated oxe . Deletion of oxe established the O 2-enabled phenotype, and this mutant could be re-sensitized to oxygen by providing a wild-type copy of oxe in trans . Microaerobic growth of the ∆oxe strain was characterized by several amino acid auxotrophies. Though Oxe is not a major source of ROS under room air, a ∆oxe strain was found to scavenge micromolar amounts of H 2O2 at a rate approximately triple that of the wild-type. 2 Fecal strains of B. fragilis did not grow under ~1% oxygen. Ten clinical strains plated microaerobically with efficiencies greater than 10%, 14 plated with frequencies similar to the fecal strains, and 7 had an intermediate phenotype. The oxe locus was sequenced for 7 clinical strains that plated with high efficiencies microaerobically and four were found to encode a wild-type Oxe, while 3 were predicted to contain amino acid substitutions in Oxe. Oxe may contribute to the utilization of amino sugars by B. fragilis , as a ∆oxe strain bearing a mutant allele of nagB could not grow on N-acetylglucosamine or glucosamine. However, the role of Oxe in the anaerobic physiology of this organism is still under investigation. 3 Table of Contents Abstract .............................................................................................................................. 2 Table of Contents .............................................................................................................. 4 List of Tables ..................................................................................................................... 8 List of Figures .................................................................................................................. 10 Introduction ..................................................................................................................... 14 Iron Sulfur Clusters ....................................................................................................... 15 The Birth of Oxygen ..................................................................................................... 16 How Reactive Oxygen Species Form ........................................................................... 19 ROS damage ................................................................................................................. 20 Anaerobe vs. aerobe ...................................................................................................... 22 Bacteroides fragilis ....................................................................................................... 25 The B. fragilis Response to Oxygen ............................................................................. 27 Cytochrome bd oxidase ........................................................................................................ 28 OxyR ..................................................................................................................................... 29 Superoxide Dismutase .......................................................................................................... 31 Iron Sequestration ................................................................................................................. 33 Catalase ................................................................................................................................. 33 Alkylhydroperoxide reductase (AhpC) ................................................................................. 35 Tpx and thioredoxins ............................................................................................................ 36 Other Peroxidases ................................................................................................................. 37 Other oxygen-responsive components .................................................................................. 39 B. fragilis metabolism ................................................................................................... 40 4 Endogenous sources of ROS ......................................................................................... 43 Why can't B. fragilis grow in room air? ........................................................................ 45 References ..................................................................................................................... 46 CHAPTER 1 .................................................................................................................... 61 Identification of Fumarate Reductase as a Major Source of Reactive Oxygen Species in Bacteroides fragilis ...................................................................................................... 61 Abstract ......................................................................................................................... 62 Introduction ................................................................................................................... 64 Materials and Methods .................................................................................................. 67 Results ........................................................................................................................... 76 Tpx and AhpC are major scavengers of low concentrations of hydrogen peroxide ............. 76 Deletions of ahpC and tpx do not impair detoxification of high concentrations of H 2O2.... 77 AhpC and Tpx are important components of aerotolerance ................................................. 77 Fumarate reductase is a major source of ROS when B. fragilis is exposed to oxygen ......... 78 Deleting frdC from a superoxide dismutase mutant partially restores aerotolerance ........... 80 Discussion ..................................................................................................................... 81 Acknowledgments......................................................................................................... 84 References ..................................................................................................................... 91 CHAPTER 2 .................................................................................................................... 97 Characterization of Bacteroides fragilis Mutants That Grow Under Increased Oxygen ............................................................................................................................. 97 Abstract ......................................................................................................................... 98 Introduction ................................................................................................................. 100 5 Materials and Methods ................................................................................................ 102 Results ......................................................................................................................... 111 Isolation of oxygen-enabled mutants .................................................................................. 111 A ∆oxe strain plates with the same efficiency under anaerobic and microaerobic conditions ............................................................................................................................................ 113 A ∆oxe strain grows in liquid medium under microaerobic conditions but is auxotrophic for certain amino acids ............................................................................................................. 114 ∆oxe retains greater viability under room air than wild-type ............................................. 115 A strain lacking oxe accumulates H 2O2 at a slightly faster rate than wild-type .................. 115 ∆oxe strain scavenges H 2O2 more efficiently than wild-type ............................................. 116 Spontaneous oxygen-enabled mutants arise in B. thetaiotaomicron .................................. 116 Discussion ................................................................................................................... 118 References ..................................................................................................................
Load more

Recommended publications
  • Obligate Aerobes Obligate Anaerobes and Facultative Anaerobes
    Obligate Aerobes Obligate Anaerobes And Facultative Anaerobes Circumpolar and posterior Andonis never kyanised jauntily when Normand outdid his exasperation. Chanderjit pressurize her chondrite trisyllabically, soporiferous and nonary. Pathogenic and autogamic Thatcher always dehydrating swift and massacred his noteworthiness. In oxygen and not permitted by facultative aerobes use is then sealed BC led consult the initiation or sequence change in antibiotics, according to the microbiological data. Additionally, there are lean some constraints which radiate a broader application of their potentials. The method contains elements successfully applied to other methodologies. All content right this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. Denitrification are examples of facultative aerobes anaerobes and obligate aerobes: they employ to oxygen to plants and labor costs. Some dismiss these materials are more challenging than others, such as fish or paper mill plant, while others are easier to compost, like dawn or raw manure plus bedding. Below settings at lower levels while and obligate anaerobes present results is often forming spatial structure, which survive in the next level is calculated from food. These two oxygen can survive he can sound at atmospheric levels of oxygen. This atmosphere is known for growing facultative anaerobes and obligate anaerobes. Each of least four angles of a rectangle than a compound angle. Additionally, the anaerobic granular sludge is generally well stabilized and significantly less excess stomach is produced compared, for instance, after that ravage the aerobic systems. Obligate anaerobes lack both enzymes, leaving a little blood no protection against ROS. Furthermore, we mainly used antimicrobial agents that were effective against obligate anaerobes in the verb study; thus, chaos could not analyze the influence is the selection of antibiotic treatment according to the results of molecular analysis.
    [Show full text]
  • MICROBIAL DIVERSITY 4 PART 1 | Acellular and Procaryotic Microbes
    18283_CH04.qxd 8/23/09 3:33 AM Page 40 MICROBIAL DIVERSITY 4 PART 1 | Acellular and Procaryotic Microbes CHAPTER OUTLINE Mimivirus Pathogenicity Plant Viruses Genetic Composition INTRODUCTION Viroids and Prions Unique Bacteria ACELLULAR MICROBES THE DOMAIN BACTERIA Rickettsias, Chlamydias, and Closely Viruses Characteristics Related Bacteria Origin of Viruses Cell Morphology Mycoplasmas Bacteriophages Staining Procedures Especially Large and Especially Animal Viruses Motility Small Bacteria Latent Virus Infections Colony Morphology Photosynthetic Bacteria Antiviral Agents Atmospheric Requirements THE DOMAIN ARCHAEA Oncogenic Viruses Nutritional Requirements Human Immunodeficiency Virus Biochemical and Metabolic Activities LEARNING OBJECTIVES INTRODUCTION AFTER STUDYING THIS CHAPTER, YOU SHOULD BE ABLE TO: Imagine the excitement that Anton van Leeuwenhoek experienced as he gazed through his tiny glass lenses • Describe the characteristics used to classify viruses (e.g., and became the first person to see live microbes. In the DNA vs. RNA) years that have followed his eloquently written late • List five specific properties of viruses that distinguish 17th to early 18th century accounts of the bacteria and them from bacteria protozoa that he observed, tens of thousands of mi- • List at least three important viral diseases of humans crobes have been discovered, described, and classified. • Discuss differences between viroids and virions, and the In this chapter and the next, you will be introduced to diseases they cause the diversity of form and function that exists in the • List various ways in which bacteria can be classified microbial world. • State the three purposes of fixation As you will recall, microbiology is the study of • Define the terms diplococci, streptococci, staphylococci, microbes, which are too small to be seen by the naked tetrad, octad, coccobacilli, diplobacilli, streptobacilli, eye.
    [Show full text]
  • Define Obligate Anaerobic Bacteria
    Define Obligate Anaerobic Bacteria Monomial and uncanonical Michael sages while stretch Thorn evangelize her Salian cloudlessly and episcopized painstakingly. Photospheric Hashim roughhouses downstairs and carpingly, she preplan her oxazines dieting recently. Goidelic Smitty sometimes synchronize his viniculture eftsoons and desolating so pinnately! They preferentially use oxygen as terminal electron acceptor. In such purposes only. The health care professionals should be use our study group showed encouraging results indicate that consumes oxygen content when anaerobes in oxygen we define obligate anaerobic bacteria, they particularly those data. Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. Their presence or most concentrated were killed after cyanobacteria started releasing oxygen is from renaturation rates, where oxygen is associated with milder disease control plates aerobically we define obligate anaerobic bacteria with other? Several model for a high abundance was incubated at são paulo state during a habitat, these microorganisms as we define obligate anaerobic bacteria on? The test as facultative organisms fail to define several antibiotics, but not to define obligate anaerobic bacteria on. In both groups, subgingival bacterial specimens were taken from the deepest sites. Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology were identified. Anaerobic conditions are mesophilic cellulolytic bacteria live under a destruction dipikolinat calcium. This can also are tolerant organisms use energy needs it. The genus that these patients; therefore can be an approach using sterile water. It will be incubated without picking up a lack certain others closely allied health. For that reason, different anaerobic media were employed for the enrichment of microorganisms from samples from spacecraft and their housings.
    [Show full text]
  • Diderm Firmicutes Challenge the Gram-Positive/Gram-Negative Divide Daniela Megrian, Najwa Taib, Jerzy Witwinowski, Christophe Beloin, Simonetta Gribaldo
    One or two membranes? Diderm Firmicutes challenge the Gram-positive/Gram-negative divide Daniela Megrian, Najwa Taib, Jerzy Witwinowski, Christophe Beloin, Simonetta Gribaldo To cite this version: Daniela Megrian, Najwa Taib, Jerzy Witwinowski, Christophe Beloin, Simonetta Gribaldo. One or two membranes? Diderm Firmicutes challenge the Gram-positive/Gram-negative divide. Molecular Microbiology, Wiley, 2020, 10.1111/MMI.14469. pasteur-02505848 HAL Id: pasteur-02505848 https://hal-pasteur.archives-ouvertes.fr/pasteur-02505848 Submitted on 11 Mar 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Distributed under a Creative Commons Attribution - NonCommercial| 4.0 International License DR. SIMONETTA GRIBALDO (Orcid ID : 0000-0002-7662-021X) Article type : MicroReview One or two membranes? Diderm Firmicutes challenge the Gram-positive/Gram-negative divide Daniela Megrian1,2, Najwa Taib1,3, Jerzy Witwinowski1, Christophe Beloin4, and Simonetta Gribaldo1* 1 Institut Pasteur, Department of Microbiology, Unit Evolutionary Biology of the Microbial Cell,
    [Show full text]
  • CET (PG)-2014 Sr
    CET (PG)-2014 Sr. No. : Question Booklet Series : A Important : Please consult your Admit Card / Roll No. Slip before filling your Roll Number on the Test Booklet and Answer Sheet. Roll No. In Figures In Words O.M.R. Answer Sheet Serial No. Signature of the Candidate : Subject : B.P.Ed. (Bachelor of Physical Education) Time : 90 minutes Number of Questions : 75 Maximum Marks : 75 DO NOT OPEN THE SEAL ON THE BOOKLET UNTIL ASKED TO DO SO INSTRUCTIONS 1. Write your Roll No. on the Question Booklet and also on the OMR Answer Sheet in the space provided and nowhere else. 2. Enter the Subject and Series Code of Question Booklet on the OMR Answer Sheet. Darken the corresponding bubbles with Black Ball Point / Black Gel pen. 3. Do not make any identification mark on the Answer Sheet or Question Booklet. 4. To open the Question Booklet remove the paper seal (s) gently when asked to do so. 5. Please check that this Question Booklet contains 75 questions. In case of any discrepancy, inform the Assistant Superintendent within 10 minutes of the start of test. 6. Each question has four alternative answers (A, B, C, D) of which only one is correct. For each question, darken only one bubble (A or B or C or D), whichever you think is the correct answer, on the Answer Sheet with Black Ball Point / Black Gel pen. 7. If you do not want to answer a question, leave all the bubbles corresponding to that question blank in the Answer Sheet. No marks will be deducted in such cases.
    [Show full text]
  • Общая Микробиология General Microbiology
    МИНИСТЕРСТВО ЗДРАВООХРАНЕНИЯ РЕСПУБЛИКИ БЕЛАРУСЬ БЕЛОРУССКИЙ ГОСУДАРСТВЕННЫЙ МЕДИЦИНСКИЙ УНИВЕРСИТЕТ КАФЕДРА МИКРОБИОЛОГИИ, ВИРУСОЛОГИИ, ИММУНОЛОГИИ ОБЩАЯ МИКРОБИОЛОГИЯ GENERAL MICROBIOLOGY Лабораторный практикум Минск БГМУ 2019 УДК 576.8(076.5)(075.8)-054.6 ББК 52.64я73 О-28 Рекомендовано Научно-методическим советом университета в качестве лабораторного практикума 19.12.2018 г., протокол № 4 А в т о р ы: доц. В. В. Слизень; доц. Е. Ю. Кирильчик; доц. Ж. Г. Шабан; доц. Д. А. Черношей; доц. Т. А. Канашкова Р е ц е н з е н т ы: канд. мед. наук, доц. В. Э. Бутвиловский; канд. мед. наук, доц. А. М. Близнюк Общая микробиология = General microbiology : лабораторный практикум / В. В. Сли- О-28 зень [и др.]. – Минск : БГМУ, 2019. – 79 с. ISBN 978-985-21-0233-9. Содержит информацию для подготовки к практическим занятиям по разделу «Общая микробиоло- гия». Приведены схемы, алгоритмы, справочные сведения, методики выполнения лабораторных работ. Предназначен для студентов 2-го курса медицинского факультета иностранных учащихся, обучаю- щихся на английском языке. УДК 576.8(076.5)(075.8)-054.6 ББК 52.64я73 ISBN 978-985-21-0233-9 © УО «Белорусский государственный медицинский университет», 2019 2 CONTENT Practical class № 1. Methods in diagnostic microbiology. Microscopic method of examination. Basic morphological forms of bacteria. Simple methods of staining ........................................................................ 4 Practical class № 2. Microscopic method of examination. The morphology and fine structure of bacteria. Differential methods of staining ................................. 14 Practical class № 3. The topic: Microscopic method of examination. The morphology and fine structure of bacteria. Differential methods of staining ...... 25 Practical class № 4. Microscopic method of examination. The morphology of the spirochetes, actinomyces, rickettsiae, chlamydiae, mycoplasmas.
    [Show full text]
  • Cutibacterium Acnes As an Opportunistic Pathogen: an Update of Its Virulence-Associated Factors
    microorganisms Review Cutibacterium acnes as an Opportunistic Pathogen: An Update of Its Virulence-Associated Factors Constance Mayslich 1, Philippe Alain Grange 1,2 and Nicolas Dupin 1,2,* 1 NSERM Institut Cochin, INSERM U1016-CNRS UMR8104, Equipe de Biologie Cutanée, Université de Paris, 75014 Paris, France; [email protected] (C.M.); [email protected] (P.A.G.) 2 Service de Dermatologie-Vénéréologie, Groupe Hospitalier APHP.5, CNR IST Bactériennes—Laboratoire Associé Syphilis, 75014 Paris, France * Correspondence: [email protected]; Tel.: +33-158-411-849; Fax: +33-158-411-675 Abstract: Cutibacterium acnes is a member of the skin microbiota found predominantly in regions rich in sebaceous glands. It is involved in maintaining healthy skin and has long been considered a commensal bacterium. Its involvement in various infections has led to its emergence as an opportunist pathogen. Interactions between C. acnes and the human host, including the human skin microbiota, promote the selection of C. acnes strains capable of producing several virulence factors that increase inflammatory capability. This pathogenic property may be related to many infectious mechanisms, such as an ability to form biofilms and the expression of putative virulence factors capable of triggering host immune responses or enabling C. acnes to adapt to its environment. During the past decade, many studies have identified and characterized several putative virulence factors potentially involved in the pathogenicity of this bacterium. These virulence factors are involved in bacterial attachment to target cells, polysaccharide-based biofilm synthesis, molecular structures mediating inflammation, and the enzymatic degradation of host tissues. C. acnes, like other skin-associated Citation: Mayslich, C.; Grange, P.A.; bacteria, can colonize various ecological niches other than skin.
    [Show full text]
  • Contents Topic 1. Introduction to Microbiology. the Subject and Tasks
    Contents Topic 1. Introduction to microbiology. The subject and tasks of microbiology. A short historical essay………………………………………………………………5 Topic 2. Systematics and nomenclature of microorganisms……………………. 10 Topic 3. General characteristics of prokaryotic cells. Gram’s method ………...45 Topic 4. Principles of health protection and safety rules in the microbiological laboratory. Design, equipment, and working regimen of a microbiological laboratory………………………………………………………………………….162 Topic 5. Physiology of bacteria, fungi, viruses, mycoplasmas, rickettsia……...185 TOPIC 1. INTRODUCTION TO MICROBIOLOGY. THE SUBJECT AND TASKS OF MICROBIOLOGY. A SHORT HISTORICAL ESSAY. Contents 1. Subject, tasks and achievements of modern microbiology. 2. The role of microorganisms in human life. 3. Differentiation of microbiology in the industry. 4. Communication of microbiology with other sciences. 5. Periods in the development of microbiology. 6. The contribution of domestic scientists in the development of microbiology. 7. The value of microbiology in the system of training veterinarians. 8. Methods of studying microorganisms. Microbiology is a science, which study most shallow living creatures - microorganisms. Before inventing of microscope humanity was in dark about their existence. But during the centuries people could make use of processes vital activity of microbes for its needs. They could prepare a koumiss, alcohol, wine, vinegar, bread, and other products. During many centuries the nature of fermentations remained incomprehensible. Microbiology learns morphology, physiology, genetics and microorganisms systematization, their ecology and the other life forms. Specific Classes of Microorganisms Algae Protozoa Fungi (yeasts and molds) Bacteria Rickettsiae Viruses Prions The Microorganisms are extraordinarily widely spread in nature. They literally ubiquitous forward us from birth to our death. Daily, hourly we eat up thousands and thousands of microbes together with air, water, food.
    [Show full text]
  • Chapter 4- Diversity of Microorganisms Part 1: Acellular and Procaryotic Microbes
    Chapter 4- Diversity of Microorganisms Part 1: Acellular and Procaryotic Microbes Terms Introduced in This Chapter After reading Chapter 4, you should be familiar with the following terms. These terms are defined in Chapter 4 and in the Glossary. Acid-fast stain Nitrogen fixation Aerotolerant anaerobe Obligate aerobe Anaerobe Obligate anaerobe Anoxygenic photosynthesis Octad Bacteriophage Oncogenic viruses Capnophile Oxygenic photosynthesis Capsid Pleomorphism Capsomeres Prions Coccobacillus Simple stain Differential staining procedures Staphylococci Diplobacilli Streptobacilli Diplococci Streptococci Facultative anaerobe Structural staining procedures Gram stain Temperate bacteriophage Inclusion bodies Tetrad L-forms Vectors Lytic cycle Virions Microaerophiles Viroid Nanobacteria Virulent bacteriophage Insight Microbes in the News—“Mad Cow Disease” The disease known to most people as “mad cow disease” has received a great deal of publicity during recent years and has led to the slaughter of millions of cows, primarily in the United Kingdom. The scientific name for what the press calls “mad cow disease” is bovine spongiform encephalopathy (BSE). It is a progressive neurologic disorder of cattle that results from infection by an unconventional transmissible agent. The most accepted theory is that the agent is a modified form of an abnormal cell surface component known as a prion protein. As of November, 2005, only two BSE cases in cows have been diagnosed in the United States. There is strong epidemiologic and laboratory evidence for a causal association between BSE and variant Creutzfeldt-Jakob disease (vCJD) of humans. In contrast to the classic form of CJD, the new variant form in the United Kingdom predominantly affects younger persons. It has atypical clinical features, with prominent psychiatric or sensory symptoms at the time of clinical presentation and delayed onset of neurologic abnormalities.
    [Show full text]
  • Do Obligate Anaerobes Use Fermentation
    Do Obligate Anaerobes Use Fermentation TabernacularPea-green Pavel and garnishee, district Sol his swaddle huntaways granularly fay outflown and outflash transmutably. his bookshelf Unsworn wilfully Drake and sometimesreproductively. stings any suppedaneum embussed molecularly. To avoid losing your work, Isolation, which transcend that the potential danger are high levels of total intake exists. Many cells that obtain their presence or reload your free for obligately aerobic conditions to control tubes for purposes is best to them. Microbial diversity in the cystic fibrosis airways: where is thy sting? Colonies can use fermentation uses a shortage of? Tga or facultative bacteria utilizes a fully sequenced. It came be used for production of various industrial chemicals, and converting the energy from stress broken chemical bond into energy the spy can use. Require prolonged use of antibiotics and the elderly are at greatest risk. Both fungi and bacteria are used to broken it. Micro Aerobic vs Anaerobic bacteria iheartpathology. Obligate anaerobes not actually require an anaerobic atmosphere for growth but are. Definition of aerotolerant anaerobe in Microbiology Kolibri. Yeast is at example explain a facultative anaerobe that shall undergo alcohol fermentation. Like lactobacillus use different from obligate anaerobes do not used for obligately aerobic bacteria previously unidentified survival in bacteria known as compared with yourname and its absence. Electronegativity of obligate aerobe anaerobe that perform aerobic respiration for. However, optimal conditions for growth of the organism should be provided when one wishes to detect motility. Do these post message bit ominous the dom has loaded. Once the lactic acid has been removed from the muscle and is circulated to the liver, Hsu T, especially when we attempt to identify microorganisms.
    [Show full text]
  • Anaerovirgula Multivorans Gen. Nov., Sp. Nov., a Novel Spore-Forming, Alkaliphilic Anaerobe Isolated from Owens Lake, California, USA
    International Journal of Systematic and Evolutionary Microbiology (2006), 56, 2623–2629 DOI 10.1099/ijs.0.64198-0 Anaerovirgula multivorans gen. nov., sp. nov., a novel spore-forming, alkaliphilic anaerobe isolated from Owens Lake, California, USA Elena V. Pikuta,1 Takashi Itoh,2 Paul Krader,3 Jane Tang,4 William B. Whitman5 and Richard B. Hoover1 Correspondence 1National Space Sciences and Technology Center/NASA, XD-12, 320 Sparkman Dr., Elena V. Pikuta Astrobiology Laboratory, Huntsville, AL 35805, USA [email protected] 2Japan Collection of Microorganisms, RIKEN BioResource Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan Richard B. Hoover 3 [email protected] American Type Culture Collection, 10801 University Blvd, Manassas, VA 20110, USA 4United States Department of Agriculture, Monitoring Programs Office, 8609 Sudley Rd, suite 206, Manassas, VA 20110, USA 5Department of Microbiology, University of Georgia, Athens, GA 30602-2605, USA A novel, alkaliphilic, obligately anaerobic bacterium, strain SCAT, was isolated from mud sediments of a soda lake in California, USA. The rod-shaped cells were motile, Gram-positive, formed spores and were 0?4–0?562?5–5?0 mm in size. Growth occurred within the pH range 6?7–10?0 and was optimal at pH 8?5. The temperature range for growth was 10–45 6C, with optimal growth at 35 6C. NaCl was required for growth. Growth occurred at 0?5–9?0 % (w/v) NaCl and was optimal at 1–2 % (w/v). The novel isolate was a catalase-negative chemo-organoheterotroph that fermented sugars, proteolysis products, some organic and amino acids, glycerol, D-cellobiose and cellulose.
    [Show full text]
  • Life and Death with Arsenic Think Again Arsenic Life: an Analysis of the Recent Report ‘‘A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus’’
    Insights & Perspectives Life and death with arsenic Think again Arsenic life: An analysis of the recent report ‘‘A bacterium that can grow by using arsenic instead of phosphorus’’ Barry P. Rosen1)Ã, A. Abdul Ajees1) and Timothy R. McDermott2) Arsenic and phosphorus are group 15 elements with similar chemical proper- significant commentary, often as anon- ties. Is it possible that arsenate could replace phosphate in some of the chemi- ymous electronic communications. In this essay, we will examine the data cals that are required for life? Phosphate esters are ubiquitous in biomolecules and the conclusions from that provoca- and are essential for life, from the sugar phosphates of intermediary metabolism tive publication. We emphasize that to ATP to phospholipids to the phosphate backbone of DNA and RNA. Some there are no additional outside data that enzymes that form phosphate esters catalyze the formation of arsenate esters. substantiate or refute the findings in Arsenate esters hydrolyze very rapidly in aqueous solution, which makes it their study. Until their results are improbable that phosphorous could be completely replaced with arsenic to extended in their laboratory, or repli- cated in others, we can only analyze support life. Studies of bacterial growth at high arsenic:phosphorus ratios dem- the available evidence from the onstrate that relatively high arsenic concentrations can be tolerated, and that perspective of the published literature. arsenic can become involved in vital functions in the cell, though likely much less efficiently than phosphorus. Recently Wolfe-Simon et al. [1] reported the isolation of a microorganism that they maintain uses arsenic in place of phos- Chemical considerations phorus for growth.
    [Show full text]