DOCSLIB.ORG

Expression of the Bacillus Cereus Emetic Toxin Cereulide and Its Action

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Expression of the Bacillus Cereus Emetic Toxin Cereulide and Its Action TECHNISCHE UNIVERSITÄT MÜNCHEN Lehrstuhl für Mikrobielle Ökologie The Bacillus cereus toxin cereulide: Quantification and its biological actions Tobias Christian Bauer Vollständiger Abdruck der von der Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften genehmigten Dissertation. Vorsitzender: Univ.-Prof. Dr. M. Schemann Prüfer der Dissertation: 1. Univ.-Prof. Dr. S. Scherer 2. Univ.-Prof. Dr. M. Ehling-Schulz (Veterinärmedizinische Universität Wien/Österreich) Die Dissertation wurde am 29.03.2012 bei der Technischen Universität München eingereicht und durch die Fakultät Wissenschaftszentrum Weihenstephan für Ernährung, Landnutzung und Umwelt am 26.07.2012 angenommen. “CE SONT LES MICROBES, QUI AURONT LE DERNIERE MOT” Louis Pasteur (1822-1895) Contents I CONTENTS Contents .................................................................................................................................................. i List of Figures ....................................................................................................................................... v List of Tables ..................................................................................................................................... vii Publications ......................................................................................................................................... ix Summary .............................................................................................................................................. xi Zusammenfassung ......................................................................................................................... xiii 1. Introduction and Research Objectives ................................................................................... 1 1.1 Bacillus cereus and its Pathogenicity .............................................................................................. 1 1.2 Depsipeptides .......................................................................................................................................... 2 1.3 Cereulide and its Toxicity ................................................................................................................... 3 1.3.1 Biosynthesis ..................................................................................................................................... 3 1.3.1 Structure and Characteristics ................................................................................................... 4 1.3.2 Known Biological Actions ........................................................................................................... 4 1.3.3 Severe Case Reports...................................................................................................................... 5 1.4 Principle of Stable Isotope Dilution Analysis (SIDA) ............................................................... 7 1.5 Research Objectives .............................................................................................................................. 9 2. Materials and Methods ............................................................................................................. 11 2.1 Organisms and Growth Conditions ............................................................................................... 11 2.1.1 B. cereus Strains ............................................................................................................................ 11 2.1.2 Bacterial Growth Conditions for B. cereus ......................................................................... 12 2.1.3 Chemicals & Materials ................................................................................................................ 12 2.2 DNA Isolation And Transformation .............................................................................................. 14 2.2.1 Plasmid Isolation .......................................................................................................................... 14 2.2.2 Transformation of DNA ............................................................................................................. 14 2.3 Identification of Cereulide via HPLC............................................................................................. 14 2.4 Development of a Quantification System for Cereulide ....................................................... 15 2.4.1 Biosynthetic Production of Cereulide and 13C6-Cereulide........................................... 15 2.4.2 Preparative Purification via HPLC System ........................................................................ 16 2.4.3 Sample Clean-Up and HPLC-MS/MS Analysis of Cereulide in Rice ......................... 17 2.4.4 LC-MS /MS ...................................................................................................................................... 17 2.4.5 Quantitative Analysis of Cereulide in Food Samples ..................................................... 18 2.4.6 Calibration ...................................................................................................................................... 18 | i Contents I 2.4.7 Method Validation .......................................................................................................................19 2.4.8 Investigations of Matrix Effects ..............................................................................................19 2.4.9 LC/Time-of-Flight Mass Spectrometry (LC/ESI-TOF-MS) ..........................................19 2.4.10 NMR Spectroscopy ....................................................................................................................19 2.5 Effect of Cereulide on Other Organisms ......................................................................................20 2.5.1 Antimicrobial Activity ................................................................................................................20 2.5.2 Cytotoxicity Assay ........................................................................................................................20 2.5.3 Antiparasitic Activity ..................................................................................................................21 2.5.4 Galleria mellonella as Model Host .........................................................................................22 2.5.4.1 Toxin Injection Experiments ...............................................................................................22 2.5.4.2 Analysis of ces Promotor Activity in G. mellonella ......................................................22 2.6 Intoxication Studies with Pigs .........................................................................................................23 2.6.1 Experimental Animals and Design of Study ......................................................................23 2.6.2 Clinical Parameters and Sampling ........................................................................................23 2.6.3 Histological Analyses ..................................................................................................................24 2.6.4 Blood Analysis ...............................................................................................................................24 2.6.5 Immunological Analysis ............................................................................................................24 2.6.5.1 Isolation of Porcine PBMCs from Blood Samples ........................................................24 2.6.5.2 Defrosting of Isolated PBMCs ..............................................................................................25 2.6.5.3 Flow Cytometric (FCM) Staining ........................................................................................25 2.6.5.4 FCM Analysis ..............................................................................................................................25 2.6.6 Cereulide Quantification by SIDA ..........................................................................................26 2.7 Action on Enteric Nervous System ................................................................................................27 2.7.1 Preparation of Stomach .............................................................................................................27 2.7.2 Measurement of Muscle Activity ...........................................................................................27 2.7.3 Evaluation of Muscle Activity ..................................................................................................28 3. Results ............................................................................................................................................ 29 3.1 Cereulide Isolation and Production ..............................................................................................29 3.1.1 Isolation of Cereulide..................................................................................................................29 3.1.2 Optimising of Culture Conditions for Cereulide Production ......................................30 3.1.3 Purification of Cereulide ...........................................................................................................31 3.2 Development
Load more

Recommended publications
  • The Food Poisoning Toxins of Bacillus Cereus
    toxins Review The Food Poisoning Toxins of Bacillus cereus Richard Dietrich 1,†, Nadja Jessberger 1,*,†, Monika Ehling-Schulz 2 , Erwin Märtlbauer 1 and Per Einar Granum 3 1 Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig Maximilian University of Munich, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; [email protected] (R.D.); [email protected] (E.M.) 2 Department of Pathobiology, Functional Microbiology, Institute of Microbiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; [email protected] 3 Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. Box 5003 NMBU, 1432 Ås, Norway; [email protected] * Correspondence: [email protected] † These authors have contributed equally to this work. Abstract: Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.
    [Show full text]
  • Identification of Mrna As Biomarker of Bacillus Weihenstephanensis Acid Resistance : Toward the Integration of Omic Data Into Predictive Microbiology Noemie Desriac
    Identification of mRNA as biomarker of Bacillus weihenstephanensis acid resistance : toward the integration of Omic data into predictive microbiology Noemie Desriac To cite this version: Noemie Desriac. Identification of mRNA as biomarker of Bacillus weihenstephanensis acid resistance : toward the integration of Omic data into predictive microbiology. Microbiology and Parasitology. Université de Bretagne occidentale - Brest, 2013. English. NNT : 2013BRES0096. tel-02152918 HAL Id: tel-02152918 https://tel.archives-ouvertes.fr/tel-02152918 Submitted on 11 Jun 2019 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. présentée par THÈSE / UNIVERSITÉ DE BRETAGNE OCCIDENTALE sous le sceau de l’Université européenne de Bretagne Noémie DESRIAC pour obtenir le titre de Préparée à ADRIA Développement et au DOCTEUR DE L’UNIVERSITÉ DE BRETAGNE OCCIDENTALE Laboratoire Universitaire de Biodiversité et Mention : Microbiologie Alimentaire d'Ecologie Microbienne École Doctorale SICMA Thèse soutenue le 04 Juillet 2013 Identification d’ARNm devant le jury composé de :
    [Show full text]
  • Assesment and Control of Bacillus Cereus Emetic Toxin in Food
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Helsingin yliopiston digitaalinen arkisto Assessment and control of Bacillus cereus emetic toxin in food Elina Jääskeläinen Department of Applied Chemistry and Microbiology Division Microbiology University of Helsinki Academic dissertation in Microbiology To be presented, with the permission of the Faculty of Agriculture and Forestry of the University of Helsinki, for public criticism in Auditorium 2041 at Viikki Biocenter, Viikinkaari 5, on February 1th, 2008, at 12 o´clock noon Helsinki 2008 Supervisor: Prof. Mirja S. Salkinoja-Salonen Department of Applied Chemistry and Microbiology Faculty of Agriculture and Forestry University of Helsinki Helsinki, Finland Reviewers: Prof. Willem M. de Vos 1) Laboratory of Microbiology Agrotechnology and Food Sciences Group Wageningen University and Research Centre Wageningen, the Netherlands 2) Department of Basic Veterinary Sciences Faculty of Veterinary Medicine University of Helsinki Helsinki, Finland Dr. Christophe Nguyen-The Institute of Plant Products Technology French National Institute for Agricultural Research (INRA) University of Avignon Avignon, France Opponent: Prof. Jacques Mahillon Laboratory of Food and Environmental Microbiology Université Catholique de Louvain Louvaine-la-Neuve, Belgium ISNN 1795-7079 ISBN 978-952-10-4458-8 (hardback) ISBN 978-952-10-4459-5 (PDF) Yliopistopaino Helsinki, Finland 2008 Front cover: Boys evaluating Mother`s art of cooking To my family Contents: List of original
    [Show full text]
  • Cereulide and Valinomycin, Two Important Natural Dodecadepsipeptides with Ionophoretic Activities
    Polish Journal of Microbiology 2010, Vol. 59, No 1, 310 MINIREVIEW Cereulide and Valinomycin, Two Important Natural Dodecadepsipeptides with Ionophoretic Activities MAGDALENA ANNA KROTEÑ, MAREK BARTOSZEWICZ* and IZABELA WIÊCICKA Department of Microbiology, Institute of Biology, University of Bia³ystok, wierkowa 20B, 15-950 Bia³ystok, Poland Received 2 July 2009, revised 20 December 2009, accepted 5 January 2010 Abstract Cereulide produced by Bacillus cereus sensu stricto and valinomycin synthesized mainly by Streptomyces spp. are natural dodecadepsipeptide ionophores that act as potassium transporters. Moreover, they comprise three repetitions of similar tetrapeptide motifs synthesized by non- ribosomal peptide synthesis complexes. Resemblances in their structure find their reflections in the same way of action. The toxicity of valinomycin and cereulide is an effect of the disturbance of ionic equilibrium and transmembrane potential that may influence the whole organism and then cause fatal consequences. The vlm and ces operons encoding valinomycin and cereulide are both composed of two large, similar synthetase genes, one thioestrase gene and four other ORFs with unknown activities. In spite of the characterization of valinomycin and cereulide, genetic determinants encoding their biosynthesis have not yet been clarified. Key words: Bacillus cereus, cereulide, valinomycin, ionophore Introduction lar hydrolytic enzymes and at least two third of known antibiotics (Omura et al., 2001). While cereulide, also The life and growth of both prokaryotic
    [Show full text]
  • Detection and Isolation of Emetic Bacillus Cereus Toxin Cereulide by Reversed Phase Chromatography
    toxins Communication Detection and Isolation of Emetic Bacillus cereus Toxin Cereulide by Reversed Phase Chromatography Eva Maria Kalbhenn 1, Tobias Bauer 1, Timo D. Stark 2 , Mandy Knüpfer 3, Gregor Grass 3 and Monika Ehling-Schulz 1,* 1 Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; [email protected] (E.M.K.); [email protected] (T.B.) 2 Chair of Food Chemistry and Molecular Sensory Science, Technical University of Munich, Lise-Meitner-Straße 34, 85354 Freising, Germany; [email protected] 3 Bundeswehr Institute of Microbiology, Neuherbergstraße 11, 80937 Munich, Germany; [email protected] (M.K.); [email protected] (G.G.) * Correspondence: [email protected] Abstract: The emetic toxin cereulide is a 1.2 kDa dodecadepsipeptide produced by the food pathogen Bacillus cereus. As cereulide poses a serious health risk to humans, sensitive and specific detection, as well as toxin purification and quantification, methods are of utmost importance. Recently, a stable isotope dilution assay tandem mass spectrometry (SIDA–MS/MS)-based method has been described, and an method for the quantitation of cereulide in foods was established by the International Organization for Standardization (ISO). However, although this SIDA–MS/MS method is highly accurate, the sophisticated high-end MS equipment required for such measurements limits the method’s suitability for microbiological and molecular research. Thus, we aimed to develop a method for cereulide toxin detection and isolation using equipment commonly available in microbiological and biochemical research laboratories. Reproducible detection and relative quantification of cereulide Citation: Kalbhenn, E.M.; Bauer, T.; was achieved, employing reversed phase chromatography (RPC).
    [Show full text]
  • Bacillus Cereus Spores and Cereulide in Food-Borne Illness
    Recent Publications in this Series: SHAHEEN RANAD 13/2009 Liliya Euro Electron and Proton Transfer in NADH:Ubiquinone Oxidoreductase (Complex I) from Escherichia coli 14/2009 Dario Greco Gene Expression: From Microarrays to Functional Genomics 15/2009 Elena Gorbikova Oxygen Reduction and Proton Translocation By Cytochrome c Oxidase Bacillus cereus 16/2009 Mari J. Lehtonen Rhizoctonia Solani as a Potato Pathogen - Variation of Isolates in Finland and Host Response 17/2009 Kristiina Kaste Transcription Factors ∆FosB and CREB in Drug Addiction: Studies in Models of Alcohol Preference and Chronic Nicotine Exposure Illness in Food-Borne and Cereulide Spores 18/2009 Mari K. Korhonen Functional Characterization of MutL Homologue Mismatch Repair Proteins and Their Variants 19/2009 Heidi Virtanen Structure-Function Studies of GDNF Family Ligand–RET Signalling 20/2009 Solveig Sjöblom Quorum Sensing in the Plant Pathogen Erwinia carotovora subsp. carotovora 21/2009 Tero Närvänen Particle Size Determination during Fluid Bed Granulation — Tools for Enhanced Process Understanding 22/2009 Kaisa Nieminen Cytokinin Signalling in the Regulation of Cambial Development 23/2009 Marja Pummila Role of Eda and Troy Pathways in Ectodermal Organ Development 24/2009 Anna Alonen Glucuronide Isomers: Synthesis, Structural Characterization, and UDP-glucuronosyltransferase Screening 25/2009 Päivi Lindholm Novel CDNF/MANF Protein Family: Molecular Structure, Expression and Neurotrophic Activity 26/2009 Jelena Mijatovic Bacillus cereus Spores and Cereulide in Role of
    [Show full text]
  • Pathometabolism of Emetic Bacillus Cereus
    REVIEW published: 14 July 2015 doi: 10.3389/fmicb.2015.00704 Food–bacteria interplay: pathometabolism of emetic Bacillus cereus Monika Ehling-Schulz1*, Elrike Frenzel1† and Michel Gohar2 Edited by: 1 Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Beiyan Nan, Vienna, Austria, 2 INRA, UMR1319 Micalis, AgroParistech – Domaine de Vilvert, Génétique Microbienne et Environnement, University of California, Berkeley, USA Jouy-en-Josas, France Reviewed by: George-John Nychas, Bacillus cereus is a Gram-positive endospore forming bacterium known for its wide Agricultural University of Athens, Greece spectrum of phenotypic traits, enabling it to occupy diverse ecological niches. Although Pendru Raghunath, the population structure of B. cereus is highly dynamic and rather panmictic, production Dr. VRK Women’s Medical College, India of the emetic B. cereus toxin cereulide is restricted to strains with specific genotypic Learn-Han Lee, traits, associated with distinct environmental habitats. Cereulide is an ionophoric Monash University Malaysia, Malaysia dodecadepsipeptide that is produced non-ribosomally by an enzyme complex with an Jacques Mahillon, Université Catholique de Louvain, unusual modular structure, named cereulide synthetase (Ces non-ribosomal peptide Belgium synthetase). The ces gene locus is encoded on a mega virulence plasmid related to *Correspondence: the B. anthracis toxin plasmid pXO1. Cereulide, a highly thermo- and pH- resistant Monika Ehling-Schulz, Functional Microbiology, Institute molecule, is preformed in food, evokes vomiting a few hours after ingestion, and was of Microbiology, Department shown to be the direct cause of gastroenteritis symptoms; occasionally it is implicated of Pathobiology, University in severe clinical manifestations including acute liver failures.
    [Show full text]
  • Structure Revision of Isocereulide A, an Isoform of the Food Poisoning Emetic Bacillus Cereus Toxin Cereulide
    molecules Article Structure Revision of Isocereulide A, an Isoform of the Food Poisoning Emetic Bacillus cereus Toxin Cereulide Veronika Walser 1, Markus Kranzler 2 , Monika Ehling-Schulz 2 , Timo D. Stark 1,* and Thomas F. Hofmann 1 1 Food Chemistry and Molecular Sensory Science, Technical University of Munich, Lise-Meitner-Str. 34, 85354 Freising, Germany; [email protected] (V.W.); [email protected] (T.F.H.) 2 Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria; [email protected] (M.K.); [email protected] (M.E.-S.) * Correspondence: [email protected]; Tel.: +49-8161-71-2911 Abstract: The emetic Bacillus cereus toxin cereulide presents an enormous safety hazard in the food industry, inducing emesis and nausea after the consumption of contaminated foods. Additional to cereulide itself, seven structurally related isoforms, namely the isocereulides A–G, have already been elucidated in their chemical structure and could further be identified in B. cereus contaminated food samples. The newly performed isolation of isocereulide A allowed, for the first time, 1D- and 2D-NMR spectroscopy of a biosynthetically produced isocereulide, revealing results that contradict previous assumptions of an L-O-Leu moiety within its chemical structure. By furthermore applying posthydrolytical dipeptide analysis, amino acid and a-hydroxy acid analysis by means of UPLC-ESI- TOF-MS, as well as MSn sequencing, the structure of previously reported isocereulide A could be corrected. Instead of the L-O-Leu as assumed to date, one L-O-Ile unit could be verified in the cyclic Citation: Walser, V.; Kranzler, M.; Ehling-Schulz, M.; Stark, T.D.; dodecadepsipeptide, revising the structure of isocereulide A to [(D-O-Leu-D-Ala-L-O-Val-L-Val)2(D- Hofmann, T.F.
    [Show full text]
  • Sub-Emetic Toxicity of Bacillus Cereus Toxin Cereulide on Cultured Human Enterocyte-Like Caco-2 Cells
    Toxins 2014, 6, 2270-2290; doi:10.3390/toxins6082270 OPEN ACCESS toxins ISSN 2072-6651 www.mdpi.com/journal/toxins Article Sub-Emetic Toxicity of Bacillus cereus Toxin Cereulide on Cultured Human Enterocyte-Like Caco-2 Cells Andreja Rajkovic 1,*, Charlotte Grootaert 2, Ana Butorac 3, Tatiana Cucu 2, Bruno De Meulenaer 2, John van Camp 2, Marc Bracke 4, Mieke Uyttendaele 1, Višnja Bačun-Družina 3 and Mario Cindrić 5 1 Laboratory of Food Microbiology and Food Preservation, Ghent University, Ghent B-9000, Belgium; E-Mail: [email protected] 2 Laboratory of Food Chemistry and Human Nutrition, Ghent University, Ghent B-9000, Belgium; E-Mails: [email protected] (C.G.); [email protected] (T.C.); [email protected] (B.D.M.); [email protected] (J.C.) 3 Laboratory for Biology and Microbial Genetics, Faculty of Food Technology and Biotechnology, Zagreb University, Zagreb HR-10000, Croatia; E-Mails: [email protected] (A.B.); [email protected] (V.B.-D.) 4 Laboratory of Experimental Cancer Research, University Hospital Ghent, Ghent B-9000, Belgium; E-Mail: [email protected] 5 Laboratory for System Biomedicine and Centre for Proteomics and Mass Spectrometry, ―Ruđer Bošković‖ Institute, Zagreb HR-10000, Croatia; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +32-9-264-99-04; Fax: +32-9-225-55-10. Received: 2 March 2014; in revised form: 18 July 2014 / Accepted: 22 July 2014 / Published: 4 August 2014 Abstract: Cereulide (CER) intoxication occurs at relatively high doses of 8 µg/kg body weight.
    [Show full text]
  • Modeling Bacillus Cereus Growth and Cereulide Formation in Cereal-, Dairy-, Meat-, Vegetable-Based Food and Culture Medium
    fmicb-12-639546 February 16, 2021 Time: 18:40 # 1 ORIGINAL RESEARCH published: 17 February 2021 doi: 10.3389/fmicb.2021.639546 Modeling Bacillus cereus Growth and Cereulide Formation in Cereal-, Dairy-, Meat-, Vegetable-Based Food and Culture Medium Mariem Ellouze1*, Nathália Buss Da Silva2, Katia Rouzeau-Szynalski1, Laura Coisne1, Frédérique Cantergiani1 and József Baranyi3 1 Food Safety Microbiology, Food Safety Research Department, Institute of Food Safety and Analytical Sciences, Nestlé Research, Lausanne, Switzerland, 2 Laboratory of Food Microbiology, Wageningen University & Research, Wageningen, Netherlands, 3 Institute of Nutrition, University of Debrecen, Debrecen, Hungary This study describes the simultaneous Bacillus cereus growth and cereulide formation, Edited by: in culture medium and cereal-, dairy-, meat-, and vegetable-based food matrices. First, Eugenia Bezirtzoglou, Democritus University of Thrace, bacterial growth experiments were carried out under a wide range of temperatures Greece (from 9 to 45◦C), using the emetic reference strain F4810/72, in the above-mentioned Reviewed by: matrices. Then, the generated data were put in a modeling framework where the Fereidoun Forghani, response variable was a vector of two components: the concentration of B. cereus IEH Laboratories and Consulting Group, United States and that of its toxin, cereulide. Both were considered time-, temperature- and matrix- Richard Dietrich, dependent. The modeling was carried out in a series of steps: the parameters fitted Ludwig Maximilian University of Munich, Germany in one step became the response variable of the following step. Using the square root Mirjana Andjelkovic, link function, the maximum specific growth rate of the organism and the time to the Sciensano, Belgium appearance of quantifiable cereulide were modeled against temperature by cardinal *Correspondence: parameters models (CPM), for each matrix.
    [Show full text]
  • Assesment and Control of Bacillus Cereus Emetic Toxin in Food
    Assessment and control of Bacillus cereus emetic toxin in food Elina Jääskeläinen Department of Applied Chemistry and Microbiology Division Microbiology University of Helsinki Academic dissertation in Microbiology To be presented, with the permission of the Faculty of Agriculture and Forestry of the University of Helsinki, for public criticism in Auditorium 2041 at Viikki Biocenter, Viikinkaari 5, on February 1th, 2008, at 12 o´clock noon Helsinki 2008 Supervisor: Prof. Mirja S. Salkinoja-Salonen Department of Applied Chemistry and Microbiology Faculty of Agriculture and Forestry University of Helsinki Helsinki, Finland Reviewers: Prof. Willem M. de Vos 1) Laboratory of Microbiology Agrotechnology and Food Sciences Group Wageningen University and Research Centre Wageningen, the Netherlands 2) Department of Basic Veterinary Sciences Faculty of Veterinary Medicine University of Helsinki Helsinki, Finland Dr. Christophe Nguyen-The Institute of Plant Products Technology French National Institute for Agricultural Research (INRA) University of Avignon Avignon, France Opponent: Prof. Jacques Mahillon Laboratory of Food and Environmental Microbiology Université Catholique de Louvain Louvaine-la-Neuve, Belgium ISNN 1795-7079 ISBN 978-952-10-4458-8 (hardback) ISBN 978-952-10-4459-5 (PDF) Yliopistopaino Helsinki, Finland 2008 Front cover: Boys evaluating Mother`s art of cooking To my family Contents: List of original publications...................................................................................................3 The author´s contribution.......................................................................................................4
    [Show full text]
  • Cesh Represses Cereulide Synthesis As an Alpha/Beta Fold Hydrolase in Bacillus Cereus
    toxins Article CesH Represses Cereulide Synthesis as an Alpha/Beta Fold Hydrolase in Bacillus cereus Shen Tian 1,2, Hairong Xiong 3, Peiling Geng 1,2, Zhiming Yuan 1,* and Xiaomin Hu 1,* 1 Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China; [email protected] (S.T.); [email protected] (P.G.) 2 University of the Chinese Academy of Sciences, Beijing 100049, China 3 College of Life Science, South-Central University for Nationalities, Wuhan 430074, China; [email protected] * Correspondence: [email protected] (Z.Y.); [email protected] (X.H.); Tel.: +86-027-8719-8120 or +86-027-8719-8195 (X.H.) Received: 18 March 2019; Accepted: 20 April 2019; Published: 21 April 2019 Abstract: Cereulide is notorious as a heat-stable emetic toxin produced by Bacillus cereus and glucose is supposed to be an ingredient supporting its formation. This study showed that glucose addition benefited on cell growth and the early transcription of genes involved in substrate accumulation and toxin synthesis, but it played a negative role in the final production of cereulide. Meanwhile, a lasting enhancement of cesH transcription was observed with the addition of glucose. Moreover, the cereulide production in DcesH was obviously higher than that in the wild type. This indicates that CesH has a repression effect on cereulide production. Bioinformatics analysis revealed that CesH was an alpha/beta hydrolase that probably associated with the cell membrane, which was verified by subcellular localization. The esterase activity against para-nitrophenyl acetate (PNPC2) of the recombinant CesH was confirmed.
    [Show full text]