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Published Version Eawag_08805 DISS. ETH No. 20763 Occurrence, growth and competitive properties of Listeria spp. in the aquatic environment A dissertation submitted to ETH ZURICH for the degree of Doctor of Sciences presented by RUDOLF SCHNEEBELI Dipl. Natw. ETH born November 08, 1982 citizen of Zurich, Switzerland accepted on the recommendation of Prof. Dr. Thomas Egli, examiner Prof. Dr. Martin J. Loessner, co-examiner Priv. Doz. Dr. Andreas H. Farnleitner, co-examiner 2012 Table of Contents Table of Contents Summary .................................................................................................................................. V Zusammenfassung ................................................................................................................ IX List of Abbreviations ........................................................................................................... XIII 1. General Introduction ........................................................................................................ 15 History ................................................................................................................................. 15 Listeria: Taxonomy and characteristics .............................................................................. 15 Listeriosis ............................................................................................................................. 17 Two lifestyles: from environmental saprophyte to intracellular pathogen .......................... 18 Listeria infection and persistence ....................................................................................... 19 Sources, niches and possible routes of transmission of Listeria ....................................... 21 Cycling between habitats .................................................................................................... 22 Listeria in water ................................................................................................................... 24 Oligotrophs versus copiotrophs .......................................................................................... 25 Nutrient availability in water environments ......................................................................... 26 Competition between microorganisms................................................................................ 29 Objectives of this thesis ...................................................................................................... 31 References .......................................................................................................................... 32 2. Occurrence and growth of Listeria spp. in Swiss surface waters .............................. 41 Abstract ............................................................................................................................... 42 Introduction .......................................................................................................................... 43 Material & Methods ............................................................................................................. 45 Results ................................................................................................................................. 50 I Table of Contents Discussion ........................................................................................................................... 60 Conclusion ........................................................................................................................... 64 Acknowledgements ............................................................................................................. 64 Supplementary data ............................................................................................................ 65 References .......................................................................................................................... 68 3. Growth of Listeria spp. in wastewater culture and in competition with bacterial flora from wastewater .................................................................................................................... 73 Abstract ............................................................................................................................... 74 Introduction .......................................................................................................................... 75 Material & Methods ............................................................................................................. 77 Results ................................................................................................................................. 84 Discussion ......................................................................................................................... 100 Conclusion ......................................................................................................................... 104 Acknowledgements ........................................................................................................... 104 References ........................................................................................................................ 105 4. A defined, glucose-limited mineral medium for the cultivation of Listeria ............. 111 Abstract ............................................................................................................................. 112 Introduction ........................................................................................................................ 113 Material & Methods ........................................................................................................... 114 Results ............................................................................................................................... 119 Discussion ......................................................................................................................... 132 Conclusions ....................................................................................................................... 136 Acknowledgements ........................................................................................................... 137 Supplementary data .......................................................................................................... 138 References ........................................................................................................................ 139 II Table of Contents 5. Concluding remarks and outlook ................................................................................. 143 Experimental design .......................................................................................................... 143 Methods used .................................................................................................................... 145 I) Occurrence of Listeria in surface water ......................................................................... 147 II) Growth potential of Listeria spp. in surface water ........................................................ 149 III) Growth of Listeria in wastewater ................................................................................. 150 IV) Growth of Listeria in mixed bacterial cultures ............................................................. 152 V) A well-defined carbon-limited mineral medium for the cultivation of Listeria .............. 155 What has this study contributed to the knowledge about the ecology of Listeria in the environment? ..................................................................................................................... 157 Concluding remarks .......................................................................................................... 159 References ........................................................................................................................ 160 Acknowledgements ............................................................................................................ 165 Curriculum Vitae ................................................................................................................. 167 III IV Summary Summary Bacteria belonging to the genus of Listeria are Gram-positive, rod-shaped, non-spore- forming cells. They can be found ubiquitously in nature. Within this genus two species, L. monocytogenes and L. ivanovii, are of particular interest since they are described to be pathogenic to humans and animals, respectively. Frequent signs of a listeriosis, the disease caused by Listeria infection, are general flu-like symptoms and in severe cases, meningitis, encephalitis, septicaemia or stillbirth in pregnant women. With 30 to 40% the disease’s mortality rate is high, although listeriosis has a rather low incidence in human. The disease especially threatens young, old, pregnant and immunocompromised people. Ingestion of contaminated food products is the main route of infection by Listeria. In many European countries human listeriosis is reported to be a disease of increasing relevance that is becoming, due to its high mortality rate, one of the most perilous food-related infectious diseases. According to literature, L. monocytogenes can be found in several environmental systems like soil, plant material or water. Nonetheless, only little is known about the pathogen’s life in nature, and
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