Transcript Chapter 9
Jacquelyn G. Black Microbiology: Principles and Explorations Sixth Edition Chapter 9: An Introduction to Taxonomy: The Bacteria Copyright © 2005 by John Wiley & Sons, Inc. Carolus Linnaeus (1707-1778) Taxonomy • The science of classification • Provides an orderly basis for the naming of organisms • Places organisms into a category or taxon (plural: taxa) • Carolus Linnaeus: 18th century Swedish botanist; the Father of Taxonomy Binomial Nomenclature • The system used to name all living things • The first name designates the genus (plural: genera) and its first letter is capitalized • The second name is the specific epithet, and it is not capitalized • Together the genus and specific epithet identify the species The Meaning of the Names of Some Microorganisms • Escherichia coli: Named after Theodore Escherich in 1888; found in the colon • Entamoeba histolytica: Ent, intestinal; amoebae, shape/movement; histo, tissue; lytic, lysing or digesting tissue • Strain: A subgroup of a species with one or more characteristics that distinguish it from other members of the same species Classification of Human Dog Wolf and a Bacterium Using a Taxonomic Key • Dichotomous Key: A commonly used key to identify organisms. • Has paired statements describing characteristics of organisms. • Figure 9.4 Dichotomous Key for Classifying U.S. Coins Dichotomous Key for Classifying Major Bacterial Groups The Five Kingdom Classification Some Typical Monerans Archaeobacteria— Extremophiles able to exploit the unusual habitat of a “black smoker” vent Some Typical Protists Some Typical Fungi Kingdom Animalia Proposed Major Evolutionary Lines of Descent Theory About Three Domains The Three Domains • A new category even higher than kingdom • Archaea • Bacteria • Eukarya The Three Domain System of Classification The Shrub of Life Lateral Gene Transfer Bacteria vs. Archaea • Both have cell walls, however, archaea lack peptidoglycan • Bacteria have fatty acids present in their membranes; archaea have isoprenes • Bacteria lack histones ; archaea have histone-like proteins associated with the chromosome Criteria for Classifying Bacteria • Criteria for Classifying Bacteria • Table 9.4 • Biochemical Tests for ID of Bacteria: • Table 9.5 • Sugar fermentation • Starch hydrolysis • IMViC Categories of Viruses Stromatolite Mats Fossil Stromatolite Cross Section Filamentous Cyanobacteria-Paleolyngbya Probable Evolutionary Tree Arrived at by Numerical Taxonomy DNA Sequencer DNA Hybridization Separation of Proteins Phage Typing David H. Bergey (1860-1937) The Life Cycle of a Chlamydia • Small, dark elementary bodies (EB) attach to a host cell and enter by phagocytosis • The EB, enclosed within a membrane-enclosed vacuole, lose their thick walls and enlarge to form reticulate bodies (RB) • RB replicate and fill the cell • RB condense to form infectious EB and are released by lysis of the host cell Chlamydia Life Cycle