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AN INTRODUCTION TO TAXONOMY: THE BACTERIA. CHAPTER 9. I.Taxonomy. Definition The science of classification. Taxon (taxa): category Carolus Linnaeus (1707-1778) Binomial Nomenclature
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I.Taxonomy • Definition • The science of classification. • Taxon (taxa): category • Carolus Linnaeus (1707-1778) • Binomial Nomenclature • Strains: subgroup of species with one or more characteristicsthat distinguish it from other subgroups of the same species. • Escherchia coli ML3-, K12, 0157:H7 • Table 9.1.
Tools of Taxonomy • Dichotomous keys
Problem in Taxonomy Phylogenetic or evolutionary relationship What constitutes a species, or what constitutes a kingdom?
Developments since Linnaeus’s Time • 1866 Ernst H. Haeckel: Protista: Simple forms of Life, bacteria, many algae, protozoa, multicellular fungi and sponges . • 1937 Procaryotes and Eukaryotes • 1957 Bergey’s Manual of Determinative Bacteriology. • 1956 Lynn Margulis and H. F. Copeland • 4 kingdoms system of classification: • 1. Monera: Bacteria, blue-green algae • 2. Protocista: algae, protozoa, fungi • 3.Plantae: • 4.Animalia • 1962 C. B. Van Niel and R. Stanier: Definition of Bacteria
5 Kingdom Classification • R. H. Whittaker • 1969
Kingdom Monera • Kingdom Monera
Kingdom Fungi • Kingdom Fungi
Kingdom Plantae • Chlorophylls • Chloroplasts • Plant-Microbes Interactions • Plant pathogens • quinine
The Evolution of Procaryotic organisms Stromatolites: fossilized photosynthetic photosynthetic procaryotes: age of microorganisms. Life started 4 billion years. Archaeobacteria: extreme environment Methanogens Extreme halophiles extremethermophiles Domain
The Tree of Life is Replaced by a Shrub • Figure 9.13, 9.14. • Universal common ancestor? • Bacteria and archaea • Eukarya branch fro archaea?
3 Domain Classification: Carl Woese, G. F. Fox, 1976 • Bacteria • Archaea • Eukarya
Table 9.3. bacteria, eukarya and archaea Compared • Figure 9. 13
Evolution • “Tree” versus “Shrub” • Lateral gene transfer
Virus Classification • No Kingdoms • Classification characteristics • Morphology
THE SARCH FOR EVOLTIONARY RELATIONSHIPS • Single Chromosome • Megaplasmid • Brucella suis • Mesoploidy • Special Methods needed for prokaryotes: • most ancestral prokaryotes disappeared.
Taxonomic Methods • Numerical Taxonomy • Genetic Homology • Base Composition • DNA and RNA Sequencing • DNA hybridization • Protein profiles and Amino Acid Sequences Polyacrylamide gel electrophoresis (PAGE) • Protein sequencing
Taxonomic Methods • Ribosomal gene sequencing • Immunology • Phage typing
Significance of Findings Divergent evolution
Classification Table 9.5 Table 9.6 Identification Type strain American Type Culture Collection Bacterial Taxonomy