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AN INTRODUCTION TO TAXONOMY: THE BACTERIA

CHAPTER 9

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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 characteristics that distinguish it from other subgroups of the same species.

Escherchia coli ML3-, K12, 0157:H7 Table 9.1.

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I. Using Taxonomy Key:classification Hierarchy, Fig 9.4

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Tools of Taxonomy

Dichotomous keys

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Problem in Taxonomy

Phylogenetic or evolutionary relationshipWhat constitutes a species, or what

constitutes a kingdom?

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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

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5 Kingdom Classification

R. H. Whittaker 1969

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Kingdom Monera

Kingdom Monera

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Archaeans

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Kingdom Protista

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Kingdom Fungi Kingdom Fungi

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Kingdom Plantae

Chlorophylls Chloroplasts Plant-Microbes Interactions Plant pathogens quinine

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Kingdom Animalia

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The Evolution of Procaryotic organisms

Stromatolites: fossilized photosynthetic photosynthetic procaryotes: age of microorganisms. Life started 4 billion years.

Archaeobacteria: extreme environmentMethanogensExtreme halophilesextremethermophiles

Domain

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The Tree of Life is Replaced by a Shrub

Figure 9.13, 9.14. Universal common ancestor? Bacteria and archaea Eukarya branch fro archaea?

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3 Domain Classification: Carl Woese, G. F. Fox, 1976

Bacteria Archaea Eukarya

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Table 9.3. bacteria, eukarya and archaea Compared

Figure 9. 13

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Evolution

“Tree” versus “Shrub”

Lateral gene transfer

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Virus Classification No Kingdoms

Classification characteristics– Morphology

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THE SARCH FOR EVOLTIONARY RELATIONSHIPS

Single Chromosome Megaplasmid Brucella suis Mesoploidy Special Methods needed for prokaryotes: most ancestral prokaryotes disappeared.

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Taxonomic Methods Numerical Taxonomy

Genetic Homology Base Composition DNA and RNA Sequencing DNA hybridization Protein profiles and Amino Acid

SequencesPolyacrylamide gel electrophoresis(PAGE) Protein sequencing

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Taxonomic Methods Ribosomal gene

sequencing

Immunology

Phage typing

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Significance of FindingsDivergent evolution

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Bacterial Taxonomy

Classification Table 9.5 Table 9.6

Identification Type strain American Type

Culture Collection

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Bergey and His Manuals: 1923