1. Classification of Microorganisms10
Classification of Microorganisms

2. Taxonomy Taxonomy The science of classifying organisms
Provides universal names for organisms
Provides a reference for identifying organisms

3. Taxonomy
Systematics or phylogeny: The study of the evolutionary history of organisms.
All Species Inventory ( )
To identify all species of life on Earth

4. Taxonomy 1735 Plant and Animal Kingdoms
1857 Bacteria and fungi put in the Plant Kingdom
1866 Kingdom Protista proposed for bacteria, protozoa,
algae, and fungi
1937 Prokaryote introduced for cells "without a nucleus"
1961 Prokaryote defined as cells in which nucleoplasm is
not surrounded by a nuclear membrane
1959 Kingdom Fungi
1968 Kingdom Prokaryotae proposed
1978 Two types of prokaryotic cells found

5. The Three-Domain System
Table 10.1

6. The Three-Domain System
Figure 10.1

7. Table 10.2

8. Endosymbiotic Theory
Figures 10.2, 10.3

9. Source of Specific Epithet
Scientific Names
Scientific Binomial
Source of Genus Name
Source of Specific Epithet
Klebsiella pneumoniae
Honors Edwin Klebs
The disease
Pfiesteria piscicida
Honors Lois Pfiester
Disease in fish
Salmonella typhimurium
Honors Daniel Salmon
Stupor (typh-) in mice (muri-)
Streptococcus pyogenes
Chains of cells (strepto-)
Forms pus (pyo-)
Penicillium chrysogenum
Tuftlike (penicill-)
Produces a yellow (chryso-) pigment
Trypanosoma cruzi
Corkscrew-like (trypano-, borer; soma-, body)
Honors Oswaldo Cruz

10. Taxonomic Hierarchy
Figure 10.5

11. Species Definition
Eukaryotic species: A group of closely related organisms that breed among themselves
Prokaryotic species: A population of cells with similar characteristics
Clone: Population of cells derived from a single cell
Strain: Genetically different cells within a clone
Viral species: Population of viruses with similar characteristics that occupies a particular ecological niche

12. Domain Eukarya
Animalia: Multicellular; no cell walls; chemoheterotrophic
Plantae: Multicellular; cellulose cell walls; usually photoautotrophic
Fungi: Chemoheterotrophic; unicellular or multicellular; cell walls of chitin; develop from spores or hyphal fragments
Protista: A catchall for eukaryotic organisms that do not fit other kingdoms

13. Prokaryotes
Figure 10.6

14. References Bergey’s Manual of Determinative Bacteriology
Provides identification schemes for identifying bacteria and archaea
Morphology, differential staining, biochemical tests
Bergey’s Manual of Systematic Bacteriology
Provides phylogenetic information on bacteria and archaea
Based on rRNA sequencing
Approved Lists of Bacterial Names
Lists species of known prokaryotes
Based on published articles

15. Identification Methods
Morphological characteristics: Useful for identifying eukaryotes
Differential staining: Gram staining, acid-fast staining
Biochemical tests: Determines presence of bacterial enzymes
Figure 10.8

16. Figure 10.7