1. Classification of Microorganisms
Putting Bugs in Boxes

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

3. Taxonomy Systematics or phylogeny All Species Inventory (2001-2025)
The study of the evolutionary history of organisms
All Species Inventory ( )
To identify all species of life on Earth

4. The Three-Domain System
Table 10.1

5. The Three-Domain System
Figure 10.1

6. Endosymbiont Theory
Figure 10.2
Figure 10.3

7. Source of Specific epithet
Scientific Names
Scientific binomial
Source of Genus name
Source of Specific epithet
Kbebsiella 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 notatum
Tuftlike (penicill-)
Spores spread in wind (nota)
Trypanosoma cruzi
Corkscrew-like (trypano-, borer; soma-body)
Honors Oswaldo Cruz

8. Taxonomic Hierarchy
Figure 10.5

9. Species Definition Eukaryotic species: Prokaryotic 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

10. 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

11. 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

12. Microbiology Lab Order
Figure 10.7