Classification of Microbes

• Systematics studies the diversity of life (both past and present) and the relationships among living things through time.
• Taxonomy is the science of biological classification: describing, identifying, classifying, and naming.
• Classification is the grouping of organisms into taxa based on mutual similarity or evolutionary relatedness.
• Identification is the characterization of an isolate to determine what species it is.
• Assignment of names to taxonomic groups in agreement with published rules is called nomenclature.
• The International Code of Nomenclature of Bacteria (ICNB) governs bacterial nomenclature.
• Microbial strain is a population of organisms that descend from a pure culture isolate or from a species.
• The main basis for the three-domain system of classification is the rRNA sequence because it is highly conserved among organisms.
• rRNA sequence is used to determine genetic relatedness and evolutionary history.
• An advantage of artificial classification is that it is stable compared to natural/phylogenetic classification.
• Artificial classification is based on expressed characteristics or phenotype.
• The disadvantages of artificial classification include:

  • Only a few characters considered
  • Not similar hereditary pattern
  • Difficult to identify specific genera or species
  • Provides limited information
  • Not related phylogenetically
• Natural classification is based on phylogenetic relatedness and shared common ancestor based on alleged evolution.
• The advantages of natural classification are:

  • Include most characters
  • Similar hereditary pattern
  • Easier identification
  • Provide plenty of information
  • Based on phylogenetic relatedness
• Disadvantage of natural classification is that it may change with advancement in knowledge.
• Which type of microorganism uses carbon dioxide and inorganic chemicals, as carbon and energy source respectively?

  Answer: Chemolithoautotroph
• What do you call an organism that takes up non-living organic nutrients in dissolved form and usually grows on decomposing organic matter?

  a.Photosynthetic

  b.Autotrophic

  c.Saprophytic

  d.Saprozoic

  Answer: C. Saprophytic