Microbial Classification PDF

Microbial Classification Origins of Microorganisms • NASA Basic Cell Structures • Prokaryote • microscopic, unicellular organisms, lack nuclei and membrane-bound organelles • Eukaryote • unicellular (microscopic) and multicellular, nucleus and membrane-bound organelles • Viruses - Acellular, p...

Microbial Classification Origins of Microorganisms • NASA Basic Cell Structures • Prokaryote • microscopic, unicellular organisms, lack nuclei and membrane-bound organelles • Eukaryote • unicellular (microscopic) and multicellular, nucleus and membrane-bound organelles • Viruses - Acellular, parasitic particles composed of a nucleic acid and protein Classification • Provides meaningful groupings of organisms based on evolutionary relationships. Principles of Taxonomy • Taxonomy: is the science that studies organisms to arrange them into groups, or taxa • Three separate but interrelated areas: • Identification • Process of characterizing in order to group • Classification • Arranging organisms into similar or related groups • Nomenclature • System of assigning names Classification History Classification History • Five Kingdoms - based on: - Morphology - Metabolism - Molecular Techniques Classification History • 1978 Carl Woese proposed three domains based on: • Cell wall • Membrane lipids • RNA sequence • Protein synthesis • Antibiotic sensitivity Three Domains Naming Microorganisms • Binomial nomenclature Used worldwide A system of naming organisms first proposed in the 1700s by Swedish scientist Carolus Linnaeus. • Each organism is given two Latinized names: • Genus – Capitalized • Species - lowercase • Both italicized or underlined Staphylococcus aureus (S. aureus), or Staphylococcus aureus Linnaean System Taxonomic Hierarchy King Phillip Came Over For Grasshopper Soup Microbial world Classification of Eukaryotes Classification of Prokaryotes • Prokaryotic Species – population of cells with similar characteristics • Culture- bacteria grown in lab • Clone – population of cells originated from a single cell • Strain – genetically different cell within a clone- a subgroup of bacterial species that has distinguished characteristics Escherichia coli E. coli O157:H7 Classification of Viruses • Not considered living because not composed of cells • Lack anabolic machinery • Require host cells to reproduce Classification of Viruses Unique variable classification • Disease • Small pox, measles • Location where it originated • Ebola, Newcastle virus • Host or sign of disease • Tobacco mosaic • Latin words • Coronaviridae – crown • Morphology • Capsid • Genome • RNA, DNA Classifying and Identifying Microorganisms • Classification • Placing organisms in a group of related species • Identification • Matching unknown organism with known organisms Classification of Bacteria Bergey’s Manual • Provides a reference for identifying and classifying microorganisms • First published in 1923 and updated many times • Classification first based on morphology, staining, metabolism, biochemistry, serology • More recently classification based on DNA, RNA and protein sequences Classification of Bacteria • The manual divides bacteria into 4 groups or divisions on the basis of their cell wall 1. Gram + (stain violet) 2. Gram - (destain, and are counterstained pink or reddish color) 3. Bacteria that lack a cell wall (mycoplasma) 4. organisms that have a cell wall lacking “peptidoglycan” (archaeobacteria – Now called “Archaea” Photo Credit world without microbe Classification 1 Classification 2 Prokaryote Eukaryote Dichotomous Key Bergey’s Manual nomenclature