MICROPARA - CLASSIFICATION AND NOMENCLATURE

• The genus name is always capitalized, while the species epithet is not.
• Smaller divisions of taxon

  • Kingdom (Not used by most bacteriologists)
  • Phylum
  • Class
  • Order
  • Family
  • Genus (plural: Genera)
  • Species (Both singular & plural)
• Species - a collection of microbial strains that share many properties and differ significantly from other groups of strains
• Species - collection of bacterial cells which share an overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly
• Strain or variety - culture derived from a single parent that differs in structure or metabolism from other cultures of that species (biovars, morphovars)
• Type - subspecies that can show differences in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype)
• Binomial nomenclature – genus and species name

  • Escherichia coli – Escherichia is the genus, and coli is the species
• Scientific names are usually taken from Latin or Greek, or latinized
• Three-Domain System

  1. Archaea
  2. Bacteria
  3. Eukarya
• Archaea – no peptidoglycan in cell wall
• Bacteria – prokaryotes with peptidoglycan in cell wall
• Eukarya – eukaryotes
• Archaea - Based primarily on rRNA sequence data, domain Archaea is divided into two phyla: Phylum Crenarchaeota and Phylum Euryarchaeota
• Phylum Crenarchaeota - Originally containing thermophylic and hyperthermophilic sulfur-metabolizing archaea
• Phylum Euryarchaeota - Contains primarily methanogenic archaea, halophilic archaea, and thermophilic, sulfur-reducing archaea
• Proteobacteria

  ●Very diverse, with all four modes of nutrition represented

  ●Grouped because of shared rRNA sequence

  ●Also has endosymbionts such as nitrogen fixers

  ●Of medical importance are the chemoheterotrophs
• Selected Bacteria Phyla – Gram-Negative

  • Chlamidiae
  • Spirochaetes
  • Bacteroidetes
  • Cyanobacteria
• Chlamidiae – grow only in eukaryotic host cells
• Spirochaetes – spiral bacteria
• Bacteroidetes – includes opportunistic pathogens
• Cyanobacteria – oxygenic photosynthetic bacteria
• Selected Bacteria Phyla – Gram-Positive

  • Firmicutes
  • Actinobacteria
• Firmicutes – low G+C content; include Bacilli (both pathogenic and non-pathogenic) and Clostridia
• Actinobacteria – genetically, high G+C content
• Cocci (singular: coccus)
• Rods / bacilli (singular: rod, bacillus)
• Vibrios (singular: vibrio)
• Spirilla (singular: spirillum)
• Spirochaetes (singular: spirochaete)
• Cocci in pairs are called diplococci

  Cocci in chains are called streptococci

  Cocci in irregular groups are called Staphylococci
• Bacilli - may be arranged in chains, branching chains, mass together, or remains attached at various angles resembling Chinese  letters
• Vibrios – rods that are slightly curved
• Spirilla – polar flagella
• Spirochaetes – axial filaments
• Eukaryotes - Classification taken from Campbell Biology (2018); The term Protist is used for eukaryotes that are not plants, animal and fungi
• Stramenophila, Alveolata, Rhizaria (SAR)
• Stramenophila

  Diatoms – photosynthetic; cell wall is glassy and contains silica
• Stramenophila

  Brown algae – photosynthetic; include many seaweeds; have brown pigment. Example is the largest alga, the kelp
• Stramenophila

  Water molds – heterotrophic; also includes parasites that cause blight in plants
• Alveolata

  Dinoflagellates – autotrophic/heterotrophic/mixotrophic; commonly known for causing red tide