Chapter 10: Classification of Microorganisms

why do we need quick ID of microbes?

• diagnosis: name disease (pathogen)

• treatment: has to be specific

• prevention: education/vaccines

taxonomy

science of classification

taxonomist

scientist studies classification

taxon/taxa

class, group, category being organized or ranked by some order

phylogeny

shows evolutionary relationship between organisms in a group (similarities/differences → humans vs. apes)

taxonomic hierarchy

8 taxa ranked in some order to classify/identify living things

2 highest taxa

domain & kingdom (very broad, large groups/categories)

2 lowest taxa

genus & species (very specific, small groups)

binomial nomenclature

two-part naming system

• Genus (capital) / species (lowercase)

prokaryotic cells

1. domain archaea & domain bacteria

   1. kingdom monera

2. domain archaea: NO peptidoglycan in cell wall; EXTREME HABITAT

• thermophiles: heat

• halophiles: salt

• methanogens: produce methane gas

3. domain bacteria: YES peptidoglycan in cell wall; NORMAL HABITAT

what three words are ALWAYS related? (for test)

prokaryotes = Kingdom Monera = bacterium

eukaryotic cells

domain eukarya

1. kingom protista

2. kingdom plantae

3. kingdom fungi

4. kingdom animalia

last universal common ancestor (LUCA)

evolved into 3 different cell groups → 3 domains (2 prokaryotes + 1 eukaryote)

Kingdom Monera

• prokaryotes

• unicellular

• ex. bacterium (E.coli)

Kingdom Protista

• SIMPLEST eukaryotes

• mostly unicellular (some multicellular)

• ex. amoeba & algae

Kingdom Fungi

• eukaryotes

• yeast: warm/heat; UNIcellular

• mold: cold; MULTIcellular

Kingdom Plantae

• eukaryotes

• multicellular

• autotrophs (self feeders via photosynthesis)

Kingdom Animalia

• eukaryotes

• multicellular; complex

• heterotrophs (rely on others for food source)

autotrophs

• produce own food

• types:

  • photoautotrophs (energy from sunlight make food)

  • chemoautotrophs (energy via chemical to digest food)

• ex: plants (k. plantae), algae (k. protista)

heterotrophs

rely on consuming other organisms

• types:

  • photoheterotrophs (energy from sunlight make food)

  • chemoheterotrophs (energy via chemical to digest food)

• ex. herbivores, carnivores, omnivores

eukaryotic species (non-bacterial)

differ but closely related genetically

• several related species form genus

prokaryotic species (bacterial)

bacterial cells w/ similar characteristics

• clones: pop. of bact. cell from single parent cell (genetically identical)

• subspecies/strain/serovar: members of clone (species) NOT identical d/t genetic mutations

  • ID via letters and numbers

classification of viruses

• acellular = no domain/kingdom

• obligate intracellular parasite: must invade host cell to multiply (family “-viridae”, genus, species)

  • viral subspecies/strain

methods of classifying & ID microbes

1. morphological characteristics (shape, arrangement, size)

2. differential staining

3. biochemical tests (yes no Qs)

4. serology (study of blood serum) for strains

5. PCR (polymerase chain reaction) = DNA amplication

6. textbook/manuals: Bergey’s Manual of Determinative Bacteriology “Bible of Bacteria”