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Microbial diversity (Bacteria (Phylum Spirochaetes (Ecologically diverse…

- - - - Glucose catabolism
      - CO2 fixation
      - Ability to synthesize methane (some)
  - - - Some are acidophiles
      - Most are strict anaerobes
      - Most are extremely thermophilic
      - Many are sulfur-dependent
        
        As electron acceptor in anaerobic respiration
        
        As electron source
    - - Organotrophs & lithotrophs (sulfur-oxidizing & hydrogen-oxidizing)
      - Contains 25 genera
        
        Best studied: Sulfolobus & Thermoproteus
  - - - Unique membrane lipid (before known as crenarchaeol, now known as thaumarchaeol)
      - Widespread in nature
    - - Nitrification (ammonia to nitrate) - characteristic metabolic feature of this phylum
      - In marine environments
  - - - Class Thermoplasmata
      - 3 different genera
        
        Picrophilaceae
        
        Ferroplasmataceae
        
        Thermoplasmataceae
      - Thermoacidophiles
      - Lack cell walls
    - - Class Thermococci
        
        One order, Thermococcales
      - 3 genera
        
        Thermococcus
        
        Paleococcus
        
        Pyrococcus
      - Motile by flagella
      - Optimum growth temperature 88 - 100 Celsius
      - Reduce sulfur to sulfide
      - Strictly anaerobic
    - - Order Halobacteriales
        
        17 genera - one family, Halobacteriaceae
      - Extreme halophiles
        
        at least 1.5 M NaCl
        
        Growth optima near 3 -4 M NaCl
      - Aerobic, respiratory, chemoheterotrophs with complex nutritional requirements
    - - Class Archaeoglobi
        
        Order Archaeoglobales
        
        3 genera including Archaeoglobus
      - Irregular coccoid cells
        
        Glycoprotein subunits in cell walls
      - Extremely thermophilic
        
        Optimum at 83 Celsius
        
        Isolated from marine hydrothermal vents
      - Metabolism
        
        Use sulfate, sulfite, or thiosulfite as electron acceptor
        
        Possess some methanogen coenzymes
        
        Lithotrophic (hydrogen) or organotrophic (lactate/glucose)
    - - Produce methane
      - Methanogenesis
        
        Last organic compound degradation step
        
        Occurs in anaerobic environments
      - 26 genera - largest cultured archaea group
      - Differ in
        
        Membrane lipids
        
        Cell walls
        
        16S rRNA
        
        Morphology
      - Ecological & practical importance
        
        Wastewater treatment
        
        Produce significant amounts of methane
        
        Used as clean burning fuel & energy source
        
        Greenhouse gas - contribute to global warming
        
        Oxidize iron - iron pipes corrosion
        
        Symbiotic relationships with certain bacteria - assists carbon/sulfur cycling
- - - - Thermophile
      - Microaerophilic
      - Gram-negative rod
      - Chemolithotroph
  - - - Gram-negative
      - Thermophiles
      - Chemoheterotrophs
  - - - 2 orders (Deinococcales & Thermales)
      - 3 genera - best studied: Deinococcus
      - One class (Deinococci)
      - Spherical or rod-shaped; in pairs or tetrads - Gram-positive (lack typical Gram-positive cell wall)
    - - Resistant to desiccation & radiation
      - Unknown natural habitat
      - Aerobic - catalase positive
  - - - Has both photosynthetic and nonphotosynthetic members
      - Genera
        
        Genus Herpetosiphon*
        
        Aerobic chemoorganotrophs with respiratory metabolism
        
        Isolated fresh water and soil habitats
        
        Non-photosynthetic, gliding, rod-shaped, or filamentous
        
        Genus Chlorofexus
        
        Filamentous
        
        Thermophilic
        
        Metabolism
        
        Anoxygenic photosynthesis
        
        Aerobic chemoheterotrophs
      - Green nonsulfur bacteria
    - - Heliobacteria
    - - One class (Chlorobia); one order (Chlorobiales); one family (Chlorobiaceae)
      - Representative genera
        
        Chlorobium
        
        Prosthecochloris
        
        Pelodictyon
      - Green sulfur bacteria
        
        Lack flagella; nonmotile
        
        Some have gas vesicles
        
        Have chlorosomes
        
        Obligate anaerobic photolithoautotrophs
        
        Thrive in sulfide rich areas
        
        Morphologically diverse
    - - Structures & arrangements
        
        Diameter: ~1 to 10 micrometer
        
        Unicellular, colonial, or filaments called trichomes
        
        Storage - carboxysomes (enzymes for Calvin cycle); cyanophycin (arginine, aspartic acid)
      - Photosynthesis (carbon fixation)
        
        Use Calvin cycle to fix CO2
        
        Accessory pigments: phycobiliproteins
        
        Phycobilisomes contain phycocyanin & phycoerythrin
        
        Prochlorophytes lack phycobilins
      - Obligate photolithoautotrophs; some can grow in dark as chemoheterotrophs
      - Pigmentation
        
        Phycoerythrin: red-brown coloration
        
        Chromatic adaptation - pigment concentrations modulation in different light
        
        Phycocyanin: appear blue-green
      - Gram-negative
      - Phototaxis - gas vacuoles
      - Largest, most diverse group of photosynthetic bacteria - Chlorophyceae (blue green algae)
      - Ecology
        
        Tolerant of environmental extremes
        
        Cause blooms in nutrient-rich ponds and lakes
  - - - Attach to surfaces - stalk & holdfast
    - - Anammoxosome compartment
    - - Lack stalk
      - Most life cycles - sessile cells bud - motile swarmer cells
  - - - Free living
      - Symbiotic
      - Disease
  - - - Terrestrial & marine environments
      - Sewage treatment plants
    - - Anaerobic, Gram-negative rods, various shapes, no endospores
      - Chemoheterotrophs - fermentative
      - Often found in
        
        Oral cavity & intestinal tract of humans & other animals
        
        Rumen of ruminants
  - - - Betaproteobacterium
      - Gammaproteobacterium
        
        Very diverse - physiologically
        
        Many deeply branching groups
      - Deltaproteobacterium
        
        2 general groups
        
        Aerobic, chemoorganotrophic predators
        
        Anaerobic, chemoorganotrophic sulfur- and sulfate-reducers
      - Alphaproteobacterium
      - Epsilonproteobacterium
        
        Smallest proteobacterial classes
        
        Slender, Gram-negative rods
        
        Range: pathogens to deep-sea bacteria
  - - - Phylum Firmicutes
        
        Clostridia
        
        Bacilli
        
        Negativicutes
    - - Phylum Actinobacteria
        
        Actinomycetes
        
        Aerobic
        
        Produce filamentous cells - hyphae - differentiate into asexual spores
        
        Adapt to climates - similar to fungi