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Microbial Diversity (Bacteria (Deinococcus-Thermus (Gram +ve; but lack…

- - - - Gram -ve; rod-shaped
      - thermophile
      - microaerophilic - requires oxygen to survive, but lower than oxygen level that present in the atmosphere (2–10% O2).
      - chemolithoautotroph - use hydrogen, thiosulfite and sulfur as electron donor; oxygen as electron acceptor
  - - - Gram -ve; rod-shaped
      - has outer sheath-like envelope
      - thermophiles (grow in active geothermal areas)
      - chemoheterotroph - have functional glycolytic pathway; grow anaerobically on carbohydrate or protein digest
  - - - outer membrane layer similar to Gram -ve
      - has L-ornithine in peptidoglycan
      - lacks teichoic acid
  - - - green sulfur bacteria
        
        thrive in sulfide rich area
        
        have chlorosomes
        
        ellipsoidal vesicles; attached to plasma membrane
        
        contain accessory photosynthetic pigments
        
        efficient light harvesting complexes
        
        non-motile; lack flagella
        
        gas vesicles (some); adjust cell depth for light / hydrogen sulfide
        
        obligate anaerobic photolithoautotrophs
        
        bacteriochlorophyll reaction in plasma membrane
        
        hydrogen sulfide, elemental sulfur and hydrogen -> electron sources
        
        elemental sulfur deposited outside cell
      - genera
        
        Chlorobium
        
        Prosthecochloris
        
        Pelodictyon
    - - green non-sulfur bacteria
        
        photosynthetic -> Chloroflexus; use unusual 3-hydroxypropionate bi-cycle to fix carbon dioxide
        
        filamentous; gliding motility
        
        thermophilic
        
        anoxygenic photosynthesis; doesn't use water as electron donor, photoheterotroph
        
        can grow aerobically as chemoheterotroph
        
        non-photosynthetic -> Herpetosiphon
        
        filamentous; gliding motility
        
        rod-shaped
        
        aerobic; chemoheterotroph with respiratory metaboilsm
        
        isolated from fresh water and soil habitats
    - - oxygenic photosynthesis (produce oxygen)
        
        2 photosystems
        
        water as electron donor
      - purple & green -> anoxygenic photosynthesis
        
        purple sulfur
        
        γ-proteobacteria family ( Chromatiaceae & Ectothiorhodospiraceae)
        
        purple non-sulfur
        
        α- and β-proteobacteria
      - Chlorophyceae -> blue-green algae
      - Gram -ve
      - most obligate photolithoautotroph; some can grow slowly in dark as chemoheterotroph
      - storage structure (some) contains
        
        carboxysomes; enzymes for Calvin cycle (Calvin cycle to fix carbon dioxide)
        
        cyanophycin; arginine, aspartic acid
      - may be unicellular, colonial or filaments (trichomes -> row of cells in close contact)
      - phycobiliproteins - accessory pigments
        
        phycobilisomes - line thylakoid membranes, contain phycocyanin (blue-green) & phycoerythrin (red / brown)
        
        prochlorophytes - lack phycobilins
      - cause bloom in nutrient-rich ponds & lakes; some produce toxin
      - form symbiotic relationship
        
        phototrophic partner in lichens
        
        symbionts with protozoa & fungi
        
        nitrogen-fixing species form plant association
  - - - has compartmentalized cells (annamoxosome); carry out anammox reaction (anaerobic ammonia oxidation)
      - cell wall lacks peptidoglycan; not a Gram -ve / Gram +ve
      - attach through stalk & holdfast (Planctomyces), others genera lack stalk; most have sessile cells bud (produce motile swarmer cells) in life cycle
    - - Gram -ve
      - obligate intracellular parasite (need host to grow & reproduce)
  - - - free living
      - symbiotic -> hindguts of termites, digestive tracts of mollusks & mammals, oral cavities of animals
      - disease -> Lyme disease & syphilis
  - - - Gram -ve rods: shape vary
      - do not form endospores
      - motile / non-motile
      - chemoheterotroph - fermentative
      - in oral cavity & intestinal tract
  - - - Rickettsiales (short, non-motile rod; aerobic; obligate intracellular parasite) & Holosporales
    - - chemoheterotroph & chemolithotroph
      - use decomposed organic matter anoxically
      - some use hydrogen, methane, ammonia volatile fatty acids
    - - chemoorganotroph, photolithotroph, chemolithotroph, methylotroph; aerobic & anaerobic
    - - aerobic, chemoorganotroph, predator
      - anaerobic, chemoorganotroph, sulfur- & sulfate-reducer
    - - Camphylobacteriales & Nautiliales
      - slender, Gram -ve, rod-shaped
      - pathogens -> deep sea bacteria
      - thermophilic; chemolithotroph
  - - - low G+C content
      - 3 classes : Clostridia, Bacilli & Negativicutes
    - - high G+C content
      - Gram +ve, aerobic
      - produce filamentous cells (hyphae); differentiate into asexual spore
      - adapt to climate (similar like fungi)
      - source of most currently used antibiotics
      - produce anti-cancer, anti-helminthic & immunosuppressive metabolites
      - most non-motile due to flagellated spores
      - mostly in soil; play roles in organic matter mineralization
      - most free living; some pathogens
- - - - Hyperthermophiles
      - Acidophiles (some)
      - Sulfur-dependent (most) - some used as electron acceptor in anaerobic respiration, some used as electron source
      - Organotroph (use organic compound as carbon source) ->
        sulfur-oxidizing
      - Lithotroph (use inorganic compound as carbon source) -> hydrogen-oxidizing
    - - Membrane lipid -> thaumarchaeol (previuosly known as crenarchaeol
      - Mesophilic (capable of nitrification; ammonia -> nitrate)
    - - 5 major groups
        
        Methanogens
        
        produce methane
        
        methanogenesis - occurs in anaerobic environments; last step of organic compound degradation
        
        oxidize iron
        
        form symbiotic relationship with certain bacteria to assist in carbon cycle
        
        Halobacteria
        
        extreme halophiles -> optimum at 3-4M NaCl; cell wall disintegrates if NaCl < 1.5M
        
        aerobic; chemoheterotroph
        
        Thermoplasms
        
        3 genera
        
        Thermoplasmataceae
        
        Picrophilaceae
        
        Ferroplasmataceae
        
        thermoacidophile
        
        lack cell wall
        
        Extremely thermophilic sulfur reducer
        
        3 genera
        
        Thermococcus
        
        Paleococcus
        
        Pyrococcus
        
        motile by flagella
        
        obligate anaerobes
        
        reduce sulfur -> sulfide
        
        Sulfate reducer
        
        irregular coccoid cells
        
        cell wall has glycoprotein subunit
        
        extreme thermophilic
        
        organotroph (lactate/glucose) / lithotroph (hydrogen)
        
        use sulfate / sulfite / thiosulfate -> electron acceptor
        
        has some methanogen coenzymes