Gram - negative aerobic

Gram - negative aerobic

1. Pseudomonads

   • Pseudomonas
   • Zymomonas
   • Xanthomonas
   • Zoogloea
   • straight or curved
   • no spores
   • polar flagella
     • single
     • multiple
   • chemoorganotrophs
     • strict aerobes
   • some chemolithotrophs
   • use low-molecular-weight compounds
   • mesophiles
   • key characteristics
     • no gas formation from glucose metabolism
       • distinguish from enteric bacteria and aeromonas
     • catalase positive
     • no photosynthetic pigments
       • distinguish from nonsulfur purple bacteria

2. Curved bacteria

   • spirillum
     • chemoorgano
     • microaerophilic
     • freshwater
     • Spirillum volutans
   • Aquaspirillum
     • Aquaspirillum magnetotacticum
       • magnetotaxis
         • orient along the north-south magnetic field
       • magnetosomes
         • each cell has small crystals of magnetite (Fe3O4)
   • oceanospirillum
     • small spiral from ocean
     • habitat
       • saltwater w/ high concentration of NaCl
   • Campylobacter & Helicobacter
     • curved microaerophilic bacteria
     • campylobacter jejuni
       • enteritis human
       • campylobacter fetus
         • animal abortion
     • helicobacter pylori
       • peptic ulcer
   • Bdellovibrio
     • small and motile
     • bdell - leech
     • prey on other gram negative
     • mechanism
   • ancylobacter
     • gas vacoulate
     • heterotroph
     • unusual ring shapes
     • freshwater

3. Acetic acid/ vinegar bacteria

   • Gluconobacter
     • oxidation of glucose to gluconic acids
     • flagella
       • polar
     • citric acid cycle
       • incomplete, underoxidizer
   • Acetobacter
     • ethanol to acetic acids
     • flagella
       • Peritrichous
     • citric acid cycle
       • complete, overoxidizer
   • incomplete oxidation of sugars or alcohol to acids
   • pink disease of pineapple and rotting apples and pears
   • cause turbidity and off-flavours beverage

4. nitrogen fixing bacteria

   • azotobacter
   • Azomonas
   • Azospirillum
   • Beijerinckia
   • Derxia
   • Rhizobium
   • Bradyrhizobium
   • nitrogenase
     • reduce N2 to ammonium (NH4+)
     • induced when ammonia is depleted & by O2
     • 2 proteins
       • dinitrogenase
         • iron
       • dinitrogenase reductase
         • iron
         • molybdenum
     • alternative
       • vanadium + iron or iron only
   • free living or symbiotic
   • motile
   • non-spore forming
   • some form cysts
   • nitrogen source
     • nitrogen gas
   • mechanisms to keep O2 away
   • Habitat
     • soil
     • water
     • plant surfaces
       • rhizosphere
       • leaves (phyllosphere)

5. stalked bacteria

   • caulobacter
   • hyphomicrobium
   • polyprosthecate
   • Planctomyces
   • cytoplasmic extrusions
     • stalks
     • hyphae
     • appendages
   • prostheca/stalk
     • contains cytoplasm
     • smaller in diameter than mature cell
     • importance
       • attachment
       • increase SA:V of cell
       • greater drag
   • habitat
     • aquatic
     • many live attach to surface
     • free-floating
     • gas vesicles