Blue Green Algae-Cyanobacteria

							Blue Green Algae-Cyanobacteria
Blue Green Algae-Cyanobacteria
  Blue-Green Algae Characteristics
• Cyanobacteria-Not true
  algae
• Evolutionary precursors
  to algae and plants
• Oldest known fossils
  (3.5 billion years old)
• More than 1500 species
• Very diverse-many
  shapes, sizes and colors
  (despite blue-green
  name)
           Characteristics cont.
• Photosynthetic
  autotrophs
• Thought to be
  responsible for
  converting atmosphere
  to oxygen rich
  environment
• Live in
  rivers, lakes, damp
  soil, tree trunks, hot
  springs
• Make up “pond scum”
             Characteristics cont.
• Unicellular, many are
  colonial
• Most occur in short
  filaments-cells
  surrounded by
  gelatinous sheath
• Filamentous colonies
  have heterocysts:
   – Food storage
   – Spore forming
   – Nitrogen fixing
        Not True Algae Because…
• No chloroplasts-
   – Contain chlorophyll and
     accessory pigments in
     cytoplasm for
     photosynthesis
• Very small-size of bacteria
• No nucleus
• Cell wall does not contain
  cellulose
• Reproduce asexually
  through fission
               Nitrogen Fixing
• Some Cyanobacteria
  can convert
  atmospheric nitrogen
  (N2) into organic
  nitrogen (nitrate or
  ammonia)
• Used by plants to make
  proteins and nucleic
  acids-obtained from soil
• Heterocysts provide
  anaerobic environment
  for nitrogen fixing (no
  O2 present)
     Symbiosis and Cyanobacteria
• Legumes and other plants
  have symbiotic relationship
• Plants house the bacteria in
  specialized tissue-bacteria
  provide organic nitrogen
• Used in cultivation of rice
   – Floating fern (Azolla) is
     planted in rice paddies
     that houses
     cyanobacteria
     (Anabaena). Makes
     nitrogen for both fern
     and rice
          Endosymbiotic Theory
• Cyanobacteria were
  engulfed by larger
  prokaryotic cells
• Became the
  chloroplasts in plant
  and algae cells
            Uses of Cyanobacteria
• Spirulina
   – Used as a high protein
     food source for tropical
     countries
   – Used as a “health food”
     in the US
• Biofuel
   – Scientists are trying to
     grow and harvest BG
     algae for it’s high lipid
     content to use as
     renewable biodiesel
     source
 Dangers of Cyanobacteria Blooms
• Blooms in summer
• Bacteria creates
  powerful toxin
• Can cause:
  –   Skin and eye irritation
  –   Gastrointestinal upset
  –   Liver and nerve toxicity
  –   Poisoning of
      pets, livestock and
      wildlife