Cyanobacteria

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Cyanobacteria

• THE FIRST ALGAE!!!!!

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Evolution

• Old 3.5 billion years
• Dominated as biogenic reefs
• During Proterozoic Age of Bacteria (2.5 bya
  750 mya) they were wide spread
• Then multicellularity took over
• Cyanobacteria were first algae!

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Cyanobacteria terminology

• - Division Cyanophyta
• - Cyanobacteria formerly known as BlueGreen
  Algae
• - Cyano blue
• - Bacteria acknowledges that they are more
  closely related to prokaryotic bacteria than
  eukaryotic algae

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Green Plants
Red Algae
Bacteria
Animalia
Archeae
Fungi
Other Eukaryotes
Prokaryotes
Eukaryotes
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Cyanobacteria
Brown Algae
Green Plants
Red Algae
Diatoms
Archeae
Fungi
BOTANY
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Cyanobacteria

• Microscopic organisms
• Found in marine sediments and pelagic zone,
  freshwater lakes, soils,
• Live in extreme environments chemically and
  temperature.

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Importance
!!!

• 1) First organisms to have 2 photosystems and to
  produce organic material and give off O2 as a
  bi-product.
• ?Very important to the evolution of the earths
  oxidizing atmosphere .

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Importance

• 2) Many fix or convert atmospheric nitrogen
  into usable forms through Nitrogen Fixation when
  other forms are unavailable.
• IMPORTANT because atmospheric N2 is unavailable
  to most living organisms because breaking the
  triple bond is difficult

N
N
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Cyanobacteria Characteristics

• - Pigments chl a, phycobiliproteins
• - phycoerythrin
• - phycocyanin BlueGreen Color
• - allophycocyanin
• - Storage glycogen
• - Cell Walls amino acids, sugars

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Forms

• Unicell with mucilaginous envelope
• Colonies
• Filaments uniserate in a single row
• - OR - multiserate not TRUE branching when
  trichomes are gt 1 in rows

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Features

• Trichome row of cells

Filament
Mucilaginous sheath layer of mucilage outside
of the cell wall.
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Features

• Mucilaginous Sheath
• Function protects cells from drying and
  involved in gliding.
• Sheath is often colored
• Red acidic
• Blue basic
• Yellow/Brown high salt

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Features

• Heterocyst thick walled cell, hollow looking.
  Larger than vegetative cells.
• FUNCTION provides the anerobic environment for
  N fixation.

H- heterocyst
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Heterocyst
Vegetative cells
Anabaena
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Habit success due to ability tolerate a wide
range of conditions

• Marine littoral and pelagic
• Fresh Water
• Hot Springs
• Terrestrial soil flora

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Heterocyst

• Larger than vegetative cells
• Hollow looking
• Thick walled doesnt allow atmospheric gas to
  enter.
• Photosynthetically inactive
• No CO2 fixation or O2 evolution
• Formation of heterocysts triggered by
  molybdenum and and low nitrogen

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Nitrogen

• Nitrogen is a limiting nutrient necessary for the
  production of amino acids building blocks of
  life.

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Nitrogen Fixation

• ONLY cyanobacteria and prokaryotic bacteria can
  FIX nitrogen.
• Of these two only CYANOBACTERIA evolve OXYGEN
  during photosynthesis
• Important because nitrogenase (enzyme involved in
  fixing nitrogen) is INACTIVATED by O2.

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Mechanisms to Separate Nitrogenase from Oxygen

• Heterocyst (spatial)
• OR
• Fix Nitrogen in the DARK but not LIGHT found in
  non-heterocystic cyanobacteria (temporal)

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AEROBIC
LIGHT

• CO2 H2O -----------? CH2O (sugar) O2
• Electrons for PS1 come from PS2 which evolves
  oxygen (splitting of water)

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ANAEROBIC in the presence of sulfer

• 2H2S CO2 --------? CH2O 2S H2O
• H2S is the electron donor so the reaction does
  not produce oxygen.

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Advantage for Cyanobacteria

• Can live in fluctuating environments of aerobic
  and anaerobic with light present.

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Cyanotoxins in Cyanobacteria

• Neurotoxins block neuron transmission in
  muscles (Anabaena, Oscillatoria)
• Hepatotoxins inhibit protein phosphatase, cause
  liver bleeding. Found in drinking water.
  (Anabaena, Oscillatoria, Nostoc)
• Eg. swimmers itch - Lygnbia

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Movement

• No flagellae or structures to enhance movement
• Excrete mucilage jet propulsion, gliding
• Helix fibers send waves of contraction

Spirulina
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Spirulina

• filamentous
• common in lakes with high pH
• major food for flamingo populations
• commercial food source

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• Anabaena with a heterocyst
• common bloom forming species with nutrient loads

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Lyngbia martensiana
Releases chemicals causing dermatitis
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Asexual Reproduction

• - Hormogonia formation -
• - Endospore / Akinete formation -
• Fragmentation
• Exospore

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Asexual Reproduction

• Hormogonia short piece of trichome found in
  filaments. It detaches from parent filament and
  glides away

Hormogonia
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• Oscillatoria with hormogonia
• short pieces of a trichome that become detached
  from the parent filament and glide away to form
  new filament.

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Oscillatoria (filamentous) with hormogonia
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Asexual Reproduction

• Akinete thick walled resting spore

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Akinete
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Asexual Reproduction

• Akinete thick walled resting spore
• Function resistant to unfavorable environmental
  conditions.
• Appear as larger cells in the chain and different
  than heterocyst. Generally lose buoyancy

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Asexual Reproduction

• Fragmentation - fragmentation

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Oldest Fossils

• 3.5by old carbonaceous microfossils S.Africa
• 3.4by old filaments and microbial fossils W.
  Australia
• 3.4 by old stromatolites S.Africa, Australia

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Cyanobacteria and Understanding the Past
Stromatolites Shark Bay, W. Australia