Cyanobacteria THE FIRST ALGAE!!!!!
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!
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
Green Plants Red Algae Bacteria Animalia Archeae Fungi Other Eukaryotes Prokaryotes Eukaryotes
Cyanobacteria Green Plants Brown Algae Red Algae Diatoms Archeae Fungi BOTANY
Cyanobacteria Microscopic organisms Found in marine sediments and pelagic zone, freshwater lakes, soils, Live in extreme environments – chemically and temperature.
!!! 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 .
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
Cyanobacteria Characteristics - Pigments – chl a, phycobiliproteins - phycoerythrin - phycocyanin * BlueGreen Color - allophycocyanin - Storage – glycogen - Cell Walls – amino acids, sugars
Forms • Unicell – with mucilaginous envelope • Colonies – • Filaments – uniserate in a single row - OR - multiserate – not TRUE branching when trichomes are > 1 in rows
Features } Filament Trichome – row of cells Mucilaginous sheath – layer of mucilage outside of the cell wall.
Features Mucilaginous Sheath – Function – protects cells from drying and involved in gliding. Sheath is often colored: Red = acidic Blue = basic Yellow/Brown = high salt
Features Heterocyst – thick walled cell, hollow looking. Larger than vegetative cells. FUNCTION – provides the anerobic environment for N fixation. H- heterocyst
Heterocyst Vegetative cells Anabaena
Habit – success due to ability tolerate a wide range of conditions • Marine – littoral and pelagic • Fresh Water • Hot Springs • Terrestrial – soil flora
Heterocyst • Larger than vegetative cells • Hollow looking • Thick walled – doesn’t allow atmospheric gas to enter. • Photosynthetically inactive • No CO2 fixation or O2 evolution • Formation of heterocysts triggered by [molybdenum] and and low [nitrogen]
Nitrogen • Nitrogen is a limiting nutrient necessary for the production of amino acids = building blocks of life.
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.
Mechanisms to Separate Nitrogenase from Oxygen • Heterocyst (spatial) OR • Fix Nitrogen in the DARK but not LIGHT – found in non-heterocystic cyanobacteria (temporal)
AEROBIC LIGHT CO2 + H2O ----------- CH2O (sugar) +O2 Electrons for PS1 come from PS2 which evolves oxygen (splitting of water)
ANAEROBIC in the presence of sulfer 2H2S + CO2 -------- CH2O +2S + H2O H2S is the electron donor – so the reaction does not produce oxygen.
Advantage for Cyanobacteria • Can live in fluctuating environments of aerobic and anaerobic with light present.
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
Movement • No flagellae or structures to enhance movement • Excrete mucilage – jet propulsion, gliding • Helix – fibers send waves of contraction Spirulina
Spirulina • filamentous • common in lakes with high pH • major food for flamingo populations • commercial food source
Anabaena with a heterocyst • common bloom forming species with nutrient loads
Lyngbia martensiana Releases chemicals causing dermatitis
Asexual Reproduction - Hormogonia formation - - Endospore / Akinete formation - • Fragmentation – • Exospore
Asexual Reproduction Hormogonia – short piece of trichome found in filaments. It detaches from parent filament and glides away Hormogonia
Oscillatoria with hormogonia • short pieces of a trichome that become detached from the parent filament and glide away to form new filament.
A - akinete H Asexual Reproduction Akinete – thick walled resting spore
A - akinete H 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
Asexual Reproduction Fragmentation - fragmentation
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
Cyanobacteria and Understanding the Past Stromatolites – Shark Bay, W. Australia