Title: Cyanobacteria
1Cyanobacteria
2Evolution
- 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!
3Cyanobacteria 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
4Green Plants
Red Algae
Bacteria
Animalia
Archeae
Fungi
Other Eukaryotes
Prokaryotes
Eukaryotes
5Cyanobacteria
Brown Algae
Green Plants
Red Algae
Diatoms
Archeae
Fungi
BOTANY
6Cyanobacteria
- Microscopic organisms
- Found in marine sediments and pelagic zone,
freshwater lakes, soils, - Live in extreme environments chemically and
temperature.
7Importance
!!!
- 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 .
8Importance
- 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
9Cyanobacteria Characteristics
- - Pigments chl a, phycobiliproteins
- - phycoerythrin
- - phycocyanin BlueGreen Color
- - allophycocyanin
- - Storage glycogen
- - Cell Walls amino acids, sugars
10Forms
- Unicell with mucilaginous envelope
- Colonies
- Filaments uniserate in a single row
- - OR - multiserate not TRUE branching when
trichomes are gt 1 in rows
11Features
Filament
Mucilaginous sheath layer of mucilage outside
of the cell wall.
12Features
- Mucilaginous Sheath
- Function protects cells from drying and
involved in gliding. - Sheath is often colored
- Red acidic
- Blue basic
- Yellow/Brown high salt
13Features
- Heterocyst thick walled cell, hollow looking.
Larger than vegetative cells. - FUNCTION provides the anerobic environment for
N fixation.
H- heterocyst
14Heterocyst
Vegetative cells
Anabaena
15Habit success due to ability tolerate a wide
range of conditions
- Marine littoral and pelagic
- Fresh Water
- Hot Springs
- Terrestrial soil flora
16Heterocyst
- 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
17Nitrogen
- Nitrogen is a limiting nutrient necessary for the
production of amino acids building blocks of
life.
18Nitrogen 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.
19Mechanisms to Separate Nitrogenase from Oxygen
- Heterocyst (spatial)
- OR
- Fix Nitrogen in the DARK but not LIGHT found in
non-heterocystic cyanobacteria (temporal)
20AEROBIC
LIGHT
- CO2 H2O -----------? CH2O (sugar) O2
- Electrons for PS1 come from PS2 which evolves
oxygen (splitting of water)
21ANAEROBIC in the presence of sulfer
- 2H2S CO2 --------? CH2O 2S H2O
- H2S is the electron donor so the reaction does
not produce oxygen.
22Advantage for Cyanobacteria
- Can live in fluctuating environments of aerobic
and anaerobic with light present.
23Cyanotoxins 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
24Movement
- No flagellae or structures to enhance movement
- Excrete mucilage jet propulsion, gliding
- Helix fibers send waves of contraction
Spirulina
25Spirulina
- filamentous
- common in lakes with high pH
- major food for flamingo populations
- commercial food source
26- Anabaena with a heterocyst
- common bloom forming species with nutrient loads
27Lyngbia martensiana
Releases chemicals causing dermatitis
28Asexual Reproduction
- - Hormogonia formation -
- - Endospore / Akinete formation -
- Fragmentation
- Exospore
29Asexual Reproduction
- Hormogonia short piece of trichome found in
filaments. It detaches from parent filament and
glides away
Hormogonia
30- Oscillatoria with hormogonia
- short pieces of a trichome that become detached
from the parent filament and glide away to form
new filament.
31Oscillatoria (filamentous) with hormogonia
32Asexual Reproduction
- Akinete thick walled resting spore
33Akinete
34Asexual 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
35Asexual Reproduction
- Fragmentation - fragmentation
36Oldest 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
37Cyanobacteria and Understanding the Past
Stromatolites Shark Bay, W. Australia
38http//www.hortilover.net/