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Cyanobacteria
Matt, Alex, Megan
Characteristics
• Photosynthetic autotrophs
• Get their name from the blue pigment phycocyanin which they use to capture light for photosynthesis.
• Use the Calvin Cycle as a photosynthetic pathway, just as eukaryotic, higher plants.
• Previously referred to as “blue green algae, but are not eukaryotic algae.
Characteristics Continued
• Can fix and convert inert nitrogen to organic forms in heterocysts.
Characteristics Continued
• Cell walls containing peptidoglycan add strength and counteract osmotic pressure from cytoplasm.
• Depending on the environment, cyanobacteria colonies form filaments, sheets, or hollow balls.
• Prokaryotic with an elaborate system of internal membranes useful in photosynthesis—Chlorophyll A and phycobilins (accessory pigments) are embedded in these membranes.
• Larger than most other bacteria and have remained morphologically similar for billions of years.
History
• 1st oxygenic phototrophs on earth
• Stromatolites: 3.5 billion years
• Endosymbiotic Theory
Classification
• Phylogeny poorly understood
• 35-71% GC; 38-46% in heterocyst formers
• Define by: colony morphology, reproduction, cell morphology, genetics, habitat, ecology
• Bergey’s 2nd edition gave:– 57 genera within 5 subgroups
Classification Continued
Examples
• Oscillatoria: causes Red Sea color
• Spirulina: food source high in protein
• Anabaena: symbiosis with Azolla fern
• Lyngbya: “swimmers itch”
Metabolism
• Autotrophic so they produce their own food from simple raw materials.
• Heterocysts allow atmospheric nitrogen to be convert in the anaerobic environment
• Photosynthesis plays vast role in reproduction and growth.
-The wavelength of light absorbed determines what form will grow along with phosphate and iron consumption.
Reproduction
• Can reproduce many ways:
-Binary fission-DNA is duplicated and divided in half. - Budding-Smaller cells form from larger ones. -Fragmentation-Fragments regenerate into complete organism• Many ways of reproduction explains the various
appearances Cyanobacteria can have. Ie.) slimy masses, strings, filaments, branched
filaments…
Habitat
• Freshwater
• Wastewater
• Marine
• Terrestrial
• Adaptations– Gliding Motility– Gas Vesicles
Hot Springs
Current Research
• Wirtz, Nora et al. “Lichen fungi have low cyanobiont selectivity in maritime Antartica.” New Phytologist. 2003. 160: 177-183.
• Price, G.D. et al. “Identification of an SulP-type bicarbonate transporter in marine cyanobacteria.” PNAS. 2004. 101(52): 18228-18233
The EndHello My Name Is
Jeff