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