Ecology and adaptations
Aquatic habitat
Freshwater and marine environments
Example organism: Synechococcus, Prochlorococcus
Adaptations
Motility or buoyancy.
- Strategies include buoyancy regulation to ensure access to sunlight (energy). Gas vesicles regulate cell buoyancy, which allows bacteria to be in a right position for optimal light conditions for photosynthesis.
- Aggregation in colonies and consortia in which there are numerous interactions with an array of microheterotrophs and invertebrate grazers.
- Close coupling of production and nutrient cycling within these communities.
- Development of endosymbioses.
- Intracellular nitrogen and phosphorus storage.
- The development of capacities for heterotrophy.
- Photoheterotrophy, and pigment adaptation to counteract potential photooxidative conditions in surface waters.
Geothermal habitat
Hot springs
Example organism: Synechococcus species
Adaptations
- Ability to withstand high temperatures up to 74°C by modification of their cell wall (greater charged amino acids), lipids, and protein compositions.
- They also have modified cellular processes.
Cold, polar habitat
Ice shelves, glaciers or glacial meltwater streams
Example organism: Nostoc, oscillatorians
Adaptations
- An ability to grow over a wide temperature range (but at slow rates).
- Tolerance of desiccation, freezing and salinity stress.
- A variety of adaptive strategies against high levels of solar radiation (including ultraviolet radiation) in exposed habitats.
- Acclimation to shade allowing net growth in protected dim light environments.
hypersaline habitat
Salt lakes, solar salterns, hypersaline lagoons or sulphur springs
Example organism: Microcoleus chthonoplustes, Aphanothece halophytica
Adaptations
- Ability to withstand the high osmotic pressure,
- Possess mechanisms to maintain osmotic equilibrium and cell turgor. Ions (Na + , K + , C1-) can temporarily enter the cells to counteract rapid increases in medium salinity, however, for the long term, organic solutes are accumulated to provide osmotic balance, as expected in organisms whose enzymatic machinery is inhibited by salt.
Soil habitat
Example organism: Nostoc
Adaptations
- Tolerance of desiccation and water stress.
- The ability to fix dinitrogen is widespread in soil cyanobacteria species with this ability having a competitive advantage where combined nitrogen levels are low.
- Many cyanobacteria tolerate high levels of ultra- violet irradiation permitting them to survive at the soil surface, whereas others photosynthesize efficiently at low photon flux densities, permitting effective photosynthesis just below the surface.
Image taken from: Colonization of wheat {Triticum vulgare L.)by Ng-fixing cyanobacteria: II.An ultrastructural study. M. GANTAR, N. W. KERBY AND P. ROWELL
other organisms
Eukaryotic hosts including plants, fungi, sponges and protists
Example organism: Nostoc
Adaptations
- As nitrogen fixing autotrophs, they provide hosts with nitrogen and carbon.
- Symbiotic cyanobacteria are filamentous.
- Fix nitrogen in heterocysts.
- Have hormogonia.
These characteristics enable them to live in symbiosis with other organisms.