Cyanobacteria

SEO Title: Cyanobacteria: Features, Photosynthesis, Nitrogen Fixation, Blooms and Ecological Importance

Category: Environment & Ecology | Biology | Microbiology

UPSC Notes

Cyanobacteria are photosynthetic bacteria that can produce oxygen through photosynthesis. They were historically called blue-green algae, although they are bacteria rather than true algae.

Key Pointers

  • Prokaryotic organisms.

  • Perform oxygenic photosynthesis.

  • Contain chlorophyll-a.

  • Some species can fix atmospheric nitrogen.

  • Nitrogen fixation occurs through specialised cells called heterocysts in certain cyanobacteria.

  • Examples:

    • Nostoc

    • Anabaena

    • Oscillatoria

  • Can form harmful cyanobacterial blooms in nutrient-rich water.

  • Excess nutrients, especially nitrogen and phosphorus, can contribute to eutrophication and blooms.

  • Some species produce toxins.

Prelims Focus: Cyanobacteria → bacteria → oxygenic photosynthesis → nitrogen fixation → heterocysts.