Cyanobacteria
Cyanobacteria (formerly known as blue-green algae) are a phylum of Photosynthetic bacteria found in diverse environments. They play a pivotal role in Earth’s biogeochemical cycles, particularly through oxygenic photosynthesis.
Key Characteristics
- Photosynthesis: Utilize Chlorophyll a and perform oxygenic photosynthesis, releasing Oxygen as a byproduct.
- Structure: Prokaryotic organisms; lack membrane-bound organelles like mitochondria or chloroplasts.
- Habitat: Thrive in aquatic, terrestrial, and extreme environments (hot springs, polar regions).
Geological Impact
- Great Oxidation Event (GOE): Early cyanobacterial activity significantly increased atmospheric oxygen ~2.4 billion years ago, fundamentally altering Earth’s atmosphere and enabling aerobic life.
- Stromatolites: Form layered sedimentary structures through microbial mat activity; among the earliest evidence of life on Earth.
Modern Context & Interactions
- Primary Production: Major contributors to global carbon fixation, especially in marine environments.
- Nitrogen Fixation: Certain species (e.g., Trichodesmium) fix atmospheric nitrogen, supporting nutrient-poor ecosystems.
- Blooms: Can form harmful algal blooms (HABs) producing toxins that impact aquatic life and human health.
Related Concepts
- Great Oxidation Event
- Photosynthesis
- Stromatolites
References
Note: While cyanobacteria are foundational to early Earth’s oxygenation, later terrestrial colonization by plants also significantly altered global climates. See Plant Colonization Triggered Global Cooling and First Mass Extinction for details on how plant land expansion triggered cooling and the first mass extinction ~500 Ma.