cianobactérias

Cianobactérias, commonly known as blue-green algae, are a phylum of bacteria characterized by their ability to perform oxygenic photosynthesis. This means they produce oxygen as a byproduct of converting light energy into chemical energy, similar to plants and algae. Their evolutionary history is significant, as they are believed to be responsible for the initial oxygenation of Earth's atmosphere, a pivotal event that paved the way for aerobic life.

These microorganisms are found in a wide range of environments, including freshwater, marine, and terrestrial habitats, often in soil, rocks, and even extreme conditions like hot springs and polar ice. Their morphology varies greatly; they can be unicellular, colonial, or filamentous. Some species possess specialized cells called heterocysts, which are adapted for nitrogen fixation, converting atmospheric nitrogen into a usable form for other organisms.

Cianobactérias play crucial roles in ecosystems. They are primary producers, forming the base of many food webs. Their nitrogen-fixing capabilities are vital for nutrient cycling in many environments. However, under certain conditions, such as nutrient enrichment in water bodies, some species can proliferate rapidly, forming blooms. These blooms can deplete oxygen, produce toxins harmful to aquatic life and humans, and negatively impact water quality. Despite these potential issues, cianobactérias are essential components of the biosphere.