Cyanobacteria are the most environmentally significant group of bacteria on Earth. In this article in Microbiology Today, David Adams explains how in many ways life on Earth owes its very existence to this ancient group of micro-organisms:
Cyanobacteria are a huge group of photosynthetic bacteria found in almost every environment on Earth, including many of those most inhospitable to life, such as hot springs, deserts and the Antarctic. They are also enormously abundant, particularly in the oceans, and are primary producers, meaning that they fix CO2 and in many cases also N2; as a consequence they have an immense influence on the planet’s nutrient cycles and even its weather. Life on Earth owes a further great debt to this group of bacteria because their evolution of oxygenic photosynthesis, in which oxygen is released from the splitting of water, resulted in the eventual oxygenation of the atmosphere, providing the stimulus for the evolution of complex life forms. In addition, cyanobacteria are the ancestors of plastids, the photosynthetic organelles of today’s algae and plants.