NASA Astrobiology

Written byAaron GronstalSourceScience

Image showing an orange glow in the lowest layer of the Earth's atmosphere. This glow comes from the Sun, which is just below the horizon. The Moon glows softly at the top center of the image as the orange light fades to blue and then the black of space.

The Sun is just below the horizon in this photo and creates an orange-red glow above the Earth’s surface. The Sun is and has been one of the most important energy sources for life on Earth since the advent of photosynthesis. Credit: NASA Johnson Space CenterImage credit: NASA Johnson Space Center.

A study of 41 genomes from uncultured microorganisms provides new information about the evolution of aerobic respiration in Cyanobacteria. Photosynthetic Cyanobacteria are thought to have changed the course of life’s evolution on Earth by playing an important role in the oxygenation of Earth’s atmosphere roughly 2.3 billion years ago. By examining the genomes of multiple Cyanobacteria, as well as other related bacterial lineages, researchers found evidence that photosynthesis likely evolved in Cyanobacteria multiple times. In addition, modern photosynthesis could have arisen from the fusion of two different photosynthetic systems via lateral gene transfer. The work provides important details about how and when cyanobacteria evolved to release oxygen via photosynthesis.

The paper, “On the origins of oxygenic photosynthesis and aerobic respiration in Cyanobacteria,” was published in the journal Science. The work was supported in part by NASA Astrobiology through the Exobiology & Evolutionary Biology Program.

Evolutionary History of Photosynthetic Cyanobacteria