Cyanobacteria: The Original Oxygen Producer

Recently in our AP Biology coursework we have been reviewing Photosynthesis. The reaction of light, water, and carbon dioxide and its products along with the reactions that occur in the chloroplast. Several billion years ago, a tiny photosynthetic microbe called cyanobacteria transformed Earth atmosphere into one that is suitable for life. Due to their unique ability of microorganisms being able to produce oxygen through photosynthesis that set the conditions of our world and developed complex life forms.

First Oxygenators of the Earth

Cyanobacteria are a phylum of very ancient, known as blue-green algae microorganisms that have been present on Earth for more than 2.5 billion years. These microorganisms were simple but had an extraordinary capacity that of doing oxygenic photosynthesis. Oxygenic photosynthesis refers to the activity of cyanobacteria as they utilize sunlight to convert carbon dioxide and water into glucose, in turn producing oxygen as a byproduct coming from this conversion process Schopf 224. While photosynthesis in general is an everyday process now shared among plants and algae, it was the cyanobacteria who first pioneered the performance of this oxygen-generating photosynthesis. In fact, most of Earth's atmosphere before the arrival of cyanobacteria was made up of nitrogen, carbon dioxide, and methane a very different atmosphere that would not support organisms needing oxygen. What was so new and exciting about cyanobacteria is that through their exhalation, began to fill the atmosphere with oxygen until the Earth's atmosphere dramatically changed in what has been termed the Great Oxygenation Event.

Building Block of Evolutionary Progression

This role of the cyanobacteria in creating an oxygen-dominated atmosphere permitted life forms called eukaryotes organisms with more complex cells that have a nucleus to. A high level of oxygen enabled the use of aerobic respiration in organisms, which is far more efficient than anaerobic processes . As aerobic respiration is much more efficient than anaerobic respiration, far more energy can be produced, allowing larger and more complex life forms. Without their addition to the atmosphere, plants, animals, and, finally humans would likely never have evolved. It has also been suggested that the cyanobacteria are ancestors of the higher plant chloroplasts.

Due to endosymbiosis, where an ancient cyanobacterium was taken into a bigger cell with the occurrence of symbiosis, over time this type of cyanobacterium had developed into a chloroplast which is the photosynthetic organelle within the plants Margulis. Also passed on their photosynthetic capabilities to the plants, which play an essential role in Earth's oxygen and carbon cycles today. Contemporary Relevance of Cyanobacteria Today, cyanobacteria still plays a vital role in most ecosystems but more precisely in aquatic environments. They are the basic levels of the marine and freshwater food chains, where the primary production is the field where energy from the sunlight is transferred into other organisms. Alongside the oxygen they produce, some strains of cyanobacteria can also fix the atmospheric nitrogen, therefore making the water and soil richer with compounds that plants will use as nutrients.

Today Relevance of Cyanobacteria

Today cyanobacteria continues to have a crucial part in most ecosystems but more precisely in water settings. They are the foundational levels of marine and freshwater food chains, where the primary production is the area in which energy is transferred from sunlight to other organisms. In addition to the oxygen they produce, some strains of cyanobacteria are capable of fixing atmospheric nitrogen, which helps water and soil with compounds that plants will use as nutrients.