Cyanobacteria and Smarties
We have a lot to thank the cyanobacteria for, but for me there are two main reasons. First, no oxygen would in our atmosphere if it weren’t for these little creatures. Second: blue Smarties.
Cyanobacteria are microscopic bacteria that have inhabited our planet for about 3 billion years. They existed before animals walked the Earth, before plants grew from the soil, and before algae floated in the seas. Today they are among the most common bacteria and can live in most habitats, on water, on land and even in the desert.
What gave them a big advantage, compared to the earliest life forms on Earth, is their ability to perform photosynthesis. Cyanobacteria contain a blue photo reactive pigment that can absorb energy from sunlight and use it to produce nutrients for the cell. During this process, water molecules are broken down into oxygen and hydrogen atoms, with oxygen released to the air.
In the early days of life, the Earth was populated by anaerobic bacteria that didn’t need oxygen to survive. Then cyanobacteria appeared and started engaging in photosynthetic reactions, releasing large amounts of oxygen to the atmosphere. This led to what is known as the ‘Great Oxygenation Event’, which took place around 2.5 billion years ago. If you thought that the biggest ecological catastrophe in history was the asteroid that likely killed the dinosaurs, think again. As far as we know, the Great Oxygenation Event induced by cyanobacteria’s photosynthesis was probably the largest extinction of life forms to ever have taken place on the planet. Trillions of anaerobic bacteria were suddenly asphyxiated by the presence of oxygen and wiped off the face of the Earth.
However, life goes on, but in an oxygen rich environment. Discreetly, cyanobacteria have continued to thrive in the oceans, rivers, soil – pretty much every place where water could be found. And as a result of the oxygen produced, vertebrates were able to colonise the land, trees grew hundreds of feet high and mammals evolved one after the other into more complex creatures. Fifty thousand years ago, a new species of naked ape started to populate the continents. And this particular animal – man – had a particularly sweet tooth.
We love sugar, and over time have developed increasingly sophisticated ways of consuming it. In 1882, in the city of York, sugarcoated sweets were manufactured under the name of ‘Chocolate Beans’. They came to be known for their eight colours: red, orange, yellow, green, blue, violet, pink and brown. But in 2006, due to health concerns, all chemical dyes were removed from the market and replaced by natural colourants. Unfortunately, a natural blue dye couldn’t be found and the much-loved blue Smartie was replaced by plain white.
Needless to say, Smarties fans weren’t happy. Thankfully, in 2008 the manufacturers found a way to produce a safe and natural blue dye to put the missing sweet back into the market – the natural photosynthetic blue pigment of cyanobacteria spirulina, found in seaweed!
So for glorious return of the blue Smarties, and our oxygen, children and adults have cyanobacteria to thank. But this is not the end of the story. Scientists think that cyanobacteria could be used to start a second Great Oxygenation Event… on a new planet. Terraforming a planet like Mars using bacteria to produce oxygen might sound like science fiction, but as any Star Trek or Jules Verne fan knows, fiction has preceded real science on many occasions. Someday, in the not-too-distant future we may be thanking cyanobacteria once again.
This is an edited version of Greta’s original essay. Views expressed are the author’s own.
Over the next couple of months, we’re publishing the shortlisted essays from the 2012 competition. Read all, and the 2011 essays, in our archive.