Various Pigment Types of Synechococcus Cyanobacteria from Across the World's Oceans

Studies have been done by the University of Warwick that show that bacteria that are crucial to ocean life can shift their color like chameleons to match different colored light across the world’s seas. This is a very intriguing concept, but also very amazing too. It is found that blue light is prevalent in the open ocean (obviously), while green light is prevalent in coastal and equatorial waters. Red light is prevalent in estuaries. The bacteria Synechococcus cyanobacteria contains specific genes that allow it to adapt their pigments to the light sources that are available! Therefore, this bacteria that lives in the open ocean has adapted to take in primarily blue light, whereas the bacteria in estuaries take in red light and bacteria in coastal and equatorial waters take in green light. S. cyanobacteria uses light to capture carbon dioxide from the air and produce energy for the marine food chain. Their genes are altered in such a way so as to thrive in any part of the world’s oceans.

Figure 1: SEM of Synechococcus cyanobacteria

The light that is absorbed is determined by a multitude of factors. One is the tilt of the Earth and the direction of the light from the sun to the Earth. Refraction plays a role to the bending of light. The geography also seems to play into part of the reason as to the light absorbance changes. Blue light is most prevalent in the open ocean, as it penetrates into the deep waters (it is the deepest penetrating wavelength). The prevalence of light changes depending where on the planet you go. In estuaries, says researcher David Scanlan, the light is often red, whereas in warm equatorial and coastal waters, the light is more green. The bacteria have adapted to utilize the changing light intensities to produce efficiently around the globe.

Figure 2: Various pigment types of Synechococcus cyanobacteria from across the world's oceans, grown in culture at the University of Warwick

Scanlan and colleagues analyzed specific gene sequences from S. cyanobacteria in the different water samples from around the globe. What they found was the same genes in bacteria living thousands of miles apart around the globe. The genes are known as “chromatic adaptor” genes, and they are abundant in ocean dwelling S. cyanobacteria which enables “these color-shifting microorganisms to change their pigment content in order to survive and photosynthesize in ocean waters.” If the same bacteria is in the open oceans, warm equatorial waters, coastal waters, and in estuaries, being able to efficiently produce oxygen from carbon dioxide is a useful adaptation. It would be seemingly wasteful to spend more energy in coastal waters or even estuarine waters to photosynthesize blue light if it isn’t the most prevalent light wavelength. The same goes with trying to photosynthesize red light in the equatorial waters, or green light in the open ocean.

Scanlan says that “finding [these bacterial] cells capable of dynamically changing their pigment content in accordance with the ambient light color … gives us a much deeper understanding of those processes essential to keep the ocean ‘engine’ running.” It is understood that paying attention to these microorganisms will help us better predict how the oceans will react in the future to a changing climate with increasing levels of carbon dioxide. If anything, these “key primary producers are potentially excellent bio-indicators of climate change.”

Source for Article:

https://www.eurekalert.org/pub_releases/2018-02/uow-ob022118.php 

Source for Figure 1: 

https://www.sciencesource.com/archive/Synechococcus-Cyanobacteria--SEM-SS2582898.html#/SearchResult&ITEMID=SS2582898