Image from Wikimedia Commons
For years, scientists have thought that microorganisms that use chlorophyll capture the majority of solar energy in the ocean. In the article Oceanic Bacteria Trap Vast Amounts of Light Without Chlorophyll, Abby Olena writes about a protein scientists have discovered a while back, and how recently they are discovering a pigment in it that plays a major role in photosynthesis.
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Chlorophyll is the green pigment that captures sunlight for energy. We have learned a lot about this in class, but according to this article, chlorophyll isn’t the only pigment responsible for capturing sunlight.
About 20 years ago, researchers discovered “proteorhodospins–proteins that capture light with a pigment called retinal.” These proteins play a major role in converting light to energy in microorganisms located in the ocean, especially the parts where nutrients are scarce. University of Southern California biologist Laura Gomez-Consarnau says “Chlorophyll is a big deal in the ocean, but we’re showing that this other pigment is just as important.” How proteorhodospins works is by using light to pump protons out of the cell and thus generate energy as they flow back in. Gomez-Consarnau and colleagues showed that “bacteria could use that energy to grow.” Researchers wanted to learn more about these proteins, and one of the first things they wanted to know was where they were most commonly located. They discovered that proteorhodospins were “most common in the nutrient-poor waters of the Mediterranean and tended to be more abundant where levels of chlorophyll were lower.” They also wanted to compare the amount of light trapped between chlorophyll and proteorhodospins. Their research estimated that proteorhodospins provided enough energy for microorganisms like bacteria to survive, and absorbed just as much light energy as chlorophyll-a, maybe more. “In the Mediterranean, the authors’ upper estimate of the proteorhodopsin-based solar energy captured was 107 kilojoules per meters squared per day, while chlorophyll-a in the same region topped out at 19 kilojoules.” “Proteorhodopsins’ role in the global carbon cycle is also unclear,” says Gómez-Consarnau. Thanks to climate change, “the oceans are getting warmer at the same time they are depleted in nutrients.” What this means is that probably this process will be more important in the future.
This relates to what we have learned in class because we had a unit on photosynthesis, and learned that chlorophyll was responsible for capturing sunlight for energy. However, as resembled in this article, there are other proteins and pigments that capture sunlight for energy during photosynthesis. We did not cover this in class, and this is interesting information to me; the fact that there are other pigments that capture chlorophyll for photosynthesis. Also, I did not realize that organisms like bacteria went through photosynthesis, especially in the ocean, and thought only plants did.