You might say blue-green algae are optimists: they put things in the best possible light—literally.  Actually, the organisms aren’t really algae. They’re photosynthetic ocean bacteria. And they can fine-tune their photosynthetic apparatus to take advantage of the predominant wavelength of light. Now researchers have figured out how one of the world’s most abundant phytoplankton control their color change.

It all comes down to a single, light-sensitive enzyme. In coastal waters where the surrounding light and water are green, specific proteins help catch green light. But in the deeper blue-colored waters, the color change activates an enzyme that replaces the green-light catching proteins with ones tuned for blue light. The finding is in the Proceedings of the National Academy of Sciences. [Animesh Shukla et al., Phycoerythrin-specific bilin lyase–isomerase controls blue-green chromatic acclimation in marine Synechococcus]

The bacteria produce 20 percent of the planet’s oxygen and also consume carbon dioxide from the atmosphere. Researchers say understanding how the bacteria optimize their photosynthesis may help inform climate change scientists. And medical researchers could also get ideas for pigments useful in medical research. Who knew pond scum could be so smart?

—Gretchen Cuda Kroen

[The above text is a transcript of this podcast.]