Artist’s impression of a bioluminescent city lit by bioluminescent plants and algae.
Illustration: Signe Friis Schack, Allumen IVS

At the Technical University of Denmark (DTU), Science reports, researchers are investigating bioluminescent algae, to determine whether bioluminescent organisms could one day light up our cities in a turquoise blue light.

There are some clear challenges to solve. The researchers say that they may need to transfer genes from bioluminescent organisms into other green organisms, perhaps higher plants that will be able to emit light more effectively.

Dinoflagellates emit a strong blue light at night. This phenomenon is known as bioluminescence, whereby living organisms produce light via chemical reactions. They are widely visible at certain times of the year in warmer climates, around the equator from Brazil to Australia.

Even though people have observed this phenomenon in the ocean for more than 2,500 years, we still know surprisingly little about the algae involved and how they produce light.

The luciferase enzyme (yellow Pacman) becomes active at pH 6. It binds with luciverin (green wedge), transferring energy via oxidation, which is emitted as blue light.
Illustration: Signe Friis Schack, Allumen IVS

The algae emit a blue light when they are shaken. Such as, when a predator swims by creating a current, or when the algae are hit by waves in coastal waters.

Two molecules are particularly important for light production: Luciferase (an enzyme) and luciferin (a molecule produced by photosynthesis).

When algae register a disturbance, a chain of cellular chemical processes is set in motion causing the pH to drop. This activates the luciferase enzymes, which bind to the luciferin and transfer energy to the luciferin via oxidation. It is the release of energy from luciferin we see as blue light.

The bioluminescent algae use sunlight to produce energy via photosynthesis to carry out a whole range of processes at the cellular level. They “recharge” during the day so they can emit their blue light throughout the night.

As long as these microalgae grow in a closed container they can function as a biological lamp, which could be used as bulbs to illuminate our cities, shop windows, buildings, roads, and carparks.

Bioluminescent algae are the first stage in the development of biological light, but there are some clear challenges when using algae in a lamp. Algae need to be disturbed into motion before they illuminate, which is problematic in a lamp. Moreover, they only illuminate for a relatively short period because of energy limitation.

To produce biological lamps that can illuminate throughout the night without movement means that we need to think along entirely new lines. Currently, the Danish researchers are trying to figure out precisely which genes are used to emit light and then transfer these genes to other photosynthetic organisms to produce a bioluminescent plant that can emit light all night long.

By: Kristian Ejlsted, MSc. in Biotechnology, Technical University of Denmark, Department of Biotechnology and Biomedicine, Henrik Toft Simonsen, Associate professor, Technical University of Denmark, Department of Biotechnology and Biomedicine.

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