Researchers in the United States have successfully utilized the mesmerizing blue luminescence produced by a marine algae species to create light-emitting structures.
Known as Pyrocystis lunula, this bioluminescent single-celled organism is capable of generating fleeting bursts of blue light. When grouped together, these algae can create stunning luminous effects as ocean waves crash against the shore.
Giulia Brachi from the University of Colorado Boulder conducted experiments in a dark lab with the aim of encouraging the algae to emit a more prolonged glow. “We were attempting to compress them very slowly,” Brachi remarked, detailing their efforts to mimic the mechanical pressure of ocean waves. “However, the algae did not respond as expected.”
While other researchers have achieved similar results using mechanical stimulation, such methods can be challenging to regulate. Consequently, Brachi and her team opted for a different approach. Previous research suggested that exposure to acidic conditions lowered the pH in the algae’s light-producing organelles, prompting illumination. They introduced a mildly acidic solution to a flask containing the algae.
“At first, I thought it was light from a laptop,” Brachi recalled, but soon realized that the algae had transformed into what appeared to be living glitter. In a study published in Science Advances, Brachi and her colleagues outlined how they managed to generate light for durations of up to 25 minutes.
The researchers encapsulated the algae in a hydrogel, a water-based jelly-like material, which enabled them to 3D-print various whimsical shapes, including a crescent moon, reflecting the algae’s appearance under microscopic observation. All the designs emitted a vibrant cyan hue.
Bioluminescent algae contain an enzyme called luciferase, which interacts with a light-emitting compound known as luciferin—the origins of these terms trace back to the Latin word for “light bearer.” “They are relatively self-sufficient as long as they have access to seawater,” explained Professor Wil Srubar, also from the University of Colorado Boulder.
Srubar proposed that this “living light” could be utilized in products such as glowsticks or luminous bracelets for events like raves. Furthermore, the algae could potentially be integrated into biosensors that illuminate upon detecting environmental toxins.
Professor Chris Howe of the University of Cambridge, who was not part of the research, commented, “Translating lab successes to practical applications in real-world settings poses a challenge, but this represents a fascinating initial step.”
He noted that for small light-emitting devices typically powered by disposable batteries, the adoption of bioluminescence could significantly minimize the waste associated with depleted batteries.
Anthony Campbell, an emeritus professor at the University of Cardiff, pointed out that the ability of certain algae to emit light when exposed to acid is well established. However, he expressed doubts about the long-term viability of the algae in the acidic solution used in the experiments, which had a pH of 4, comparable to that of a tomato. “They don’t fare well in that environment; it induces stress,” Campbell stated.
One question remains unanswered: scientists still do not fully understand why species like Pyrocystis lunula evolved to produce light. It is hypothesized that their glowing displays may serve a defensive purpose, potentially deterring predators.
Howe remarked, “This seems like a reasonable hypothesis, but it is not definitively established.”
