Unlocking the mystery behind bioluminescence

As it gets dark, we are invariably captivated by the sight of tiny, blinking insects around us.

This phenomenon displayed is known as bioluminescence. As the name hints, it is a biological process which involves a chemical reaction. At the end of the reaction, tiny spurts of light are emitted. With sunlight being in abundance, only a few insects, fungi and bacteria are found to exhibit this.

Many marine species also exhibit bioluminescence as sunlight is limited in the ocean’s deep end. This also allows them to communicate with each other for various activities. The light that bioluminescence emits has very little heat involved and hence, it is ‘cold’. The milky sea effect, the layer of light that is often seen on the sea’s surface, is due to bioluminescence of sea bacteria.

The most common colours emitted are green and blue. However, some species are found to emit infra-red and yellow as well. The main purpose of releasing the light is to ward off predators. Some species use it to display and attract potential mates while others use it to attract prey. A few species absorb the bioluminescence of other species, modify internally and re-emit light of a different colour! This is called biofluorescence. This is often used as a warning by some species when their surroundings are threatened. So, how is the light produced? The process is done through a chemical reaction that ends in emission of light. The chief chemical involved is photo protein pigment called luciferin which is oxidised by an enzyme known as luciferase. While land organisms derive oxygen for the oxidation from air, their marine counterparts depend on the dissolved oxygen in water.

In the chemical reaction, the energy molecule ATP (Adenosine triphosphate) present in the mitochondria of the cell releases  light energy as a by-product. Sometimes traces of magnesium, iron and phosphorous aid the reaction to give the characteristic colour to the emission. The proteins involved are obtained from their diet.

While the most common pigment is luciferin, some marine species generate light with aequorin, another photoprotein. Magnesium and calcium ions act as catalysts during the conversion.

Applying it in science

A lot of research has been done on bioluminescence over the past few decades. Although Aristotle and Darwin mention the nature of glowing damp wood, it was Nicholas Harvey who first detailed the findings in his monograph ‘The nature of animal light’.

Using bioluminescence products in science has been increasing steadily. For instance, genetic engineering, the compound luciferase acts as a reporter gene. Its bioluminescent nature allows scientists to trace the working of the actual gene. In biomedical engineering, an experimental cancer treatment procedure has been developed, called the ‘bioluminescence activated destruction’. In agriculture, experiments are being done to develop bioluminescent plants and crops to glow when they need water or manure.

Science is still exploring many other nuances of this wondrous phenomenon and these are only some areas where rigorous activity is taking place. The nature’s lanterns might as well be showing us a way to a more efficient and safe living.