Shiny nature leads the way

A plant-like micro-organism mostly found in oceans could make the manufacture of products, from iridescent cosmetics, paints and fabrics to credit card holograms, cheaper and greener.

Small organism with big potential – diatoms could give us cheap colourful products

The tiny single-celled diatom has a hard silica shell which is iridescent - a shell displays vivid colours that change depending on the angle at which it is observed. This effect is caused by a complex network of tiny holes in the shell which interfere with light waves. UK scientists have now found an extremely effective way of growing diatoms in controlled laboratory conditions, with potential for scale-up to industrial level.

“It’s a very efficient and cost-effective process, with a low carbon footprint,” says Professor Andrew Parker, who led the research. “Its simplicity and its economic and environmental benefits could in future encourage industry to develop a much wider range of exciting products that change colour as they or the observer move position. What’s more, the shells themselves are completely biodegradable, aiding eventual disposal and further reducing the environmental impact of the process life cycle.”  

Manufacturing consumer products with these properties currently requires energy-intensive, high-temperature, high-pressure industrial processes that create tiny artificial reflectors. But farming diatom shells, which essentially harnesses a natural growth process, could provide an alternative that takes place at normal room temperature and pressure, dramatically reducing energy needs and so cutting carbon dioxide emissions. The process is also extremely rapid - in the right conditions, one diatom can give rise to 100 million descendants in a month.

The new technique, achieved by scientists at the Natural History Museum and the University of Oxford, involves taking a diatom or other living cell - such as those that make iridescent butterfly scales- and immersing them in a culture medium. By changing the precise make-up of the culture medium, the exact iridescent properties of the diatoms, and therefore the final optical effects that they create, can be adjusted. The researcher’s estimate that up to 1 tonne/day of diatoms could be produced in the laboratory in this way, starting from just a few cells. Within as little as two years, an industrial-scale process could be operational.