Shape-shifting micro-organisms

Infra-red light can help starving micro-organisms shape-shift into forms which make it easier for them to find food.

The research is reported in the latest edition of the Royal Society of Chemistry journal Photochemical and Photobiological Sciences.

A team of Japanese and American scientists - led by Professor Robert Shiurba of Waseda University, Japan - conducted tests on the single-celled protozoa Tetrahymena thermophilia.

They believe that the shape-shifting ability might be an evolutionary adaptation that helps populations of the microbe survive lean times.

In its natural freshwater environment Tetrahymena thermophilia swims upwards, gathering near the water surface in a teeming swarm where there is more oxygen, food and light.

Professor Shiurba compared two cultures of the microbe in near starvation conditions, one of which was bathed in infra-red (IR) light.

The culture in IR light grew normally at first - but when food began to run out the cells elongated into spindles, swam 50 per cent faster than normal shaped cells and also followed much straighter trajectories towards food sources.

Professor Shiurba said: "When competition for food reaches a maximum, changing shape greatly increases a cell's odds of survival."

IR light has enough energy to affect the chemical bonds in the microbes, but not enough to completely disrupt or damage the cells.

Professor Shiurba added: "The IR region of light is one of the last to be studied biologically."

with thanks to Michael Spencelayh for the original article, to Celia Clarke for providing it in advance and to David Parker for providing the images