Scientists find viruses can’t stick to sea bugs in the dark

Blue-green algae, or cyanobacteria, in the seas are as vital to the survival of life on earth as the oxygen producing plants are on land. But marine bacteria are attacked by viruses, which can seriously affect their life-sustaining abilities. Scientists have now discovered that these viruses don’t work in the dark, according to research presented today (Monday, 04 April 2005) at the Society for General Microbiology’s 156th Meeting at Heriot-Watt University, Edinburgh.

Our earth’s breathable atmosphere relies on millions and millions of cyanobacteria in the seas absorbing the sun’s light and giving off oxygen, in exactly the same way as the photosynthetic plants and forests on land act as the other part of the planet’s lungs. The marine dwelling cyanobacteria are at the bottom of the food-web, using sunlight to produce oxygen and absorbing carbon dioxide, giving them food to grow and multiply.

But the whole delicate balance of the seas, and so the overall fate of the planet, relies on even smaller microbes called cyanophages – marine viruses that specifically attack and infect cyanobacteria. These phages can seriously damage the health of the cyanobacteria, and also the sea.

Researcher Ying Jia, University of Warwick, is studying these minute pests and has discovered that cyanophages depend on light to stick to their victims, and cannot function in the dark. “Understanding the function of light as one of the most important environmental factors of the phage-cyanobacteria interaction is vital,” says Ying Jia.

Cyanophages may be an important weapon against problematic algal blooms. On hot, sunny days algae can cause massive, toxic blooms, poisoning huge areas of the sea with their waste products and killing fish, sea mammals such as whales, dolphins and seals, and even humans. Control of these blooms is vital to the health of the seas.

“Research using cyanophages to control blooms of cyanobacteria must take light into consideration,” explains Ying Jia. Algal blooms can use up the oxygen in water and block out the sunlight that other organisms need to live. “If there is not sufficient light, the spread of the phage might be decreased, which could undermine the efficiency of phage treatment.”

Ying Jia hopes that the research will lead to a better understanding of the relationship between phage and cyanobacteria and so the health of the seas, but may also eventually lead to efficient methods of controlling cyanobacteria blooms in an environmentally friendly way, by using these natural viruses.