About 20 years ago, researchers discovered Prochlorococcus, a photosynthetic marine microorganism. Penny Chisholm, a biologist at MIT whose work led to the discovery of the microbe, talks about its role in producing 20 percent of the oxygen in the Earth's air.
Daily programme highlights from BBC Radio News. Interviews and reports from BBC Radio 1, BBC Radio 4, BBC Radio 5 live, the BBC Asian Network and the BBC World Service.
