He admits that it sounds like science fiction, but an ANU scientist says a "Jekyll and Hyde" bacteria that has been on Earth for more than 2.5 billion years could help humans colonise Mars and search for aliens.

Australian National University scientists have worked with research institutions in Italy, France and the UK on a study that found Chroococcidiopsis, a type of cyanobacteria, could be used to create oxygen and a biosphere to sustain human life on the red planet.

Mars, which an international team of scientists believes could one day be colonised by humans. Credit:NASA

"This might sound like science fiction, but space agencies and private companies around the world are actively trying to turn this aspiration into reality in the not-too-distant future," emeritus professor Elmars Krausz said.

"Photosynthesis could theoretically be harnessed with these types of organisms to create air for humans to breathe on Mars."