Pioneering settlers on a distant world will require food, fuel and shelter if they are to survive, but bringing bulky supplies from Earth is far too costly.
Synthetic biology offers another option. Microbes weigh precious little, and would take up next to no space on a spacecraft, but once the mission lands - on Mars, say - they could multiply by feeding on the materials available there.
The products of their labour could provide the building blocks essential for a human settlement…
A team from Brown University in Providence, Rhode Island, and Stanford University in California showed how inserting genetic machinery from E. coli makes Anabaena [an ancient Cyanobacterium] excrete more of its energy as sugar. The team even showed that they could support colonies of other bacteria on the sugar. In theory, such microbial colonies could make oil, plastics or fuel for the astronauts.
The team…has also come up with a way to supply human settlers on Mars with bricks and mortar. They began with a bacterium called Sporosarcina pasteurii, which, unusually, breaks down urea - the principle waste product in urine - and excretes ammonium. This makes the local environment alkaline enough for calcium carbonate cements to form.
The idea is that the waste produced by astronauts could feed the microbes. The microbes, in turn, would help cement together fine rocky material on a planet’s surface to create bricks.