Fig. 3

Sewage-based terraformation motif. In (a) we consider a situation where an artificial environment (grey box) is created as a byproduct of human activities, i.e. wastewater in sewer, and one extant organism is engineered. A simpler alternative (b) does not require engineering of extant species since it is a completely artifactual ecosystem and its preservation is not required. Our two strains are both sustained by available resource R and physical conditions (grey box) while they are growing there, but at some point all of them are removed (burned or released) at a given rate. A typical scenario would be sewage-related infrastructures (c) where a rich microbial community (d) is known to exist.