The Pioneers
Well, it would seem that bacteria hold the keys to worlds, for better or for worse. That is, they have the power to change planets for the sake of our colonisation, or to the detriment of ecosystems, as recent research has shown that they may have played a role in the Permian extinction.
At the Lunar and Planetary Science conference, which took place on Tuesday, NASA scientists proposed that cyanobacteria may be usable to extract nutrients and other minerals out of the lunar soil, allowing plants to be grown and other materials to be extracted. (More) This could very well enable lunar colonisation to happen quicker and cheaper than it otherwise might.
Lunar "terraforming" using cyanobacteria would also act as its own experiment, shedding light on how cyanobacteria (and other 'extremophiles') have affected the evolution of life on earth, and indeed, other planets.