Gizmodo had this interesting story about an architeture student with a dramatic proposal. He suggests that we use a bacterium, bacillus pasteurii, to convert sand into sandstone in the Sahara. In the proposal, discussed at some length in this blog post, the bacterium would create a 6,000 km long wall of sandstone, halting expansion of the Sahara and creating habitable areas in the process. As Gizmodo points out, there are some significant questions that would need to be answered before trying this. For example, how do we stop the bacterium once it's going? And what would putting this enormous wall across the desert due to the climate of the rest of the world?

This is hardly the first time this type of use (sand -> sandstone) has been proposed for this bacterium. Last year, it was suggested that this same process could be used to reduce earthquake damage in areas with sandy soil. In the target article, it is pointed out that the structure of the soil does not change, meaning that buildings and other structures and the surface, even the subsurface, would be left intact and not notice a difference. What the bacteria do is fill in the gaps between grains of sand with calcium carbonate. The basic conversion process appears to have been the result of work by microbioligists at the Soil Interactions Laboratory, particularly a collaboration between UC Davis researchers and UMass Amherst researchers. The particular project home page lays it out in great detail.

Something none of these appear to mention (in my admittedly hurried review) is that this same process might be useful for terraforming planets with sandy environments. Perhaps Mars? Right now we're trying to learn about Mars without contaminating it, but if the bacterium stabilizes sand and could be made to produce oxygen, maybe we have a magic terraforming pill that would change Mars into a more human-friendly environment? And then, once we've created enough sandstone, we can redirect the bacteria to produce electricity.