Microbiology: Cyanobacteria track water in desert soils

Cyanobacteria develop as large, cryptic populations in the topsoil of arid land, where plant cover is restricted, water is scarce and harsh microenvironmental conditions prevail. Here we show that some cyanobacteria can actively move in response to wetting or drying events by migrating to the soil surface or retreating to their refuge below. This ability to follow water, which to our knowledge has not been demonstrated before in microbes, may turn out to be important for microbial terrestrial populations in general.