Microbes are the most abundant and diverse cellular life forms on Earth and colonize a wide range of environmental niches.However,more than 99％of bac-terial and archaeal species have not been obtained in pure culture[1]and we have only glimpsed the surface of this myste-rious microbial world.This is so-called Microbial Dark Matter(MDM):the enormous diversity of yet-uncultivated microbes that microbiologists can only study by using cultivation-independent techniques.