摘要
Microbes are the oldest inhabitants of Earth. Through billions of years of coevolution with Earth, these creatures, usually invisible to the naked eye, have contributed to shaping the Earth surface, creating an ecosystem habitable for higher organisms including humans. By some estimates, microbes account for up to half of the biomass on the planet today (Whitman et al., 1998). They thrive in every corner of Earth, including harsh habitats such as hot springs, hydrothermal vents, salt and soda lakes, acid mine drainage, deep subsurface, and thus define the boundaries of the biosphere. Microbes also exhibit immense genetic and metabolic diversity. Therefore, it is not surprising that these organisms play a pivotal role in driving elemental cycling on Earth, a process essential for maintaining the habitability of the planet Earth.
