Processes in Microbial Ecology discusses the major processes carried out by viruses, bacteria, fungi, protozoa, and other protists—the microbes—in freshwater, marine, and terrestrial ecosystems. The book shows how advances in genomic and other molecular approaches have uncovered the incredible diversity of microbes in natural environments and unraveled complex biogeochemical processes carried out by uncultivated bacteria, archaea, and fungi. The microbes and biogeochemical processes are affected by ecological interactions, including competition for limiting nutrients, viral lysis, and predation by protists in soils and aquatic habitats. The book links up processes occurring at the micron scale to events happening at the global scale, including the carbon cycle and its connection to climate change issues. The book ends with a chapter devoted to symbiosis and other relationships between microbes and large organisms, which have large impacts not only on biogeochemical cycles, but also on the ecology and evolution of large organisms, including Homo sapiens.