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Geobiology is a new discipline on the crossing interface between earth science and life science, and aims to understand the interaction and co-evolution between organisms and environments. On the basis of the latest international achievements, the new data presented in the Beijing geobiology forum sponsored by Chinese Academy of Sciences in 2013, and the papers in this special issue, here we present an overview of the progress and perspectives on three important frontiers, including geobiology of the critical periods in Earth history, geomicrobes and their responses and feedbacks to global environmental changes, and geobiology in extreme environments. Knowledge is greatly improved about the close relationship of some significant biotic events such as origin, radiation, extinction, and recovery of organisms with the deep Earth processes and the resultant environmental processes among oceans, land, and atmosphere in the critical periods, although the specific dynamics of the co-evolution between ancient life and paleoenvironments is still largely unknown. A variety of geomicrobial functional groups were found to respond sensitively to paleoenvironmental changes, which enable the establishment of proxies for paleoenvironmental reconstruction, and to play active roles on the Earth environmental changes via elemental biogeochemical cycles and mineral bio-transformations, but to be deciphered are the mechanisms of these functional groups that change paleoenvironmental conditions. Microbes of potential geobiology significance were found and isolated from some extreme environments with their biological properties partly understood, but little is known about their geobiological functions to change Earth environments. The biotic processes to alter or modify the environments are thus proposed to be the very issue geobiology aims to decipher in the future. Geobiology will greatly extend the temporal and spatial scope of biotic research on Earth and beyond. It has great potential of application in the domains of resource exploration and global change. To achieve these aims needs coordinative multidisciplinary studies concerning geomicrobiology and related themes, database and modeling of biogeochemical cycles, typical geological environments, and coupling of biological, physical, and chemical processes. [ABSTRACT FROM AUTHOR]

The biosphere interacts and co-evolves with natural environments. Much is known about the biosphere's response to ancient environmental perturbations, but less about the biosphere's influences on environmental change through earth history. Here, we discuss the roles of microbes in environmental changes during the critical Permian-Triassic (P-Tr) transition and present a perspective on future geomicrobiological investigations. Lipid biomarkers, stable isotopic compositions of carbon, nitrogen and sulfur, and mineralogical investigations have shown that a series of microbial functional groups might have flourished during the P-Tr transition, including those capable of sulfate reduction, anaerobic HS oxidation, methanogenesis, aerobic CH oxidation, denitrification, and nitrogen fixation. These microbes may have served to both enhance and degrade the habitability of the Earth-surface environment during this crisis. The integrated microbial roles have enabled the Earth's exosphere to be a self-regulating system. [ABSTRACT FROM AUTHOR]