谈地球生物学的重要意义

地球生物学是地球科学与生命科学交叉形成的一级学科,它研究作为地球系统三大基本过程之一的生命过程,即生物圈与地球其他圈层的相互作用。不仅是地球影响生物圈,而且生物圈也影响地球系统。这种相互作用或影响,从地球历史早期到现在,是一直在协同、耦合地进行着。生命与地球环境的协同演化是地球生物学的核心。当前地球生物学发展的重点是地球微生物学。宏体生物能反映地球环境对它们的影响及它们对环境的适应,但除植物外,它们对环境的影响有限。了解生物圈与地圈双向的相互作用必须研究地球微生物学。生命科学和整个自然科学都在向微观方向发展,不断形成新的理论和技术方法。古生物学不能停留在以古动、植物学为主的阶段,而要与生命科学和整个自然科学保持同步发展。现在我们已经找到了解决微生物与地质研究相结合问题的途径。微生物功能群具有重要的地质学意义,是研究地球微生物学的突破口。地球生物学是古生物学的继承和超越。分类系统学将仍然是研究的基础,但是包含了传统古生物学的地球生物学在学科内容和技术方法上将更多地与物理、化学、生物等学科交叉融合。其结果将使古生物学在时间上更前溯,在空间上更开拓,为古生物学在地球系统科学研究和为国民经济主战场服务中开辟更广阔的前景。

激光扫描共聚焦荧光显微镜技术及其在地球生物学中的应用

光学显微镜作为生命科学研究中的必要手段,经过近400年的发展其性能已得到显著的提升。激光扫描共聚焦荧光显微镜成像技术的出现,使得生物体微观三维结构的观察成为可能,与荧光探针技术的结合更是实现了生物样品从定性到原位定量分析的质的飞跃,同时还可提供生物体微观立体的成分结构信息。本文介绍了激光扫描共聚焦显微镜和荧光探针技术的发展现状、原理及应用方案,列举了该技术在地球生物学领域的主要应用。基于此提出了激光扫描共聚焦显微镜成像技术改进的方向,指出多种显微平台技术联用对生命科学的积极效应,最终实现地球生物学的长足发展。

海底2400m下采集到微生物

如果你想要找到一些奇怪的尚未被发现的生物体,海底2 000 m以下的沉积层应该是一个不错的选择。那里的热量和压力都非常大,而食物则供不应求。研究人员如今在这一深度获得了首批微生物样本,然而它们却出乎意料的普通。这些细胞与生活在陆地上的一个不太苛刻的栖息地——森林中的土壤的微生物非常类似。

Microaerobic iron oxidation and carbon assimilation and associated microbial community in paddy soil

Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.

Mineral weathering and element cycling in soil-microorganism-plant system

Soil is an essential part of the critical zone,and soil-microbe-plant system serves as a key link among lithosphere,biosphere,atmosphere and hydrosphere.As one of the habitats with the richest biodiversity,soil plays a critical role in element biogeochemistry on the earth surface(weathered crust).Here we review the soil biological processes that are relevant to mineral weathering,element cycling,and transformation,with an emphasis on rock weathering mediated by soil microbes,plant root and the rhizosphere.

Biomarker evidence for biotic and environmental change across the Cambrian Series 2–Series 3 boundary at the Wuliu- Zengjiayan section, Guizhou, China

The Wuliu-Zengjiayan section in Jianhe County, Guizhou Province, China has been suggested as a potential Global Stratotype Section and Point(GSSP) for the defined base of Cambrian Series 3. A molecular organic geochemical study on the Cambrian Series 2Series 3 boundary interval was carried out to reveal the biotic and environmental change during this transition. The hydrocarbons extracted from the Kaili Formation were proved to be indigenous. The various geochemical proxies such as biomarker parameter, δ13Corg, atomic H/C value of kerogen, and TOC content, co-vary along with the sedimentary column, and show a quick and significant change just across the Cambrian Series 2Series 3 boundary. The less abundance of isoprenoid hydrocarbons, the relative enrichment of midchain monomethyl branched alkanes(mmb-alkanes), the relatively negative value of δ13Corg, and the higher TOC contents may suggest that the upper Cambrian Series 2 was deposited in a relatively reducing environment with a higher organic input from cyanobacteria-predominated benthic microbial mats. On the other hand, the relative enrichment of isoprenoid hydrocarbons, the less abundance of mmb-alkanes, the relatively positive value of δ13Corg, the lower TOC contents, and the lower atomic H/C values of kerogen are combined to indicate an enhanced phytoplankton production and an increased oxygen content and nutrients in the ocean during the early Cambrian Series 3, which could have benefited the explosion of the Kaili Biota. The Wuliu-Zengjiayan section may provide a typical case to understand the co-variation of marine microbe, animal, and environment.

Progress and perspective on frontiers of geobiology

Geobiology is a new discipline on the crossing interface between earth science and life science, and aims to understand the in- teraction 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 envi- ronmental 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 paleoenvi- ronmental reconstruction, and to play active roles on the Earth environmental changes via elemental biogeochemical cycles and mineral bio-transforrnations, but to be deciphered are the mechanisms of these functional groups that change paleoenvi- ronmental 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 envi- ronments. 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 coor- dinative multidisciplinary studies concerning geomicrobiology and related themes, database and modeling of biogeochemical cycles, typical geological environments, and coupling of biological, physical, and chemical processes.

Genomics,metagenomics,and microbial oceanography—A sea of opportunities

Microbial oceanography is an emerging discipline resulted from the interaction,cross-fertilization and integration of life science and ocean science.Microbial oceanography integrates the principles of marine microbiology,microbial ecology and oceanography to study the role of microorganisms in the biogeochemical dynamics of natural marine ecosystems.The application of genomics tools to study marine microbes is resulting in rapid advancements in microbial oceanography that has important implications in global carbon cycle,climate change,and ecosystem function.Here we review the application of genomics and metagenomics in microbial oceanography and suggest future directions in microbial oceanography research.

The research of typical microbial functional group reveals a new oceanic carbon sequestration mechanism——A case of innovative method promoting scientific discovery

Marine microbes are major drivers of marine biogeochemical cycles and play critical roles in the ecosystems. Aerobic anoxygenic phototrophic bacteria(AAPB) are an important bacterial functional group with capability of harvesting light energy and wide distribution, and appear to have a particular role in the ocean's carbon cycling. Yet the global pattern of AAPB distribution was controversial at the beginning of the 21 st century due to the defects of the AAPB enumeration methods. An advanced time-series observation-based infrared epifluorescence microscopy(TIREM) approach was established to amend the existing AAPB quantitative deviation and led to the accurate enumeration of AAPB in marine environments. The abundance of AAPB and AAPB% were higher in coastal and continental shelf waters than in oceanic waters, which does not support the idea that AAPB are specifically adapted to oligotrophic conditions due to photosynthesis in AAPB acting a supplement to their organic carbon respiration. Further investigation revealed that dependence of AAPB on dissolved organic carbon produced by phytoplankton(PDOC) may limit their competition and control AAPB distribution. So, the selection of carbon sources by AAPB indicated that they can effectively fractionate the carbon flow in the sea. Enlightened by these findings, the following studies on the interactions between marine microbes and DOC led to the discovery of a new mechanism of marine carbon sequestration—the Microbial Carbon Pump(MCP). The conceptual framework of MCP addresses the sources and mechanism of the vast DOC reservoir in the ocean and represents a breakthrough in the theory of ocean carbon sequestration.