現代海洋極端環境微生物的地質作用及其分子和同位素響應年度報告

王風平　彭方　黃英　湯凱

摘 要：圍繞現代海洋極端環境條件下微生物分布特征和環境因子相互關系的研究在前期工作積累的基礎上進行了更深入的分析，通過對北極冰川前沿和西南印度洋深海微生物資源的調查，初步了解了微生物群落結構的多樣性及微生物的部分生態功能，為探索地質歷史時期的微生物生命過程提供了良好的資源；發現西南印度洋深海微生物群落結構與鈣、磷、硫等元素具有相關性，為揭示深海微生物的地球化學循環創造了條件；對深海環境鐵還原菌的研究對探討古海洋環境與生命的協同演化具有重要意義。開展了微生物對模擬環境條件如海洋酸化及火山爆發等地球歷史時期的重大地質突變事件為背景，在現代海洋環境中進行了一系列的模擬研究，針對目前研究相對薄弱的環節，重點研究了海洋酸化及火山灰添加對浮游異養細菌的影響，初步揭示了浮游細菌對大氣CO2升高及火山爆發事件的反饋，完善了地質突變期海洋生態系統反饋的認識。另外，在深部生物圈MCG古菌的研究上取得了重要進展。MCG是迄今為止發現分布最為廣泛的一類未培養古菌，被認為是海底深部生物圈中最豐富，并且最活躍的類群之一，很可能在全球物質和能量循環過程中發揮了重要的作用。課題組發現MCG古菌在系統發育上處于一個深的分支，代表了一類自然界較古老的古菌，顯著不同于目前分類已確定的所有古菌門類，并提議將MCG古菌歸類于一個全新的門類，命名為深古菌門（Bathyarchaeota）。這是目前首個由中國學者提議的古菌門的分類，是古菌和生命起源和演化研究的重要進展之一，也將為該領域的科學研究起到積極推動作用。

關鍵詞：海洋 極端環境 微生物 地質作用 同位素

Abstract： We conducted further investigations on the microbial distribution characteristics and its relation with environmental factors， mainly on Actic ice front area and South-west Indian deep ocean. Our results revealed the dynamic microbial community structures and the ecological functions of some microbial groups， thus provided precious biological materials to explore the geological functions of microorganisms in the Earth history. Meanwhile， the microbial structure in the South-west Indian deep ocean was found to be related with some elements including Calcium、Phosphorus、and Sulfur， providing data and research basis for further scientific studies on revealing the biogeochemical roles of marine microorganisms. We conducted a series of environmental simulating experiments such as marine acidification and volcanic eruption which represent important geological events in the earth history. We focused on the responses of planktonic heterotrophic bacteria towards marine acidification and supplementing with volcanic ashes， our study supplements current understanding on the responses of marine ecosystem in the geological disrupting events. Moreover， we have made significant progresses on MCG archaea in the deep subsurface biosphere. MCG is one of the most widely distributed cosmopolitan uncultivated archaea， regarded as the most abundant and active archaeal group. MCG is probably playing important roles in the biogeochemical roles on Earth. We found that MCG is placed in a deep branch on the phylogenetic tree， representing an ancient group of archaea， and distinct from all known archaeal Phylum. Therefore， we propose to name MCG as a novel archaeal Phylum as “Bathyarchaeota". Proposing of MCG into a new archaeal phylum would stimulate research interests in this unknown fascinating archaeal group.

Key Words： Ocean； Extreme environments； Microorganism； Geological function； Isotope

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