Abstract

Our understanding of the role of archaea, and their significance, in the biosphere has changed substantially with recent advances in molecular techniques. Large numbers of environmental rRNA gene sequences currently flooding into GenBank illustrates that, archaea are ubiquitous and sometimes quantitatively abundant in the environment. Their importance in carbon (C) and nitrogen (N) turnover in marine ecosystems and their dominant role in ammonium oxidation in terrestrial environments has been acknowledged. Knowledge of archaea and the factors determining their metabolism has potential implications for our understanding of plant productivity, carbon sequestration, nitrogen leakage and greenhouse gas (GHG) production. To mitigate global change and rise in GHGs like methane (CH₄), nitrous oxide (N₂O) and carbon dioxide (CO₂), a multidimensional approach is needed to understand the complex processes. Particularly, we need to understand how different microbial groups participate in the GHG cycling processes. The relationship between high diversity of archaea and functionality in the terrestrial ecosystem is far less understood. This review defined two fundamental aspects of the ecological significance of the archaea. First, it highlighted the role of archaea in biogeochemical cycles of major elements, such as carbon, nitrogen and sulfur. Second, it identified their significance in the GHG cycling processes and global climate change.   

Key words: Archaea, ecology, biogeochemical cycles, greenhouse gas, climate change.