Viral impact on microbiology and geochemistry of extremely nutrient-depleted sediments

极度营养不良的海洋中环流占世界海洋的很大一部分，但迄今为止几乎没有被探索过。在IODP Exp. 329期间对这些海洋省份中最大的南太平洋环流进行了调查。在这个项目中，我们将研究病毒对微生物群落和活动的影响。将测定病毒颗粒和总细胞计数，以估计它们在地下的全球分布。我们将分离有氧和厌氧原核生物，并鉴定居住在其基因组中的噬菌体。将详细分析噬菌体的形态和系统发育多样性。研究人员将研究病毒裂解是否可以为这个营养极度枯竭的生态系统提供限制性化合物。因此，病毒是否可能是深层生物圈群落丰度和多样性的主要控制因素应该得到澄清。这些结果将与我们之前在大陆边缘地区对底栖生物病毒的研究进行比较，最终提供一个更现实的病毒对深层生物圈影响的估计。

Extremely oligotrophic mid-ocean gyres represent large parts of the world´s oceans, but were hardly explored, so far. The largest of these oceanic provinces, the South Pacific Gyre, was investigated during IODP Exp. 329. In this project, we will study the viral impact on the microbial communities and activities. Virus particles and total cell counts will be determined to estimate their global distribution within the subsurface. We will isolate aerobic and anaerobic prokaryotes and identify the prophages residing in their genomes. The morphologic and phylogenetic diversity of the phages will be analysed in detail. It will be studied whether viral lysis could provide limiting compounds to this extremely nutrient-depleted ecosystem. Thus, it should be clarified whether viruses might be the main controlling factor of the abundance and diversity of the deep biosphere communities. The results will be compared to our previous studies on benthic viruses from continental margin sites, and finally provide a more realistic estimate of the viral impact on the deep biosphere.