Natural anaerobic degradation of methane and petroleum in marine sediments: geochemical gradients, degradation succession and microbial zonation

石油是碳氢化合物和其他有机物质的复杂混合物。在碳氢化合物中，烷烃、环烷烃和各种芳香族化合物占了很大一部分。在海洋环境中，石油自然地通过沉积物从更深的储层迁移，通过不同的氧化还原水平、电子受体和微生物降解过程区。因此，可降解的碳化合物从氧化还原级联的能量较低端进入微生物活性区，即，与从水柱沉降的溢油相反，即，从充氧的顶部。因此，沉积物中天然石油降解的顺序开始于厌氧过程，通过利用不同的电子受体“逆序”，并结束于有氧呼吸。鉴于这种流动方向，我们预计石油成分的自然降解序列不同于传统的实验室实验，集中在选定的生物体或富集培养物的降解能力。本项目的主要目标是调查来自不同海洋地点的完整沉积物岩心中微生物石油降解的演替，模拟两种情况：石油从沉积物底部渗出和石油从沉积物顶部溢出。此外，在石油存在下的甲烷厌氧氧化的性能将进行探索。将应用地球化学和分子生物学方法来解决石油的逐步垂直降解，并确定负责微生物。

Petroleum is a complex mixture of hydrocarbons and other organic substances. Amongst the hydrocarbons, alkanes, cycloalkanes, and various aromatic compounds make up a large fraction. In the marine environment, petroleum naturally migrates through sediments from deeper reservoirs, passing different redox levels, electron acceptors and zones of microbial degradation processes. Thereby degradable carbon compounds enter the microbially active zone from the energetically lower end of the redox cascade, i.e., from the reduced zone, in opposite to oil spills that settle from the water column, i.e., from the oxygenated top. Consequently, the order of natural petroleum degradation in sediments starts with anaerobic processes through the utilization of different electron acceptors 'in reverse order' and ends with aerobic respiration. Given this flow direction, we expect the natural degradation succession of petroleum components to differ from conventional lab experimentations that concentrate on the degradation ability of selected organisms or enrichment cultures. The main objective of this project is to investigate the succession of microbial petroleum degradation in intact sediment cores from different marine locations simulating both situations: petroleum seepage from below and oil spill from top of the sediment. In addition, the performance of anaerobic oxidation of methane in the presence of petroleum will be explored. Geochemical and molecular methods will be applied to resolve the step-wise vertical degradation of petroleum and to identify the responsible microorganism.