Influence of fluids from the ocean crust on growth and activity of deep-biosphere populations (IODP Leg 301)

胡安·德富卡海脊东侧的国际海洋学勘探项目1301号站点（水深：2 650米，沉积物覆盖面：265米）的沉积柱的特征是来自下伏洋壳的热液扩散流，温度梯度为0.23摄氏度/米，有两个硫酸盐-甲烷过渡区。我们的项目的一个目标是通过将电子受体引入深埋沉积物来了解流体作为海洋深层生物圈驱动力的作用。这一假设得到了细胞定量和活性测量沿着沉积柱。沉积物-基底界面处细胞数量的增加首次证明了地壳流体刺激的微生物群落。潜在的磷酸酶活性增强，在贫磷层对沉积物-基底界面。硫酸盐还原率和甲烷厌氧氧化率在较低的硫酸盐-甲烷过渡带内升高。进一步的研究集中在土著微生物的分离和表征。分子筛选，用于确定富集文化的微生物组成，从所有沉积层，揭示了不同的微生物类型。然而，由于我们处理的是缓慢生长的原核生物，它们需要长达六个月的时间才能形成一个菌落。因此，新分离株的分离和表征以及出版物的编写将在申请期结束前完成。

The sediment column of IODP Site 1301 of the eastern flank of the Juan de Fuca Ridge (water depth: 2650 m, sediment coverage: 265 m) is characterised by a diffusive flow of hydrothermal fluids from the underlying ocean crust, a steep temperature gradient of 0.23 °C/m and two sulfate-methane transition zones. One goal of our project is to understand the role of fluids as a driving force for the marine deep biosphere by introducing electron acceptors to deeply buried sediments. This hypothesis was supported by cell quantification and activity measurements along the sediment column. Elevated cell numbers at the sediment-basement interface gave the first evidence for a microbial community stimulated by crustal fluids. Potential phosphatase activity was enhanced in phosphate-depleted layers towards the sediment-basement interface. Rates of sulfate reduction and anaerobic oxidation of methane were elevated within the lower sulfate-methane transition zone. Further investigations are focussed on isolation and characterisation of indigenous microorganisms. Molecular screening, used to determine the microbial composition of enrichment cultures from all sediment layers, revealed different phylotypes. However, as we are dealing with slowly growing prokaryotes, they need up to six months to form a colony. Therefore, the isolation and characterisation of new isolates and the preparation of publications will be finished until the end of the application period.