Molecular composition of Southern Ocean dissolved organic matter and its relation to structure and activity of prevailing microbial communities

海洋溶解有机物(DOM)所含的碳比海洋中所有生物的总和多两个数量级。尽管它对全球元素循环很重要，但我们对DOM池的源和汇、组成和动力学的了解仍然有限。DOM是异养海洋微生物的主要碳源和能源。新兴的分析技术以无与伦比的细节提供了关于DOM和微生物群落的分子信息。我们假设DOM分子组成和微生物群落密切相关，DOM中的微生物印记可以通过主要的深水团追溯到微生物最活跃的表层的主要来源。南大洋的特点是不同的水团非常接近。初级生产力的空间和时间变异性使系统在DOM组成和微生物群落结构方面具有高度的动态化。新的分析技术将为我们提供关于DOM和微生物群落的最详细的分子指纹。基于DOM分子指纹，我们将定义海洋中的DOM区域。我们假设，这些制度背后的驱动力是微生物的活性和群落组成。在全面的分子水平上，我们将把微生物过程与特定DOM化合物的循环联系起来。这将是在生物地球化学中采用系统生物学方法的第一步。

Marine dissolved organic matter (DOM) contains two orders of magnitude more carbon than all living biomass in the ocean combined. Despite its importance for global element cycles, our understanding of sources and sinks, composition and dynamics of the DOM pool is still limited. DOM is the main carbon and energy source for heterotrophic marine microorganisms. Emerging analytical techniques provide molecular information on DOM and microbial communities in unsurpassed detail. We hypothesize that DOM molecular composition and the microbial community are closely interrelated and that the microbial imprint in DOM can be traced through the major deep water masses back to its main origin in the microbially most active surface layers. The Southern Ocean is characterized by close proximity of different water masses. Spatial and temporal variability of primary productivity render the system highly dynamic with respect to DOM composition and microbial community structure. Novel analytical techniques will provide us with a most detailed molecular fingerprint on both, DOM and the microbial community. Based on DOM molecular fingerprints we will define DOM regimes in the ocean. We hypothesize that the driving force behind these regimes are microbial acitivity and community composition. On a comprehensive molecular level, we will relate microbial processes to the cycling of specific DOM compounds. This will be a first step towards a systems biology approach in biogeochemistry.