Eco-interactomics: From microbial interactions to the fate of dissolved organic matter in the oceans.

随着越来越多的证据表明这与气候变化有关，温室气体排放和大气中二氧化碳(CO2)浓度的增加变得更加重要。科学面临的一大问题是，能够从大气中去除二氧化碳的植物、藻类和其他生物将如何应对不断增加的浓度，以及它们是否能够抵消部分增加的二氧化碳。大气中二氧化碳周转量的一半来自陆地植被，另一半发生在海洋。在陆地上，植物对二氧化碳的吸收与它们死亡和分解时释放的二氧化碳相平衡。在海洋中，通过光合作用从空气中去除的二氧化碳比通过腐烂作用释放的更多。这意味着海洋可以起到碳储存的作用，其中一个主要原因是海洋中的微生物产生了有机物，这些有机物随后沉入更深的水域，在那里可以保留数十年甚至数百年。了解海洋微生物食物网络以及这种二氧化碳储存是如何发生的至关重要，因为它将使我们能够预测海洋将如何应对大气中人造二氧化碳浓度的增加，以及这可能如何影响气候变化。在海洋中，尽管光合作用微生物的丰度相对较低(不到总生物体的10%)，但它们是维持整个生态系统的主要食物和能源来源。这些生物将大量有机物释放到水中，然后被水中存在的其他微生物分解并用作食物来源。这些降解者将利用这些有机物的大部分，将必要的元素循环利用到新的生长中。然而，这些有机物质的一部分将被转化为较难降解的化合物，这些化合物将沉没并保留在海洋深处。这项研究将侧重于有机物通过海洋食物网的途径，从初级生产者到最终降解者，直到它被转化为这些较难降解的化合物，以确定碳在食物网中的流动，并确定谁降解了什么，以什么顺序降解。在海洋等稳定的环境中，为了更有效地利用稀缺资源，进化使自由生活的有机体失去了重要功能。这导致了一个相互依赖的有机体群落。因此，光合作用的生物体依赖于降解的生物体，降解的生物体以它们产生的有机化合物为食，反之亦然。这个项目将研究这种相互作用是如何在分子水平上发生的，并将研究微生物食物网内的关系如何依赖于天然产品的分泌。海洋中的微生物分泌大量的化合物，以改变或影响它们的群落和环境。由这些秘密产品引起的相互作用可以是友好的，也可以是敌对的。然而，这个庞大的秘密化合物池的真正功能和目标在很大程度上是未知的。了解分泌的元素将使我们更好地了解海洋微生物生态系统内发生的过程和相互作用，鉴于其在推动海洋食物网方面的作用，我们仍然知之甚少。因此，我的项目的主要目标之一是获得关于初级生产者和降解者如何通过他们的秘密产品相互作用的新见解。对这些分泌产物的研究将发现大量不仅对人类健康有兴趣的新天然产品(如抗生素、益生菌或杀菌剂)，而且还对其他工业活动，如渔业或生产能源的藻类植物有兴趣。这个项目将提供一个非常必要的理解，了解微生物群落如何在海洋中相互作用，以及这如何影响海洋中大气碳的保留，并作为大气中二氧化碳增加的缓冲。

Greenhouse gas emissions and the growing concentration of carbon dioxide (CO2) in the atmosphere has become more important as evidence increasingly links this to climate change. One of the big questions for science is how plants, algae and other organisms which are able to remove this CO2 from the atmosphere will respond to increasing concentrations and whether they will be able to offset some of this increase.Half of the atmospheric turnover of CO2 comes from land based vegetation and the other half takes place in the oceans. On land uptake of CO2 by plants is balanced by the CO2 released when they die and decompose. In the oceans more CO2 is removed from the air by photosynthesis than is released by decay. This means the oceans can act as carbon stores and one of the main reasons for this is the production of organic matter by the microorganisms in the oceans which subsequently sinks into deeper waters where it can be retained for decades or even centuries. Understanding the marine microbial food web and how this CO2 storage occurs is vitally important as it will allow us to make predictions about how the oceans will react to increasing concentrations of man-made CO2 in the atmosphere and how this could influence climate change. In the oceans, photosynthetic microorganisms, despite their relatively low abundance (under 10% of total organisms) are the main source of food and energy to sustain the whole ecosystem. These organisms release large amounts of organic matter into the water that can then be broken down and used as a food source by other microorganisms present in the water. These degraders will use most of this organic matter, recycling essential elements into new growth. Nevertheless, part of this organic matter will be converted into less degradable compounds that will sink and be retained in the ocean depths. This study will focus on the pathway followed by organic matter through the marine food web, from primary producers to final degraders, until it is converted into these less-degradable compounds, to determine the flow of carbon through the food web and identify who degrades what and in what order. In stable environments, such as oceans, evolution has pushed free-living organisms to lose vital functions in order to use the scarce resources more effectively. This has resulted in a community of organisms dependent on each other. Thus organisms which photosynthesise are dependent on the degrading organisms which feed off the organic compounds they produce and vice versa. This project will look at how this interaction is occurring at the molecular level and will examine how relations within the microbial food web rely on the secretion of natural products. Microorganisms in the ocean secrete an enormous range of compounds in order to modify or exert an influence on their community and environment. The interactions caused by these secreted products can be friendly or hostile. However, the real function and target of the enormous pool of secreted compounds is largely unknown. Understanding the secreted elements will give a greater understanding of the processes and interactions occurring within the marine microbial ecosystem, something which, given its role in driving the marine food web, we still know very little about. Therefore, one of the major objectives of my project is to gain new insights into how primary producers & degraders interact through their secreted products. The study of these secreted products will identify a large array of novel natural products with interest not only for human health (such as antibiotics, probiotics or bactericides) but also for other industrial activities such as fisheries or energy-producing algae plants.This project will provide a much needed understanding of how microbial communities interact in the oceans and how this can influence the retention of atmospheric carbon in the seas and act as a buffer against increasing CO2 in the atmosphere.