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

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.

This multi-disciplinary project, which links global carbon cycling to marine microbes through their biomolecular interactions, has the potential to become a landmark study in this field. Therefore, I predict that a considerable academic impact will be achieved in the fields of marine microbial ecology, molecular ecology, general microbiology, ecology, biochemistry, biogeochemistry, proteomics, metabolomics and systems biology. I will generate new knowledge on carbon cycling and potential mediation of climate change that will be of interest to the general public. Anthropogenic gas emissions and the growing concentration of CO2 in the atmosphere has become one of the main public concerns during the past decades. My findings will contribute to the knowledge on CO2 sequestration by the oceans and how these become the major sink of the growing amounts of atmospheric carbon. Therefore, my results may be of interest to Policy Makers, such as those in the Department of Energy and Climate Change, who make public policies attending to scientific results that highlight the risks of a future decrease in our quality of life, health and well-being.
The discovery of novel natural products for future biotechnological exploitation is another area of economic and societal impact of my proposal. Environmental microrganisms represent a huge reservoir of enzymatic and chemical activities that could be useful items for the green chemistry field to produce novel biotechnological products of interest. Part of my project focuses on the analysis of the secreted products of relevant marine micro-organisms which are known for being a prolific, rich and diverse source of novel biochemistry and natural products. These products (antibiotics, probiotics or bactericides) have a wide interest not only for Human health but also for other industrial activities such as fisheries or energy-producing algae plants. The potential routes for biotechnological exploitation of this resource will be investigated by setting up collaborations with industrial partners. Therefore, my project offers a potential commercialization and exploitation of the discovered natural products bringing an economical development and R&D investments from global business.
Beside improving the technical skills of the PhD students and Postdocs that will join my group, they will also have the possibility to develop their career in the setup of techniques such as: 1) co-cultures and microbial interactions; 2) analysis of secreted natural products by high-throughput techniques such as proteomics and metabolomics; and 3) study the fate of the fixed CO2 by primary producers into the Dissolved Organic Matter in the oceans, three hot-topic technology-driven issues in science today. I also intend to host an International Training Course on Environmental Biotechnology focused on applying the novel methods and techniques I will have developed during the tenancy of the Fellowship. This course would be given under the auspices of the EU-US Task Force on Biotechnology Research group and would bring together highly skilled researchers.
All the data and results generated throughout my study will be shared with the general community by making it available in public databases for it to be reused by other members of the scientific community.