IRONCOMM · Investigating the role of bacteria-produced siderophores in satisfying diatom Fe requirements.
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-07-01 → 2019-06-30
- EU contribution
- €173,076
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Investigating the role of bacteria-produced siderophores in satisfying diatom Fe requirements.
The greatest impact of climate change due to rising atmospheric CO2 has been and will continue to be exerted on ocean biomes. Ocean warming dominates the increase in energy stored in the climate system, whilst uptake of CO2 drives the decrease in pH of seawater. An ensuing change will be to the speciation and solubility of divalent metals. The primary aim of IRONCOMM is to shed light on how marine microbial communities will respond to changing pools of iron in a progressively acidifying and warming Ocean. The focus is on diatoms in particular, which are ubiquitous in ocean waters and are responsible for an estimated 20% of the total primary production on Earth. They are key players in microbial marine ecosystems, which means that knowledge gained in diatom model systems is immediately globally scalable. The research of IRONCOMM is concerned with Fe in particular, since this micronutrient has been shown to play a regulating role in the growth dynamics of marine phytoplankton. There were three main objectives to the project: 1. To identify whether diatoms are able to uptake and use siderophores, which are organic chelators of iron. It is unclear whether siderophore bound iron is bioavailable to diatoms. 2. To develop laboratory co-culture systems for exploring the hypothesis for mutualism between siderophore-producing bacteria and diatoms. 3. To assess the extent of siderophore uptake by photosynthetic eukaryotes and possible implicated interactions with bacterioplankton in the global ocean based on metatranscriptome data catalogued as part of the Tara Oceans project. IRONCOMM takes an interdisciplinary approach that marries molecular studies of laboratory model systems to global scale analyses of environmentally-derived metatranscriptomic data. Conclusions: We were successful in meeting all three of the objectives of IRONCOMM. We experimentally verified that diatoms are capable of siderophore uptake and use. In published results, we showed that a) diatoms have a preference for the type of siderophore they uptake, b) the uptake mechanism relies on endocytosis (a eukaryote-specific adaptation), c) we identified some of the molecular components involved in the process, notably the Iron Starvation Induced Protein 1 (ISIP1), which is necessary for this function. We conducted phylogenetic analyses and showed that ISIP1 is a diatom-specific protein, suggesting that this may be a diatom adaptation, which has led to the dominance of diatoms in present day oceans. Further, to meet objective 3 we mined the Tara Oceans dataset and were able to show that ISIP1 is ubiquitously expressed in ocean waters. We proposed the use of ISIP1 as a global biomarker for siderophore uptake and use – an important component of global ocean models used in climate change research. Finally, we met our second objective, by isolating bacteria associated with diatoms and identifying siderophore producers. In ongoing work we are investigating the partnerships between siderophore producers and diatoms.
Data: CORDIS, © European Union
Project objective
The greatest impact of climate change will be exerted on ocean biomes. In order to mitigate for its effects it is paramount to understand the dynamics of phytoplankton communities within, which are responsible for marine carbon fixation (50% of the of the primary production on Earth). Our current understanding of phytoplankton dynamics is limited – particularly when linking a molecular level understanding of metabolic processes with ecology. In the proposed work I will investigate the hypothesis that diatoms, which are ubiquitous phytoplankton species across all marine habitats interact with bacteria to acquire bioavailable iron from siderophores produced by the latter. My investigations will address this aim across all scales of biological organization. I will capitalize on preliminary investigations at the host laboratory that have begun to unravel the molecular pathways associated in siderophore acquisition in diatom species. My work will be novel in terms of characterizing the molecular mechanism by which siderophores are transported into and distributed to where required within diatom cells. Further, I will explore the hypothesis that siderophore acquisition is a result of mutualism between bacteria and diatoms. The results will bear important eco-evolutionary consequences to our understanding of microbial communities. Finally, on a global scale, I will quantify the relevance of my findings by mining of metatranscriptomic data collected in global transects of the ocean (specifically during the Tara Oceans expedition). Through this fellowship I will develop a range of new technical skills including novel molecular techniques and bioinformatics, as well as transferable competencies (e.g. using French at work). The fellowship will provide me with an opportunity to return to Europe (from the USA), expanding my academic network of collaborators and putting me in a prime position for applying for faculty positions as a next step in my academic career.
Original text from CORDIS.
Participants
- CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE CNRS · ParisCoordinatorFrance
Links
Data: CORDIS, © European Union