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The role of trace metals in controlling structure and function of microbial communities in contemporary oceans
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Selective collection of iron-rich dust particles by natural Trichodesmium colonies (Invited)
Tuesday 8th @ 0930-0950, Conference Room 1
Yeala Shaked* , Hebrew University of Jerusalem and Interuniversity Inst. for Marine Sciences, Israel
Rachel Zvoluni-Armoza, Hebrew University of Jerusalem and Interuniversity Inst. for Marine Sciences, Israel
Subjahit Basu, Hebrew University of Jerusalem and Interuniversity Inst. for Marine Sciences, Israel
Siyuan Wang, Hebrew University of Jerusalem and Interuniversity Inst. for Marine Sciences, Israel
Peter Weber, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA, USA
Rhona Stuart, Physical and Life Sciences, Lawrence Livermore National Laboratory, Livermore, CA, USA
Nivi Kessler, Hebrew University of Jerusalem and Interuniversity Inst. for Marine Sciences, Israel
Presenter Email: yeala.shaked@mail.huji.ac.il |
| Dust is considered an important source of iron (Fe) to vast region of the oceans in which Fe scarcity limits phytoplankton growth. Trichodesmium, a globally important, N2-fixing cyanobacterium, establishes large surface blooms in ocean regions that receive high dust fluxes. Trichodesmium holds special adaptations for utilizing dust as a source for Fe, including efficient dust capturing within their intricate colony morphology, dust shuffling to the colony core, and active dust dissolution. In this study we explored various components of the interaction between natural and cultured Trichodesmium and dust with an emphasis on the role of Fe in these interactions.
SEM and NanoSIMS images of natural Trichodesmium colonies from the Gulf of Aqaba revealed dust and Fe-rich particles in their core, possibly hinting at selective collection of Fe-rich particles. Trichodesmium culture, IMS101 did not form any stable interactions with dust when grown as single filaments, regardless of its growth phase or Fe status. However, when single filaments were induced to form colonies under Fe limitation, the colonies readily adsorbed dust, suggesting that IMS101 can regulate it adhesiveness towards dust. Dust collection by natural colonies also seems to be regulated as the adhesiveness of the colonies towards dust gradually shifted over an entire bloom season.
In depth characterization of the interaction between particles and over 600 natural colonies during 24 hr incubations revealed surprisingly complex behavior with regards to particle collection, translocation and retention within the colony core. Defining individual behavioral parameters, we assigned each with a scoring scheme, and probed for differences in the colony behavior with respect to Fe-free and Fe-rich particles. Strong preference for Fe-rich particles over Fe-free particles was observed in all behavioral parameters for both individual colonies and the whole population, throughout the whole season. The preference for Fe-rich particles was evident even during initial particle collection (15 min after addition) and it increased further as the interaction progressed and the colonies kept on collecting and shuffling Fe-rich particles to their center. Fe-free particles were not only collected to a smaller degree, but were also actively discarded from some of the colonies that initially collected them. These intriguing findings hint at yet unexplored, highly sophisticated particle collection systems in natural Trichodesmium involving chemical sensing of Fe and complex behavioral patterns; and as such contribute to Trichodesmium's efficient utilization of dust as a source for Fe.
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