Professor Yeala Shaked

Professor Yeala Shaked
Hebrew University & Interuniversity Institute for Marine Sciences
Abstract

Dust as a nutrient source to the N₂-fixing marine cyanobacterium Trichodesmium

Desert dust is an important source of macro- and micronutrients in remote ocean regions, but its utilization by phytoplankton is constrained by rapid sinking and low mineral solubility. In this talk, I’ll present several interdisciplinary studies showing that natural colonies of the globally significant cyanobacterium Trichodesmium overcome these constraints by efficient dust capturing and active dust dissolution.

Studying natural Trichodesmium colonies from the Northern Red Sea, we discovered several unique adaptive mechanisms for capturing and storing dust particles within the colony core that enable efficient utilization of iron (Fe) and from dust [1-11]. We showed that dust packaging within the colony core is beneficial for uptake since cell-particle proximity minimizes iron loss by diffusion [4,7], and that Trichodesmium can selectively collect and retain Fe-rich dust particles, thus optimizing Fe supply [6,9]. We discovered that Trichodesmium and its associated bacteria act together to increase the availability of dust-bound iron, where bacteria secrete Fe-binding molecules that promote dust dissolution, and Trichodesmium provides dust and optimal physical settings for dissolution and uptake [2-5, 11]. Over the last years, we expanded our research to phosphorus [9] and added new disciplines and techniques such as molecular biology, organic chemistry, high-resolution imaging, and micro-electrodes [3,7,10].

Trichodesmium is predicted to flourish in the warmer, more acidic and “dustier” future ocean. The mechanistic understanding gained by our research on its ability to utilize dust as a nutrient source will enhance our capacity for predicting the ocean’s operation modes in face of global change, and hence its impact on the atmosphere and climate.

References:

1. Rubin, M., Berman-Frank, I., and Y. Shaked. 2011. Dust- and mineral-iron utilization by the marine dinitrogen-fixer Trichodesmium. Nature Geosciences 4(8): 529–534.
2. Basu S and Y. Shaked. 2018. Mineral iron utilization by natural and cultured Trichodesmium and associated bacteria, Limnology and Oceanography 63: 2307-2320.
3. Eichner MJ, Basu S, Gledhill M, de Beer D, and Y Shaked. 2019. Hydrogen dynamics in Trichodesmium colonies and their potential role in mineral iron acquisition. Frontiers in Microbiology. 10(1565).
4. Basu S, Gledhill M, de Beer D. Matondkar S.G and Y. Shaked. 2019. Colonies of marine cyanobacteria Trichodesmium interact with associated bacteria to acquire iron from dust, Communication Biology 2(1), 1-8.
5. Gledhill M, Basu S, and Y Shaked. 2019. Metallophores associated with Trichodesmium erythraeum colonies from the Gulf of Aqaba, Metalomics. 11(9), 1547-1557.
6. Kessler N, Armoza-Zvuloni R, Basu S, Wang S, Weber PK, Stuart RK, and Y. Shaked. 2020. Selective collection of iron-rich dust particles by natural Trichodesmium colonies, The ISME Journal.  14(1):91-103.
7. Eichner MJ, Basu S, Wang S, de Beer D, and Y Shaked. 2020. Mineral iron dissolution in Trichodesmium colonies: The role of O 2 and pH microenvironments. Limnology and Oceanography. 65(6), 1149-1160.
8. Kessler N, Kraemer SM, Shaked Y and W. DC Schenkeveld. 2020. Investigation of siderophore-promoted and reductive dissolution of dust in marine microenvironments such as Trichodesmium colonies. Frontiers Marine Sciences.  
9. Wang S, Kessler N, Koedooder C, Zhang F, Shi D and Shaked Y. 2021. Colonies of the marine cyanobacterium Trichodesmium optimize dust utilization by selective collection and retention of nutrient-rich particles. iScience, 103587
10. Koedooder C, Zhang F, Wang S, Basu S, Haley ST, Tolic N, Nicora CD, Glavina del Rio T, Dyhrman ST, Gledhill M, Boiteau RM, Rubin-Blum M, and Y Shaked.  2023.  Taxonomic distribution of metabolic functions in bacteria associated with Trichodesmium consortia.  mSystems. 2023 Nov 2:e0074223.
11. Wang S, Zhang F, Koedooder C, Qafoku O, Basu S, Krisch S, Visser AN, Eichner M, Kessler N, Boiteau RM, Gledhill M, and Y. Shaked. 2024. Costs of Dust Collection by Trichodesmium: Effect on Buoyancy and Toxic Metal Release. Journal of Geophysical Research: Biogeosciences.

Yeala Shaked

Prof. Yeala Shaked is a marine biogeochemist from the Hebrew university of Jerusalem, Israel. Her laboratory is located on the magnificent Red Sea coast at the Interuniversity Institute for Marine Sciences in Eilat. She studies the interactions between organisms and their environment, emphasizing trace metal redox transformations and bioavailability to phytoplankton. She is intrigued by the fact that microorganisms, striving to acquire nutrients and protect themselves from external stressors, actively modify their chemical milieu and, in turn, influence the biogeochemical cycles of trace and major elements in the ocean. She loves the ocean and tries to connect people through science and environmental awareness.

Hosted by Professor Rene Boiteau