Iron and phosphorus deprivation induce sociality in the marine bloom-forming cyanobacterium Trichodesmium

Yael Tzubari, Liel Magnezi, Avraham Be'Er, Ilana Berman-Frank

Research output: Contribution to journalArticlepeer-review


Trichodesmium spp. are diazotrophic cyanobacteria that exist as single filaments (trichomes) and as macroscopic colonies of varying shapes formed by aggregating trichomes. The causes and dynamics of colony formation and disassociation are not yet elucidated. we demonstrate that limited availability of dissolved phosphorus (P) or iron (Fe) stimulated trichome mobility and induced colony formation in Trichodesmium erythraeum IMS101 cultures. The specific nutrient limitation differentially affected the rate of colony formation and morphology of the colonies. Fe starvation promoted rapid colony formation (10-48 h from depletion) while 5-7 days were required for colonies to form in P-depleted cultures. Video analyses confirmed that the probability of trichomes to cluster increased from 12 to 35% when transferred from nutrient replete to Fe-depleted conditions. Moreover, the probability for Fe-depleted aggregates to remain colonial increased to 50% from only 10% in nutrient replete cultures. These colonies were also characterized by stronger attachment forces between the trichomes. Enrichment of nutrient-depleted cultures with the limited nutrient-stimulated colony dissociation into single trichomes. We postulate that limited P and Fe availability enhance colony formation of Trichodesmium and primarily control the abundance and distribution of its different morphologies in the nutrient-limited surface ocean.

Original languageEnglish
Pages (from-to)1682-1693
Number of pages12
JournalISME Journal
Issue number7
StatePublished - 1 Jun 2018
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements We thank Dr. Avi Jacob of the light microscopy unit and Dr. Yaakov Langsam of the E-SEM unit at Bar Ilan University for their generous help and support in preparation and analyses. AB is thankful for partial support from the Israel Science Foundation Grant No. 373/16, and the Roy J. Zuckerberg Career Development Chair for Water Research for partial support. Funding for IBF was via the Schulich Ocean Studies Centre Initiative at Dalhousie University, and a collaborative grant from MOST Israel and the High Council for Science and Technology (HCST), France. This work is in partial fulfillment of the requirements for a PhD thesis for YT and an MSc thesis for LM at Bar Ilan University. Support for YT was provided with a student fellowship from the Mediterranean Sea Research Center of Israel (MERCI).

Publisher Copyright:
© 2018 International Society for Microbial Ecology.

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics


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