Acclimation of a low iron adapted Ostreococcus strain to iron limitation through cell biomass lowering

Abstract

Iron is an essential micronutrient involved in many biological processes and is often limiting for primary production in large regions of the World Ocean. Metagenomic and physiological studies have identified clades or ecotypes of marine phytoplankton that are specialized in iron depleted ecological niches. Although less studied, eukaryotic picophytoplankton does contribute significantly to primary production and carbon transfer to higher trophic levels. In particular, metagenomic studies of the green picoalga Ostreococcus have revealed the occurrence of two main clades distributed along coast-offshore gradients, suggesting niche partitioning in different nutrient regimes. Here, we present a study of the response to iron limitation of four Ostreococcus strains isolated from contrasted environments. Whereas the strains isolated in nutrient-rich waters showed high iron requirements, the oceanic strains could cope with lower iron concentrations. The RCC802 strain, in particular, was able to maintain high growth rate at low iron levels. Together physiological and transcriptomic data indicate that the competitiveness of RCC802 under iron limitation is related to a lowering of iron needs though a reduction of the photosynthetic machinery and of protein content, rather than to cell size reduction. Our results overall suggest that iron is one of the factors driving the differentiation of physiologically specialized Ostreococcus strains in the ocean.

Limitation by Fe, Zn, Co, and B12 Results in Similar Physiological Responses in Two Antarctic Phytoplankton Species

“…As previously observed for P. antarctica (Koch et al, 2019;Trimborn et al, 2019a) and other phytoplankton species (Allen et al, 2008;Botebol et al, 2017;Blanco-Ameijeiras et al, 2018), Fe limitation significantly affects cellular physiology. Typically Fe-limited cells grow more slowly, are often smaller, alter their photophysiology and have reduced particulate organic carbon (POC) quotas.…”

Picoeukaryotes of the Micromonas genus: sentinels of a warming ocean

“…In the end, temperature is a sufficient parameter to describe the latitudinal segregation of Micromonas between Tara Oceans stations. The current typology of Tara Oceans (they mainly are open ocean areas), does not allow to fully assess a possible effect of nutrients [68].…”

Stable wastewater treatment with Neochloris oleoabundans in a tubular photobioreactor

“…By taking into consideration the amount of iron which was added during the batch and the 42 μmol added with the inoculum, it was calculated that the iron content in the wastewater was at least 8.3 μM (400-42 μmol per 43 L). This is not a low concentration for algal growth, as many marine algae can be cultivated at 0.3 μmol L −1 Fe (Botebol et al 2017). However, the observation that iron deficiency was detected immediately upon starting continuous growth indicates that the algae had consumed virtually all iron of the wastewater during the batch phase, and the continuous additions of wastewater did not bring enough iron to the medium to support the continuous phase.…”