Postdoc: Neha Mehta (director: Karim Benzerara)

Collaboration: Puri Lopez-Garcia and David Moreira, DEEM Team at Orsay, France

Funding: ERC Calcyan, ANR Harley

         Recently, several cyanobacterial species have been reported to form intracellular amorphous calcium carbonate (ACC) and/or polyphosphates (PolyP) inclusions. These cyanobacteria were found in diverse environments and accumulate high concentrations of AEE (Ca, Ba and Sr) from solutions undersaturated with respect to AEE.  Ongoing work from our group discovered that certain species of ACC-forming cyanobacteria are able to grow in solutions where Ca has been fully replaced by Sr or Ba (Figure1). Indeed, we succeeded in adapting two ACC‐forming cyanobacteria strains to grow in Ca-free solutions, containing either Sr or Ba only. This adaptation was surprising because Ca is widely recognized as an essential biological element for all eukaryotes and prokaryotes, playing a vital role in several biological processes. In this project, we will assess the impact of Ca vs Sr vs Ba on the fitness of the adapted strains. This will be accomplished by a combination of physiological experiments, genomics, and electron microscopy. The results will help us to understand how these cyanobacteria maintain a state of unusual AEE homeostasis across a wide variety of environments for the past millions of years.

@ Neha Mehta