Biomineralization processes and cyanobacteria:
The process of calcification in cyanobacteria has long been considered as extracellular and non-biologically controlled. However, this paradigm was recently challenged by discovery of environmentally and taxonomical diverse cyanobacteria forming intracellular amorphous calcium carbonate (ACC). My current work focuses on developing a fundamental understanding of the intracellular ACC formation by cyanobacteria and its environmental relevance. Below are some highlights of this work:
Role of Ca, Sr and Ba in cyanobacteria forming intracellular ACC
In my current postdoctoral work, I discovered that certain species of ACC-forming cyanobacteria are able to grow in solutions where Ca has been fully replaced by Sr or Ba. Below is a STEM-EDX image of Synechococcus 6312 adapted to grow on Ba and in absence of Ca and forms intracellular amorphous Ba carbonate inclusions.
This adaptation was surprising because Ca is widely recognized as an essential biological element for all prokaryotes, playing a vital role in several biological processes. In this project, I aim to understand the biochemical mechanisms underlying this unique adaptation, assess the impact of Ca vs Sr vs Ba on the fitness of the adapted strains and eventually understand how these cyanobacteria maintain a state of unusual alkaline earth element homeostasis.
Rapid detection of ACC forming cyanobacteria in the environment
While the formation of intracellular amorphous calcium carbonate (ACC) by living organisms is widespread, its detection in cyanobacteria remains difficult owing to its susceptibility to transform or dissolve upon sample preparation. Because of these challenges, a large number of ACC-forming cyanobacteria may have been undetected and their abundance in the natural environment is possibly underestimated. This study identifies diagnostic spectral markers of ACC-forming prokaryotes that facilitate their detection in the environment and facilitate rapid detection of ACC forming cyanobacteria in the environment, a prerequisite to shed light on the role of ACC forming cyanobacteria in the geochemical cycle of Ca in the environment.