Structural study of bacterial Amorphous Calcium Carbonate

Biogenic amorphous calcium carbonate (ACC) was first documented in eukaryotes, where ACC acts as a precursor phase for the formation of crystalline carbonate minerals. Recent studies have shown that environmentally and taxonomically diverse prokaryotes and one microalga are capable of forming intracellular ACC . Unlike pure abiogenic ACC, which rapidly transforms to crystalline polymorphs, ACC found in prokaryotes remains stabilized intracellularly with no obvious spontaneous transformation to crystalline phases. Numerous organic and inorganic additives have been shown to perform this role, but the mechanisms yet remain elusive. In my postdoctoral research, I am interested in understanding the stability, reactivity, and formation of intracellular ACC formed by bacteria, through the lens of high-resolution spectroscopy techniques. To that end, I have developed methodological tools to study bacterial ACC in-situ using (1) Solid-state NMR spectroscopy (ssNMR) that enables to explore of the local molecular environment surrounding the organic-mineral interface; (2) Extended X-ray absorption fine structure (EXAFS) spectroscopy that is effective in probing short-range order of disorderly phases such as ACC and thus offers clues about how local structure drives the stability of ACC. An example of some highlights from the ongoing work are shown below: