Newly-discovered interactions between bacteriophages and the process of calcium carbonate precipitation

Although it has been suggested that viruses may induce precipitation of carbonate, the exact mechanisms involved and the roles they might play in the nucleation of carbonates are still unknown. Experimental evidence is reported here demonstrating that bacteriophages are an important factor in calcium carbonate formation. Short-term experiments were designed to induce viral-mediated mineral precipitation at different fluid compositions. The precipitates obtained, analysed with fluorescence and electron microscopes and X-Ray diffraction, and evaluated by statistics, clearly show that bacteriophages strongly affect the process of carbonate precipitation. We demonstrate that as a result of the coalescence of the phages, the carbonate precipitates form large aggregates consisting of spheroids. The spheroids are constructed of angular nanoparticles resembling viral-like particles. In control experiments spheroids were also observed; however, they consist of irregular nanoparticles and additionally they do not form large aggregates. We also demonstrate that bacteriophages strongly influence the mineral composition of the precipitates, with vaterite being the dominant form, and they likely control vaterite stability.