Abstract:

In order to study whether Bacillus mucilaginosus can promote the formation of calcium carbonate or not under certain
conditions, this research adopted two commonly used basic media of Bacillus mucilaginosus. The one is the nitrogen medium, and
the other  is  the nitrogen-free medium. The apatite mineral was  the sole source of calcium, and  the B. mucilaginosus was grown
in different media  to synthesis calcium carbonate. Scanning electron microscopy  (SEM), energy dispersive spectrometer  (EDS)
quantitative analysis, and X-ray diffraction  (XRD) analysis were used  to observe and study  the crystal structure and chemical
composition of  the  formed calcium carbonate. The  results showed  that B. mucilaginosus can accelerate  formation of calcium
carbonate. The crystals, calcium carbonate particles  formed  in  the nitrogen medium containing apatite powders were more  than
those in the nitrogen-free medium containing apatite powders. Meanwhile, the columnar calcium carbonate crystals were observed
in  the nitrogen medium containing apatite powders. The mechanism  for B. mucilaginosus  to promote  formation of calcium
carbonate might be  the secretion of carbonic anhydrase  (CA) and dissolved CO2  in  the process of apatite weathering and strong
absorption features of bacteria.

Key words:  Bacillus mucilaginosus； calcium carbonate；biomineralization；induced mineralization