[Curvibacter sp. strain HJ-1 induced the formation of aragonite under the condition of low Mg/Ca ratio].

Objective: To study the effects of bacteria on the species and morphology of carbonate minerals.

Methods: We conducted a series of cultural experiments in the medium with initial Mg/Ca ratio of 2 but without carbonate ion using Curvibacter sp. strain HJ-1 for 50 days. During the cultivation, bacterial density, precipitate quantities, calcium and magnesium concentration were determined. The morphologies of precipitated carbonates were observed using scanning electron microscopy, and mineral species of carbonate were determined by X-ray diffraction.

Results: Strain HJ-1 could induce the precipitation of carbonate minerals, the quality of carbonate gradually increased with the incubation time. XRD patterns showed that the mineral precipitates consisted of high-Mg calcite and aragonite. The percentage of aragonite in the precipitates was up to 86%. The morphology of carbonate minerals was multiform, including rod-shaped, dumbbell-shaped, spherical, tabular, as well as irregular and flake.

Conclusion: The formation of aragonite under the condition of low Mg/Ca ratio has a close correlation with extracellular polysaccharide secreted by Curvibacter sp. strain HJ-1.