A novel constructed carbonate-mineralized functional bacterial consortium for high-efficiency cadmium biomineralization

Highlights: • An urease-producing consortium (UPC) for Cd mineralization was constructed. • Three functional genera increased in acclimation process and compose the consortium. • The consortium exhibited adaptability to a wide range of environmental conditions. • 92.87 % Cd was mineralized at 8 h to a carbonate bound form by the consortium. • Cd removal ability and microbial structure was stable after multiple transfers. A stable, urease-producing consortium (UPC) was constructed for high-efficiency cadmium (Cd) ion mineralization via a short-term and efficient acclimation process (five acclimation transfers). 16S rRNA gene high-throughput sequencing and quantitative polymerase chain reaction (qPCR) analyses of the urease subunit C (ureC) gene suggested that the three functional genera, all belonging to the phylum Firmicutes, rapidly increased during the process and finally composed the UPC (70.22–75.41 % of Sporosarcina, 13.83–20.66 % of norank_fBacillaceae, and 5.91–13.69 % of unclassified_fBacillaceae). The UPC exhibited good adaptability to a wide range of environmental conditions (a pH range of 4.0–11.0, temperature range of 10−45 °C, and Cd concentration range of 0−200 mg L⁻¹). After 8 h of incubation, 92.87 % of Cd at an initial concentration of 100 mg L⁻¹ was mineralized by UPC, exhibiting a great improvement as compared to the first acclimated consortium (C-1). Furthermore, although the acclimated consortium had been successively transferred 21 times, the Cd biomineralization efficiency remained stable, and this was consistent with the observed stable microbial community structure. X-ray diffraction (XRD) spectra revealed that Cd was mineralized in a (Ca0.67, Cd0.33)CO₃ phase. This research obtained a promising microbial resource for the biomineralization of Cd or other hazardous heavy metal contaminants.