The Isolation and Characterization of <i>Glutamicibacter</i> DC1 to Induce Carbonate Precipitation of Some Heavy Metals at Low-Temperature

Abstract

The psychrotolerant bacteria able to induce carbonate precipitation of heavy metals at low temperatures play an essential role in the remediation of heavy metal contaminated soil in cold regions. In this study, a psychrotolerant bacterial strain DC1 with carbonate mineralization potential, identified as Glutamicibacter sp., was isolated from tailing soil. The optimal temperatures and pH range for the growth of strain DC1 were 10-30ºC and 6-8, respectively. Besides, strain DC1 showed a high degree of resistance to various metals (Pb>Cu>Ni>Cd). Furthermore, strain DC1 produced a large amount of urease (266.91 U/mL), which induced the fermentation suspension's pH (pH 9.5 at 10ºC). Moreover, the fermentation suspension of strain DC1 could generate carbonate precipitates of various metals (Pb, Cd, Ni, and Cu) to remove them from the solutions. Based on the analyses of XRD, SEM, and EDS, the carbonate precipitates of Pb and Cd have been identified as PbCO 3 and CdCO 3 mineral crystals, respectively. In contrast, no mineral crystals of Ni and Cu existed. Furthermore, the carbonate minerals of Cd and Pb with regular crystal improved resistance to dilute acid. Thus, this study showed that strain DC1 without acid production could induce carbonate precipitates of Pb, Cd, Cu, and Ni at lowtemperature.