High concentration heavy metal removal by indigenous ureolytic bacteria: A comparative study with Sporosarcina pasteurii for Zn and Cd bioprecipitation

Heavy metal pollution from industrial activities threatens aquatic ecosystems and human health. While microbially induced carbonate precipitation (MICP) offers a promising bioremediation strategy, most studies rely on laboratory-adapted strains, such as Sporosarcina pasteurii, and provide limited comparisons with indigenous microbes under identical stress conditions. We hypothesized that an indigenous ureolytic bacterium, pre-adapted to metal-contaminated environments, would outperform S. pasteurii under suboptimal temperatures and high cadmium (Cd) and zinc (Zn) concentrations, a gap unaddressed in prior MICP literature. Here, we compare the carbonate precipitation efficiency of Comamonas sp. HMZC (B11), isolated from a polluted river catchment, with S. pasteurii at 15°C and 30°C using 6 mM and 8 mM Cd or Zn over 96 hours. Strain B11 achieved >90% removal of both metals at 30°C, comparable to or slightly better than S. pasteuri, and maintained 70–85% efficiency at 15°C, with a statistically significant advantage in Zn removal under cold stress. SEM-EDS and XRD confirmed well-crystallized CdCO 3 and ZnCO 3 precipitates, with B11 yielding higher crystallinity. These results support the use of indigenous strains, such as B11, for biostimulation-based, site-specific remediation of heavy-metal-contaminated waters. • Comamonas sp. HMZC achieves >94% Cd/Zn removal at 6 mM, 30°C; 96.2% Cd at 8 mM. • Comamonas sp. HMZC shows novel MICP potential vs. S. pasteurii. • B11 removes 70-85% Cd/Zn at 15°C, often outperforms S. pasteurii. • SEM-EDS/XRD confirms stable CdCO 3 /ZnCO 3 ; Comamonas sp. HMZC yields high crystallinity. • Comamonas sp. HMZC supports biostimulation for sustainable heavy metal bioremediation.