Testing the Capacity of Staphylococcus equorum for Calcium and Copper Removal through MICP Process

This research focused on the evaluation of the potential use of a soil-isolated bacteria, identified as Staphylococcus equorum, for microbial-induced calcite precipitation (MICP) and copper removal. Isolated bacteria were characterized considering growth rate, urease activity, calcium carbonate precipitation, copper tolerance as minimum inhibitory concentration (MIC) and copper precipitation. Results were compared with Sporosarcina pasteurii, which is considered a model bacteria strain for MICP processes. The results indicated that the S. equorum strain had lower urease activity, calcium removal capacity and copper tolerance than the S. pasteurii strain. However, the culture conditions tested in this study did not consider the halophilic feature of the S. equorum, which could make it a promising bacterial strain to be applied in process water from mining operations when seawater is used as process water. On the other hand, copper removal was insufficient when applying any of the bacteria strains evaluated, most likely due to the formation of a copper-ammonia complex. Thus, the implementation of S. equorum for copper removal needs to be further studied, considering the optimization of culture conditions, which may promote better performance when considering calcium, copper or other metals precipitation.

Automated summary

The study found that compared to Sporosarcina pasteurii, the Staphylococcus equorum strain showed lower activity in microbial-induced calcite precipitation and copper removal. However, the halophilic feature of S. equorum was not considered, making it a promising bacterial strain for application in process water when seawater is used. Copper removal was insufficient, likely due to the formation of a copper-ammonia complex. Further research on the optimization of culture conditions for S. equorum in copper removal is needed for better performance in calcium, copper, or other metals precipitation.