Calcium carbonate precipitation by urease and carbonic anhydrase positive bacteria

In present study, CaCO3 precipitation was examined in two ureolytic bacteria. Bacillus aerius U2 and Sporosarcina pasteurii ATCC 6453 were used as test organisms. The determination of urease and carbonic anhydrase enzyme activities were also determined. For further confirmation of the calcium carbonate mineral type produced by bacteria, XRD, SEM and EDX analysis were done. Strain U2 produced calcite and vaterite. In S. pasteurii ATCC 6453, only vaterite was found. The enzyme activity studies showed that both urease and carbonic anhydrase activities was 2-50-fold higher in S. pasteurii ATCC 6453 than B. aerius U2. Although, S. pasteurii ATCC 6453 was better option for microbial calcium carbonate precipitation (MCP) at higher temperature, by B. aerius U2 at lower temperature (<30 degrees C) is made possible to employ in the most geotechnical applications.