Honorable Mention Winner
Sporosarcina pasteurii can perform microbially-induced calcite precipitation (MICP)—when bacteria hydrolyze urea and precipitate calcium carbonate crystals. This has potential applications in biocementation, though there are many barriers to implementation. One way to overcome these barriers is to measure cell growth and urease activity of S. pasteurii. Because urea hydrolysis increases the surrounding pH, urease activity could be measured using Stuart’s Urea Broth with the pH indicator bromothymol blue. Additionally, a standard curve was generated to quantify pH change, and cell growth of S. pasteurii was measured before and after urea hydrolysis. It was found that that higher concentrations of bacteria resulted in higher pH values and a faster pH increase, indicating higher urease activity. It was also found that cell growth declines during urea hydrolysis, and the growth media seems to influence this decline. These findings suggest that higher cell concentrations should be used in MICP applications to produce the highest urease activity and that the cell growth of S. pasteurii may not increase with urease activity
