Short communicationWhole-cell evaluation of urease activity of Pararhodobacter sp. isolated from peripheral beachrock

- Pararhodobacter sp. produced urease in association with cell growth.
- The urease showed extremely high stability during cultivation for 15 days.
- The urease was not secreted and detected in a soluble fraction of cell lysate.

Pararhodobacter sp. SO1 is a urease-producing bacterium and can be used for microbial induced calcium carbonate precipitation (MICP). In the present study, microbial cells are directly used for the analysis of urease activity without extraction or purification of urease. The whole-cell evaluation of the bacteria provides important and comprehensive information on urease activity because the bacterial cells are directly used in biomineralization process. The urease activity of Pararhodobacter sp. increased with cell growth during cultivation and the bacteria maintained its enzyme activity even after 15-days culture. High urease activity was obtained at relatively high temperature around 60 °C and neutral pH around 8. It is revealed that urease was not secreted in culture medium but would accumulate in/on the cell, and resuspended cells obviously showed urease activity. Meanwhile, the enzyme activity was detected in a soluble fraction of cell lysate. Furthermore, clear band based on urease activity was observed in soluble fraction of cell lysate in native PAGE analysis followed by activity staining. These findings will contribute to the efficient biocementation using this ureolytic bacteria.

Urease activity of Pararhodobacter sp. was evaluated in a whole cell system, revealing that the enzyme showed extremely high stability during cultivation for 15 days. The enzyme was not secreted to the medium and was detected in a soluble fraction of cell lysate.145