Urease purification from indigenous soil bacteria and accumulation of CaCO3 crystals

Recently, microbiologically induced calcite precipitation has been evaluated as an effective and eco friendly alternative to a repair technique in plugging of microcracks and pores in concrete for building trade. Enzymatic activity of urease synthesized by microorganisms has been induced for precipitation of CaCO3 crystals. Urease activity and urease-induced calcium carbonate mineralization of indigenous soil bacteria (Bacillus spp.) isolated from Kilis, Turkey were studied. Total and specific urease activity of crude 19B intracellular enzyme sample were calculated as 0.67 +/- 0.003 EU/mL/min and 0.63 +/- 0.011 mu mol/min/mg, respectively. Three protein bands (60.48, 23.27 and 20.17 kDa) indicating subunits of urease were detected by SDS-PAGE. Microbial calcium carbonate precipitation was analyzed by Scanning Electron Microscopy/Energy Dispersive X-Ray Analysis. Rhombohedral calcite crystals were clearly observed in SEM images. Element composition of precipitate was revealed to mostly comprise of calcium, carbon and oxygen. Results indicated that 19B strain may be evaluated for engineering applications such as remediation of concrete cracks and enhancing compressive strength of cement.