Urease purification from indigenous soil bacteria and accumulation of CaCO3 crystals

Abstract

Recently, microbiologically induced calcite precipitation has been evaulated as an effective and eco friendly alternative a repair technique in plugging of microcracks and pores in concrete for building trade. Activity of urease enzyme synthesized by micoorganisms has been induced to the precipitation of CaCO₃ crystals. Urease activity and urease-induced calcium carbonate mineralization of indigenous soil bacteria (Bacillus spp.) isolated from Kilis, Turkey were investigated in this study. Total and spesific urease activity of crude 19B intracellular enzyme sample were calculated as 0.67±0.003 EU/mL/min and 0.63±0.011 µmol/min/mg, respectively. Three protein bands (50.61, 34.03 and 30.36 kDa) indicating the subunits of urease were detected by SDS-PAGE. Microbial calcium carbonate precipitation was analyzed by SEM/EDX. Rhombohedral calcite crystals were clearly observed in SEM images. And element composition of the precipitate was revealed to mostly comprise of calcium, carbon and oxygen. All these results stated that 19B strain may be evaultaed for engineering applications such as remediation of concrete cracks and enhancing compressive strength of cement.