Isolation and Characterization of Urease Utilizing Bacteria to Produce Biocement

Abstract

Cement is a material which maintains durability of building structure and conservation of cultural heritage. Although hundreds and thousands of successful concrete and buildings are annually constructed worldwide, there are large number of concrete structures (including historical monuments), that deteriorates or become unsafe in loading. Hence ,in order to overcome the short comings of conventional sealing agent, materials with self healing capability can be used effectively. Use of urease producing microbes addresses these problems effectively as these continue to survive and grow within the concrete structure after the initial use. Urease help in mineralization of Calcium carbonate, by hydrolyzing urea present in the environment. It releases carbon dioxide from urease activity, bacteria are able to use urea as sole nitrogen source and produce ammonia which increases the pH in the proximal environment causing Ca 2+ and Co 3+ to precipitate as Ca 2 Co 3 . These unique proprieties make it particularly suitable for many applications in civil engineering (concretestructures ,plasters, mortars, prefabricated elements, refractory elements, bricks, and stones).The Microbes isolated from the sewage samples is tested for Urea hydrolyzing and tolerance capacities. Urease positive bacteria is used to produce Biocement in-vitro by incubating it for one week then the precipitated biomass is filtered and air dried, the biomass is checked for its porosity using Scanning Electron Microscope comparing to the ordinary cement