B ecause traditional methods of stabilizing soil by almost all chemical grouts are revealed to be toxic or at least to have hygienic side effects the need for new less pollutant, eco-friendly methods of soil stabilizing seem to be more important than ever before. Bacterial enhancement of soil mechanical characteristics such as shear strength, Uniaxial and triaxial compressive strength, Creep failure and many other tests testified the beneficial role of hydrolyzing bacteria in the new field emerged at the confluence of geotechnics, biotechnology, and geology. Microbially induced calcium carbonate precipitation has a lot of benefits over traditional sometimes toxic and destructive methods of stabilizing and strengthening of the soil. The use of this method has also astonishingly successfully been examined in the new field of cultural heritage and stone and rock conservation.in this study the role of two familiar bacteria Bacillus pasteurii and Bacillus subtilis as well as an uncommon bacteria in terms of microbially induced calcium carbonate precipitation ( bacillus licheniformis) were studied. the range of mechanical behaviour altering in the presence of all three bacteria were observed,this includes uniaxial compressive strength, hydraulic conductivity, pore reduction, surface treatment(tested by the Scotch Methode), Water vapour permeability, Capillary water absorption and some physiological tests including the famous Urease, Ammonium concentration measurement, Gram and Spore staining,were performed and proved that this method is indeed of importance even in the new field of stone and cultural heritage conservation by microbially induced calcium carbonate precipitation. to analyze the role of bacteria in micro scale SEM , EDX.SEMMAP and XRD analysis were used and ratified the influential behavior of Urea hydrolyzing bacteria in presence of calcium chloride and Urea.to further investigate the layer at which the precipitation occurred thin sections of the bacteria treated stone samples were stained by Alizarin red technic and to the surprise of the writer the depth of penetration of calcite layer was significant.
