UREOLYTIC CALCIUM CARBONATE PRECIPITATION IN THE PRESENCE OF NON-UREOLYTIC COMPETING BACTERIA

摘要

Stimulation of ureolytic Microbially Induced CaCO3 Precipitation (MICP) innatural soils is likely to be affected by interactions between ureolytic and nonureolyticbacteria. In order to study these interactions we performed a MICPexperiment in artificial groundwater medium, inoculated with two model bacteria:Sporosarcina pasteurii and Bacillus subtilis, and supplemented with Nutrient Brothand 7 mM of urea. Control was inoculated with S. pasteurii. The experiment lasted10 days, during which ammonium, dissolved calcium, pH, dissolved inorganiccarbon (DIC) and optical density (OD) were measured.Results show that dissolved calcium was depleted at a higher rate in thepresence of non-ureolytic bacteria, despite lower pH and CO32- concentration. ODmeasurements show higher growth rate than in control samples. We suggest that thepresence of the non-ureolytic bacteria, B. subtilis, accelerates MICP process, throughthe addition of nucleation sites in the form of bacterial cells.