Microbially Induced Calcite Precipitation (MICP) can be accomplished by the combined action of urea and calcium in the presence of urease-producing bacteria such as Sporosarcina pasteurii. When applied to soil, it can prevent soil loss by generating calcium carbonate precipitation among soil particles. In this regard, the activity of urease plays a key role so that this study aims to increase the enzyme activity of S.pasteurii culture by controlling the urea concentration during cultivation. The urease activity of the culture was highest under 0.1 M urea concentration among five different urea conditions including 0, 0.01, 0.1, 0.33, 1 M. The urease activities were 11.2 ± 0.6, 7.8 ± 0.6, 4.4 ± 0.2, and 0.9 ± 0.1 mM urea hydrolyzed/min under the conditions of 0.1, 0.33, 1, 0.01 M urea concentration, respectively. Such a decrease with increasing urea concentration can be attributed to the ammonia liberated during urea hydrolysis. The free ammonia were concentrated and seemed to inhibit the growth of S.pasteurii at 0.33 and 1 M urea concentrations. MICP was applied to a sandy soil with the S.pasteurii culture cultivated under 0.1 M urea condition. After three and five repeated application of the culture medium, the calcium carbonate precipitated were 16.9 and 55.9 mg/g-soil, respectively. Soil loss ratio, which was defined as the weight of soil lost to the weight of total soil, decreased with increasing the concentration of calcium carbonate precipitated showing 9 and 3% in 16.9 and 55.9 mg-CaCO3/g-soil, respectively.

Improvement of the urease activity of Sporosarcina pasteurii culture by controlling urea concentration and its application for preventing soil loss by microbially induced calcite precipitation

254th National Meeting (2017)

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