Optimized carbonate micro-particle production by Sporosarcina pasteurii using response surface methodology

Abstract

Calcium carbonate materials are frequently used in various industries and for diverse environmental engineering applications, such as water and wastewater treatment and reduction of soil acidity for agriculture. In this study, optimization of microbially induced calcium carbonate micro-particle production by Sporosarcina pasteurii ATCC 11859 was investigated with the response surface methodology (RSM). The natural calcium carbonate precipitation reaction is largely dependent on environmental factors and in the presence of microorganisms. Therefore, a central composite design (CCD) was employed to determine the different concentrations of urea, calcium chloride and nickel (II) nitrate to be investigated. The experimental CCD results were applied in a quadratic model to predict the optimum concentrations of these factors to maximize the production of calcium carbonate. The mathematical model determined that the optimum urea, calcium chloride and nickel (II) nitrate concentrations were 42.12g/l, 6.93g/l, and 0.071g/l, respectively. Under these conditions, S. pasteurii growth and the calcium carbonate precipitation rates were 0.786h−1 and 0.145h−1, respectively. Also, at these optimum conditions, the urease activity was 3.4U/ml, which was 2.5 times higher than the current calcium carbonate conditions described in the literature. The size of the calcium carbonate particles produced ranged from 0.1μm to 10μm in diameter.