Magnesium (Mg) is an essential macronutrient that can be obtained through mineralization of mine spoils. The leftover mine spoils of magnesite mines still contain a reliable amount of Mg in it. The Mg present in raw magnesite spoils is in its carbonate form and hence it has to be mineralized to convert it into plant available soluble forms of Mg. The effect of B. cereus and B. stercoris in the mineralization of Mg has been studied in synthetic mineral salts medium (MSM). To obtain maximum mineralization results it is important to know the optimal conditions of the organisms under which they can grow and produce more Mg. The mineralizing capability of the individual organisms and their combined effect as a consortium under various concentrations of carbon source, pH, temperature and soil organic matter has been studied. It has been seen that the organisms grow and mineralize better when 1% of glucose has been supplemented as carbon source. The optimal pH and temperature were found to be pH 7 and 35°C, respectively. The addition of anthraquinone-2-sulphonic acid (ADQS) as soil organic matter enhances the mineralization Mg in synthetic medium. Rendering to SEM and EDX analysis, the mineralization of Mg in the synthetic medium was established.