摘要
In this paper, culture experiments of carbonate precipitation using Lagoa Vermelha medium with 4∶1 molar Mg/Ca ratio were made under the mediation of Clostridium sp. (SN-1) from Qinghai Lake sediment. The results showed that 1) SN-1 helped promote the formation of Mg-bearing calcites with special shapes, but only irregular carbonate minerals were formed in the aseptic experiments; and 2) specifically shaped Mg-bearing calcite might nucleate and grow on the cell surfaces of bacteria, and then evolve from rod-like to dumbbell-like, cauliflower-like and spherulite shapes. The authors suggest that this is because more negative ionic groups concentrated on the polar ends than on the middle parts of rod-shaped bacteria, resulting in attracting more Ca 2+ and Mg 2+ on both polar ends of bacterial cells.