环状芽孢杆菌对铝土矿浸出分解行为的影响

Effects of Bacillus circulans on decomposition behavior of bauxite

微生物对铝硅酸盐矿物的风化分解包含直接作用与间接作用两种方式。采用微孔滤膜将细菌与矿物隔离，在细菌一矿物直接接触与间接接触两种模式下，研究环状芽孢杆菌对铝土矿风化分解行为的影响。结果表明：在细菌生长的0～216h内，细菌及代谢产物能通过直接和间接作用共同促进铝土矿的分解，但直接作用的强度明显大于间接作用的；Al的溶出主要受直接作用的影响，而铝土矿中K、Fe和si的溶出率主要受φ接作用的影响；细菌代谢产物对溶出的A1具有明显的絮凝抑制作用，对Si具有良好的分散性能；细菌对铝土矿中不同晶体结构的硅酸盐矿物具有“选择性”的分解作用，具层状结构的高岭石、伊利石、绿泥石较架状结构的石英更易被细菌风化分解；在直接作用模式下，细菌在生长过程中会产生大量的胞外多聚物，细菌和矿粉之间会形成菌体一矿物聚集体，促进铝土矿的分解。分析认为，细菌对铝土矿的分解过程包括机械破坏、代谢产物溶蚀、络合作用及这3种作用的协同效应。

The microbial decomposition mechanisms of bauxite include direct and indirect mechanism, while the contribution of each mechanism to the mineral weathering is still in controversy. The impact of Bacillus circulans on decomposition of bauxite was studied under the conditions of microbe-mineral direct contact and indirect contact. The microfiltration membrane was used to segregate mineral powder from bacteria. The results show that Bacillus circulans and its metabolites can clearly promote the degradation of bauxite through either mechanisms during incubation in 0- 216 h, and the effect of direct mechanism on the mineral degradation is more efficient than that of indirect one. The A1 dissolution from bauxite is mainly determined by the direct mechanism, and K, Fe, Si are considered to be released by indirect mechanism. The bacterial metabolites can flocculate and inhibit AI in supernatants, but have good dispersibility on Si. The Bacillus circulans can selectively degrade different minerals due to the difference in mineral crystal structure. Kaolinite, illite and chlorite with layer structure are more easily decomposed than quartz with framework structure by bacteria. The Bacillus circulans can produce extracellular polymeric substances during incubation, and form the mycelium-mineral aggregate between bacteria and mineral powder. It is concluded that the Bacillus circulans can decompose bauxite at the mechanical breakage of the mycelium growth, the corrosion and complexation of metabolites and their synergetic operation.