Effect of pH values on extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

生物浸出黄铜矿中pH值对嗜酸氧化亚铁硫杆菌分泌胞外蛋白和胞外多糖的影响（英文）

The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.

比较研究生物浸出黄铜矿中pH值对嗜酸氧化亚铁硫杆菌分泌胞外蛋白和胞外多糖的影响。实验结果表明:当pH值为1.0、1.5、2.0和2.5时,在细菌生长的适应期、对数生长期和稳定期,矿物表面吸附菌分泌的胞外蛋白量比胞外多糖量多,相反,浸出溶液中的悬浮细菌分泌的胞外蛋白量比胞外多糖量少;悬浮细菌主要通过分泌胞外多糖而不是胞外蛋白来抵抗如高金属离子浓度和不适宜pH等不利生长溶液环境;吸附细菌分泌的胞外多糖和胞外蛋白量主要正相关于溶液酸度而不是可溶性金属离子总浓度。这表明细菌主要是通过分泌更多胞外多糖来对抗不利环境,而胞外蛋白可能在生物浸出系统的氧化-还原反应中起重要作用。