Farahat Mohsen, Hirajima Tsuyoshi, Sasaki Keiko, Doi Katsumi
Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395, Japan.
Colloids Surf B Biointerfaces. 2009 Nov 1;74(1):140-9. doi: 10.1016/j.colsurfb.2009.07.009. Epub 2009 Jul 21.
The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH <4.3 for quartz and at pH 4.5-8.5 for corundum. For hematite, cell adhesion remained low at all pH values. The microbe-mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe-mineral interaction energy (Hamaker constants and acid-base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 x 10(9)cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite-quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62.
对大肠杆菌在石英、赤铁矿和刚玉上的黏附进行了实验研究。使用了一种具有表达二氧化硅沉淀蛋白基因的大肠杆菌菌株。在pH值小于4.3时观察到石英的最大细胞黏附，而在pH值4.5 - 8.5时观察到刚玉的最大细胞黏附。对于赤铁矿，在所有pH值下细胞黏附都很低。采用扩展的DLVO理论方法评估微生物 - 矿物黏附。通过实验确定了计算微生物 - 矿物相互作用能的基本参数（哈梅克常数和酸碱成分）。扩展的DLVO方法可用于解释黏附实验结果。测定了大肠杆菌对三种氧化物矿物可浮性的影响，结果表明，在酸性pH值下，大肠杆菌可作为石英的选择性捕收剂，当细胞浓度为1.5×10⁹个/毫升时，90%的石英可上浮。然而，在类似条件下，只有9%的赤铁矿和30%的刚玉可上浮。通过使用大肠杆菌且不添加任何试剂，能够从赤铁矿 - 石英混合物中分离出石英，牛顿效率为0.70。通过大肠杆菌从刚玉混合物中去除石英，牛顿效率为0.62。
