Quantification of Rate Enhancement Factors of Kaolinite Dissolution by Reaction with Microbes

通过荧光假单胞菌（Pseudomonasfluorescens）对高岭石的溶解实验，研究了细菌对高岭石溶解速率的影响，并探讨了细菌对高岭石溶解的作用机理。还使用含有卵清蛋白（OVA）的蛋白质系统进行了类似的溶解实验，以确认蛋白质对高岭土溶解速率的影响。使用含有0.2 g高岭石和100 ml 10 mM NaCl溶液（含10^5至10^9个细胞/ml细菌）的分批反应器在25℃下进行细菌系统中的溶出实验，时间长达30天。也使用类似的方法进行蛋白质系统的溶解实验，然而，使用0.05、0.1、0.2、0.5和1.0 mg/ml的OVA代替细菌。结果表明，随着细菌浓度的增加，高岭石的溶解速率依次增加1.6、2.6、3.4、4.6和10.4倍 关于我们 和10^9个细胞/ml。溶解的铝离子的浓度也增加了50倍相比，铝氢氧化物，如三水铝石的平衡浓度与细菌浓度的增加。细菌系统溶液中有机分子的化学分析表明，细菌细胞释放出大量的蛋白质沿着少量的多糖和有机酸。因此，可以得出结论，这些主要由蛋白质组成的细胞外有机分子通过与高岭石表面相互作用而有助于提高高岭石溶解速率。它们还通过与溶解的Al离子进行络合而导致溶解的Al浓度增加。在含有OVA的蛋白质系统中的溶出实验显示，随着OVA浓度的增加，高岭石溶出增加了1.5倍、2.3倍、3.1倍、14.2倍和16.2倍。这一结果有力地表明，高岭石在细菌系统中的溶解可能是通过其与细菌细胞释放的胞外蛋白质的相互作用，通过配体促进溶解的机制而增强的。少

Dissolution experiments of kaolinite in bacterial systems containing bacteria (Pseudomonas fluorescens)were carried out to evaluate the effects of bacteria on dissolution rates and to elucidate the reaction mechanisms. Similar dissolution experiments using proteinic systems containing ovalbumin (OVA) were also performed to confirm the effects of protein on the kaolinite dissolution rates. The dissolution experiments in bacterial systems were performed using batch reactors containing 0.2 g of kaolinite and 100 ml of 10 mM NaCl solution with 10^5 to 10^9 cells/ml of bacteria at 25℃ for up to 30 days. The dissolution experiments of proteinic systems were also conducted using similar methods, however, 0.05, 0.1, 0.2, 0.5, and 1.0 mg/ml of OVA were used instead of bacteria. The results for the bacterial systems indicated that the dissolution rate of kaolinite increased by 1.6-, 2.6-, 3.4-, 4.6-, and 10.4-fold progressively with increasing bacterial concentrations of 10^5, 10^6, 10^7, 10^8 a … More nd 10^9 cells/ml, respectively, relative to the bacteria-free control. The concentrations of dissolved Al ions also increased up to 50 times compared to the equilibrium concentrations of Al-hydroxides such as gibbsite with increasing bacterial concentrations. The chemical analyses of organic molecules in the solutions of bacterial systems revealed that significant amounts of proteins were released from bacterial cells along with lesser amounts of polysaccharides and organic acids. Thus, it can be concluded that these extracellular organic molecules consisting mainly of proteins contribute to the enhancement of the rate of kaolinite dissolution by interacting with the kaolinite surfaces. They also lead to an increase in the dissolved Al concentrations by undergoing complexation with the dissolved Al ions. The dissolution experiments in the proteinic systems containing OVA exhibited greater enhancement in kaolinite dissolution of 1.5-, 2.3-, 3.1-, 14.2-, and 16.2-fold with increasing OVA concentrations. This result strongly suggests that the dissolution of kaolinite in bacterial systems may be enhanced by its interaction with the extracellular proteins released from the bacterial cells by the mechanism of ligand-promoted dissolution. Less