| Microbe-mineral interaction has aroused sweeping concerns in the fileds of biohydrometallurgy and geochemistry. The adsorption between microbes and minerals is important step during this interaction. The microbial selective adsorption to different minerals has got a lot of attention from many researchers as well. This related research will help us to have a deeper understanding of microbial adsorption and mineral oxidation mechanism, which also contribute us to provide theoretical basis for strengthening of bioleaching process and microbial flotation.The experimental results are as follows:In this paper, we design and simulate a new selective adsorption bioreactor by using CAD software, which can identify the adsorption selectivity between bacteria and different minerals. This bioreactor consists of three parts:principal reactor, thermostatic controller and agitator. These above three parts were designed and simulated before we manufactured this bioreactor on the premise of cost. Consequently, we supply a novel tool for studying interaction between microbes and minerals and mechanism of mineral oxidation as well.In order to improve protein determination using ninhydrin, alkaline hydrolyzed proteins in high temperature and ninhydrin reagent prepared in the ethylene glycol dissolving system were first combined with respective advantage. Based on this modified method, we established a novel simple and sensitive assay to quantify the attached biomass on minerals duo to high sensitivity in the reaction between ninhydrin and amino acids. This assay demonstrates more accturate and sensitive than widely used Bradford assay and microscope counting method. In the range of0.35-1.75×107of bacterial concentration, the calibration curve is y=0.4x+0.02(R2=0.996), which has limite of detection of3.4×105cells. Pure BSA or bacteria with and without minerals were determined to demonstrate this assay can be used for direct quantification of attached biomass. As such, this simple and sensitive assay shows more advantages than Bradford assay and microscope counting method in quantification of attached biomass.Results of short-term adsorption between different bacteria and minerals show that electrostatic interaction and hydrophobic effect were not the main factor in the process of adsorption. The adsorption diversity was disappeared when the pulp and bacteria concentration was higher than0.03g/mL and8.6×108cells/mL, respectively. The change of pH value, ionic strength and temperature, which weakens the activity of bacteria, leads to decrease or even erase the diversity of adsorption. The masking agent (L-cysteine) and remover (Proteinase K) of active site could inhibit the adsorption and the diversity of adsorption. The adsorption was totally inhibited when bacteria were exposured to accessible enengy source. The above obtained results shows that the diversity of adsorption was controlled by chemotaxis of bacteria.Results from short-term selective adsorption shows that bacteria was induced across membrane by chemotaxis to attach to pyrite surface. Results obtained in long-term selective adsorption demonstrate the number of bacteria and attached bacteria was controlled by chemotaxis, which turned out to regulate the amount of metal ions bioleached. The above obtained results reveals that this designed selective adsorption bioreactor could be used to assay the selective bioleaching of bacteria to different minerals through short-term selective adsorption. |
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