Screening And Breeding Of Silicate Bacteria For Bauxite And Silicon Releasing Study

One silicate strain 2# was isolated from corn soil of Shenyang suburb using nitrogen-free media, together with the reference strain of B. mucilaginosus 1#, and the morphology, physiological, biochemical characteristics, optimum culture conditions and the metallurgical ability of bacteria on slilicate ore were tested.The two strains both are rod shaped, with thick capsule in the cell surroundings. Several bacterial bodies can be linked together by the capsule to form zoogloea. The spores are elliptic or round in shape, non-flagella and Gram-staining negative. On the Aleksandrov plates, they formed smooth, round, convex, slimy, elastic, translucent and colourless colonies.The physiological and biochemical experiment were researched. The results indicated that there was very diverse about the biochemical aspects between the two strains, such as citrate utilization, utilization of different carbon sources and nitrogen sources, NaCl tolerance and pH tolerance etc. In other characteristics, such as hydrolyzation of glutin, phenylalaninase, nitrate reduction, hydrolyzation of casein they showed high degree of uniformity.The results of cultivating conditions showed that the strains entered the logarithmic growth phase after inoculating 36h, and the stable phase, after 72h.1# and 2# grow best within the pH range 8.0～8.5, the temperature is 28℃～30℃, the culture load is 100mL/250mL. The only difference was that the optimum nitrogen sources for 1# and 2# are NH4NO3 and (NH4)2SO4 respectively.After leaching 7 days by 1# and 2# strains, theAl2O3:SiO2 ratio of bauxite samples increased from 9.86 to 11.51 and 11.41 and about 40.17%and 43.27%of spores were produced respectively.The silicon releasing mechanisms also were studied. The tests showed that organic acids produced by bacteria were not the main reason for mineral solubilization and that the metabolizing products such as ex-polysaccharide worked as flocculant. The bacterial adsorption to mineral in the flask was studied in this experiment. The results showed that with the leaching time went by, the adsorptive bacteria got more and more. After leaching 8 days the percentage of adsorptive bacteria 1# and 2# can reach 61.70 and 59.09 respectively.