Studies Of Magnetic Nanoparticles Features And Enzymes Activities In Burkholderia

Bacterial strain which can compound magnetic nanoparticles is isolated from Dongchang Lake, in Liaocheng City, Shangdong Province. Diameter of bacterial colony is 2-4 mm, milk white color, bright, opaque, sticky; Thallus is in the shape of rod with flagella, in size of 0.5×(1.5～3) μm.16S rDNA molecule identify it as Burkholderia, named as CG-1.Cultivate bacteria for 5 d, diameter of about 69 nm magnetic nanoparticles can be obtained. Analysis of magnetic nanoparticles by high resolution transmission electron microscopy (HRTEM), energy dispersion spectrum analysis (EDS), X ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results indicate that the inner atoms arrangement rules, the composition is made up of Fe3(PO4)2·8H2O, with low remanence (Mr) and high coercivity (Hc). Fourier transformation infrared spectroscopy analysis (FTIR) prove its surface with organic functional groups and chemical bond.Optimal condition for thallus grow is to take 10 mmol/L ferric citrate as iron source, media amount 25%, pH 6.5,28℃ and under dark treatment; Optimal condition to compound magnetic nanoparticles is to take 10 mmol/L ferric citrate as iron source, media amount 50%, pH 6.5,28 ℃ and under light treatment.Culturing 36 h it starts to compound. To take ferric citrate as iron source for 4 d, the content of H2O2 was decreased and the ability of producing hydroxyl radical was enhanced.The magnetic nanoparticles are obtained by two different methods of drying and freeze-drying, under the conditions of H2O2, can catalyze and oxidize peroxidase substrate TMB to blue color, showing that it has peroxidase activity. Under the condition of 40℃, pH 2.8, the catalytic activity is the highest. The H2O2 can be decomposed to produce O2, which is proved to have the activity of catalase. Using TMB as the substrate, reaction accord with Michaelis catalytic kinetics, Km=0.049 mmol/L.In the condition of H2O2, magnetic nanoparticles can catalyze dye isatin to decolorization. Decolorization percentage is 91.04% in the condition of pH 3.0, to postpone add H2O2 can accelerate the speed of decolorization, it has the ability to reuse.